Bulletin of the American Physical Society
2015 Fall Meeting of the APS Division of Nuclear Physics
Volume 60, Number 13
Wednesday–Saturday, October 28–31, 2015; Santa Fe, New Mexico
Session EA: CEU Poster Session |
Hide Abstracts |
Room: Exhibit Hall |
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EA.00001: Understanding GRETINA using angular correlation method Madeline Austin The ability to trace the path of gamma rays through germanium is not only necessary for taking full advantage of GRETINA but also a promising possibility for homeland security defense against nuclear threats. This research tested the current tracking algorithm using the angular correlation method by comparing results from raw and tracked data to the theoretical model for Co-60. It was found that the current tracking method is unsuccessful in reproducing angular correlation. Variations to the tracking algorithm were made in the FM value, tracking angle, number of angles of separation observed, and window of coincidence in attempt to improve correlation results. From these variations it was observed that having a larger FM improved results, reducing the number of observational angles worsened correlation, and that overall larger tracking angles improved with larger windows of coincidence and vice-verse. Future research would be to refine the angle of measurement for raw data and to explore the possibility of an energy dependence by testing other elements. [Preview Abstract] |
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EA.00002: Rotational Bands in 172W J. Greenberg, C.J. Guess, S. Tandel, P. Chowdhury, M.P. Carpenter, D.J. Hartley, R.V.F. Janssens, T.L. Khoo, T. Lauritsen, C.J. Lister, D. Seweryniak, U. Shirwadkar, X. Wang, S. Zhu Studying the structure of rotational bands in $^{172}$W is valuable for gaining a better understanding of deformed nuclei. Highly excited states of the isotope were populated from a 230 MeV $^{50}$Ti beam incident on a $^{128}$Te target at Argonne National Laboratory using the ATLAS accelerator. $\gamma$ emissions from $^{172}$W in the range were measured using Compton suppressed germanium detectors in the Gammasphere array. Using this data, three new rotational bands were found, and several other bands were expanded. [Preview Abstract] |
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EA.00003: Canadian Penning Trap Mass Measurements using a Position Sensitive MCP Trenton Kuta, Ani Aprahamian, Scott Marley, Andrew Nystrom, Jason Clark, Adrian Perez Galvan, Tsviki Hirsh, Guy Savard, Rodney Orford, Graeme Morgan The primary focus of the Canadian Penning Trap (CPT) located at Argonne National Lab is to determine the masses of various isotopes produced in the spontaneous fission of Californium. Currently, the CPT is operating in conjunction with CARIBU at the ATLAS facility in an attempt to measure neutron-rich nuclei produced by a 1.5Curie source of Californium 252. The masses of nuclei produced in fission is accomplished by measuring the cyclotron frequency of the isotopes circling within the trap. This frequency is determined by a position sensitive MCP, which records the relative position of the isotope in the trap at different times. Using these position changes over time in connection with a center spot, angles between these positions are calculated and used to determine the frequency. Most of the work currently being conducted on the CPT is focused on the precision of these frequency measurements. The use of traps has revolutionized the measurements of nuclear masses to very high precision. The optimization methods employed here include focusing the beam in order to reduce the spread on the position of the isotope as well as the tuning of the MR-ToF, a mass separator that is intended on removing contaminants in the beam. [Preview Abstract] |
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EA.00004: sPHENIX Hadronic Calorimeter Scintillator Studies Reuben Byrd A new form of matter called the Quark-Gluon Plasma (QGP) was discovered with the Relativistic Heavy Ion Collider (RHIC). PHENIX is an experiment at RHIC that helped with this discovery, but plans are being made to replace it with a new spectrometer with different capabilities. The sPHENIX detector will consist of a superconducting solenoid magnet, hadronic and electromagnetic calorimetry and charged particle tracking. sPHENIX will enable a rich jet physics program that will address fundamental questions about of the nature of the QGP. The new detector will provide full azimuthal coverage and $\pm$ 1.1 in pseudorapidity. The Hadronic Calorimeter is a major subsystem in this detector. It is made of alternating layers of scintillating tiles and steel plates. In the current prototype the tiles are covered with a reflective coating and contain wavelength shifting fibers. As the second round of prototypes are developed for an upcoming beam test, special care is being taken to provide uniform light collection efficiency across the detector. Studies are being conducted to ensure this by careful alignment of the silicon photomultipliers to the fibers and varying coatings on the tiles. The effects of the coating will be presented along with the current status and ongoing plans. [Preview Abstract] |
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EA.00005: Charge-asymmetry dependence of kaon elliptic flow in Au$+$Au collisions at $\sqrt{s_{\mathrm{NN}}} = $ 27 GeV from STAR Keenan Cabrera Theory predicts that a chiral magnetic wave (CMW) at finite baryon density can induce a charge-asymmetry dependence of elliptic flow (v$_{\mathrm{2}})$ of particles produced in heavy-ion collisions [1]. In the case of pions, STAR has observed that v$_{\mathrm{2}}(\pi ^{\mathrm{-}})$-v$_{\mathrm{2}}(\pi^{\mathrm{+}})$ exhibits a linear dependence on charge asymmetry with a positive slope in Au$+$Au collisions from 27 to 200 GeV [2]. This is consistent with the CMW picture. At lower collision energies, it was found that the charge-asymmetry integrated v$_{\mathrm{2}}$ for negative pions is higher while for kaons, the positive charge is favored. Therefore, an observation of the same positive linear dependence of kaon v$_{\mathrm{2}}$ difference on charge asymmetry will provide a further test on the CMW predictions in heavy-ion collisions. In this work, we will present the status of our kaon elliptic flow measurements as a function of charge asymmetry for Au$+$Au collisions at $\sqrt{s_{\mathrm{NN}}} = $ 27 GeV. \\[4pt] [1] Y. Burnier, D. Kharzeev, J. Liao, and H. Yee, Phys.Rev.Lett. 107 (2011) 052303.\\[0pt] [2] L. Adamczyk et al [STAR Collaboration], Phys.Rev.Lett. 114 (2015) 252302.\\[0pt] [3] L. Adamczyk et al [STAR Collaboration], Phys.Rev.Lett. 110 (2013) 142301. [Preview Abstract] |
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EA.00006: High Resolution Gamma Ray Analysis of Medical Isotopes Thomas Chillery Compton-suppressed high-purity Germanium detectors at the University of Massachusetts Lowell have been used to study medical radioisotopes produced at Brookhaven Linac Isotope Producer (BLIP), in particular isotopes such as Pt-191 used for cancer therapy in patients. The ability to precisely analyze the concentrations of such radio-isotopes is essential for both production facilities such as Brookhaven and consumer hospitals across the U.S. Without accurate knowledge of the quantities and strengths of these isotopes, it is possible for doctors to administer incorrect dosages to patients, thus leading to undesired results. Samples have been produced at Brookhaven and shipped to UML, and the advanced electronics and data acquisition capabilities at UML have been used to extract peak areas in the gamma decay spectra. Levels of Pt isotopes in diluted samples have been quantified, and reaction cross-sections deduced from the irradiation parameters. These provide both cross checks with published work, as well as a rigorous quantitative framework with high quality state-of-the-art detection apparatus in use in the experimental nuclear physics community. [Preview Abstract] |
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EA.00007: $\pi^0$ Reconstruction using the Muon Piston Calorimeter Extension Dhruv Dixit The Muon-Piston Calorimeter Extension (MPC-EX) is a new detector in the PHENIX experiment at the Relativistic Heavy Ion Collider that was installed for the recent Run 15 of the experiment. In polarized p+p and polarized p+A collisions, an important measurement is the yield and momentum distribution of direct photons. Unaffected by the strong force, direct photons traverse the dense medium in the collision zone mostly unchanged, thereby providing information about the initial stages of the collision. However, there is a huge background of photons from other sources, primarily $\pi^0$ which decay into two photons. The opening angle between the decay photons becomes smaller with higher energies of the original $\pi^0$. For energies greater than $\sim$20 GeV, the Muon Piston Calorimeter (MPC) cannot distinguish the two decay photons from a single photon, as their showers merge. The MPC-EX, an 8-layer tungsten and silicon sensor sandwich in front of the MPC, can measure and image the shower development, and help distinguish between direct photons and $\pi^0$ decay photons up to higher energies than the MPC alone. We will describe the MPC-EX detector and its readout, and present the calibration procedures applied to the data in order to obtain the $\pi^0$ spectrum. [Preview Abstract] |
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EA.00008: Single particle structure of $^{209,210}$Pb and $^{206}$Hg investigated through the deep inelastic reaction $^{136}$Xe $+ \quad^{208}$Pb C.R. Hamill, E.A. MCCUTCHAN, A.A. SONZOGNI, J.S. BARRETT, W. LOVELAND, R. YANEZ, S. ZHU, A.D. AYANGEAKAA, M.P. CARPENTER, J.P. GREENE, R.V.F. JANSSENS, T. LAURITSEN, C.J. CHIARA, J.L. HARKER, W.B. WALTERS, A.B. Brown The region of nuclei around $^{208}$Pb is rich in information relevant to nuclear structure and astrophysics, yet is relatively unexplored. To access these nuclei, a deep inelastic reaction was performed at Argonne National Laboratory's Gammasphere, where a $^{136}$Xe beam was incident on a $^{208}$Pb target. Our analysis focused on$^{\, 209}$Pb, $^{210}$Pb and $^{206}$Hg, and our findings of new relevant information include energy level schemes, angular correlations resulting in level spins and gamma-ray multipolarities, and half-lives of isomeric states. Known transitions in these nuclei were observed and confirmed and coincidence techniques were used to expand upon this data to discover new excited states. The results from this study were compared to theoretical shell model calculations and states interpreted in terms of valence nucleon excitation or coupling of the extra neutron(s) or proton holes to the double magic (Z$=$82, N$=$126) $^{208}$Pb core. Results will be presented. [Preview Abstract] |
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EA.00009: Testing of multigap Resistive Plate Chambers for Electron Ion Collider Detector Development Hannah Hamilton Despite decades of research on the subject, some details of the spin structure of the nucleon continues to be unknown. To improve our knowledge of the nucleon spin structure, the construction of a new collider is needed. This is one of the primary goals of the proposed Electron Ion Collider (EIC). Planned EIC spectrometers will require good particle identification. This can be provided by time of flight (TOF) detectors with excellent timing resolutions of 10 ps. A potential TOF detector that could meet this requirement is a glass multigap resistive plate chamber (mRPC). These mRPCs can provide excellent timing resolution at a low cost. The current glass mRPC prototypes have a total of twenty 0.1 mm thick gas gaps. In order to test the feasibility of this design, a cosmic test stand was assembled. This stand used the coincidence of scintillators as a trigger, and contains fast electronics. The construction, the method of testing, and the test results of the mRPCs will be presented. [Preview Abstract] |
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EA.00010: Study of Omega-proton correlations in heavy-ion collisions Yifei Han Recently the STAR experiment at RHIC measured Lambda-Lambda correlations from Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV [1] to search for the H particle (uuddss). The correlation strength indicated that the Lambda-Lambda interaction is weak and is unlikely to be attractive enough to form a bound state. A recent lattice QCD calculation [2] predicted a possible di-baryon bound state with Omega-nucleon. Thus, we will extend the correlation measurements to Omega-proton, which could potentially be a sensitive approach to search for such a state. We will present the Omega-proton correlations based on data collected by STAR in Au+Au collisions at $\sqrt{s_{NN}}$ =200 GeV, and discuss the physics implications. [1] L. Adamczyk et al [STAR Collaboration], Phys. Rev. Lett.114(2015)022301 [2] F. Etminan et al [HAL QCD Collaboration], arXiv:1403.7284 [Preview Abstract] |
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EA.00011: Calibrating the PHENIX Muon Piston Calorimeter for Au+Au collisions at $\sqrt{S_{NN}}$=200, 62.4, 39, and 7.7 GeV Carlos Herrera Acevedo The PHENIX Muon Piston Calorimeter (MPC), a homogenous electromagnetic calorimeter, covers forward/backward pseudorapidities ($3.1<|\eta|<3.9$). MPC calibrations of data collected by PHENIX during the 2010 RHIC run are underway. These will be used for the measurement of transverse energy in the forward/backward direction. For the calibration, an iterative process is used in which photon clusters are paired to produce tower by tower mass plots containing neutral pion peaks. The gains of each tower are adjusted until the peaks in the mass histograms are shifted to the positions predicted by a full detector simulation. For towers in which a neutral pion peak is not immediately evident, other methods can be applied to adjust the gains until a neutral pion peak appears. [Preview Abstract] |
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EA.00012: Rapidity Dependent Pion Spectra from Fixed-Target $\sqrt{s_{NN}}$ = 4.5 Au+Al and Al+Au Collisions at STAR Jessica Howard An internal gold target was installed in the STAR detector in the winter of 2014. Special test runs were taken in 2015 with injection energy beams of both gold and aluminium ions. Utilizing these fixed-target data, STAR can extend the reach of the beam energy scan to lower center-of-mass energies and higher baryon chemical potentials than previously achieved. This allows for a more thorough search for the possible onset of deconfinement and the phase transition between hadronic and partonic matter. One signature associated with the onset of deconfinement relates the width of the pion rapidity distributions to those predicted by a hydrodynamic model [1]. In this poster we will present rapidity dependent fixed-target pion spectra from Au+Al and Al+Au datasets at center-of-mass energies of 4.5 GeV. Studying both kinematics will allow coverage of the full rapidity distribution, which is expected to be shifted in the gold going direction [2]. \\[4pt] [1] M. Bleicher hep-ph/0509314, H. Petersen nucl-th/0611001, A. Rustamov arXiv:1201:4520\\[0pt] [2] G.S.F. Stephans et al. [E802], Nucl. Phys. A566 (1994)269c. [Preview Abstract] |
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EA.00013: Handling Difficult Towers in the Calibration of the PHENIX Muon Piston Calorimeter (MPC) for Analysis of RHIC Au+Au Collisions Emran Lallow The PHENIX Muon Piston Calorimeter (MPC) is an electromagnetic detector with a kinematic coverage of ($3.1<|\eta|<3.9$). This allows for measurements at high forward and backward pseudorapidity and will be used to measure transverse energy in $\sqrt{S_{NN}}$=200, 62.4, 39, and 7.7 GeV RHIC Au+Au collisions in this kinematic region. The towers will be calibrated by using an iterative procedure in which neutral pions are reconstructed from their decay photons. To augment the iterative process, rough calibrations of individual towers can be obtained by direct examination of ADC distributions. These rough calibrations serve as input to the more rigorous neutral pion reconstruction method and will be described in this poster. [Preview Abstract] |
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EA.00014: Sensor and Instrumentation Development for Cryogenic Detectors Nicholas Allen, Micheal Febbraro, Steven Pain, Christine Aidala, Ezra Lesser, Aaron White In the study of nuclear science, there is an ever increasing need for better efficiency and resolution in In nuclear sciences, new detectors with improved detection efficiency and energy resolution are constantly needed to drive experimental discovery and accuracy. Certain cryogenic liquids, particularly liquid noble gases such as Argon and Xenon, are very sensitive to energy deposited by ionizing particles and have many other useful properties for detector development. Developing these cryogenic liquids to operate with known detection methods offers exciting opportunities for experimental setups and has a wide variety of uses with regards to nuclear studies, such as gamma ray, neutron, and neutrino detection. However, operating at such low temperatures presents many complications when trying to effectively control and maintain detectors. In this poster, I will present some of the equipment and systems developed for particular low temperature applications. This will include the use of platinum resistance thermometers, capacitance-based liquid level sensors, and various systems used to regulate fluid flow for cryogenic detector systems. [Preview Abstract] |
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EA.00015: High-precision gamma-ray spectroscopy of 82Rb and 72As, two important medical isotopes used in positron emission tomography Michael Nino, E. McCutchan, S. Smith, A. Sonzogni, L. Muench, J. Greene, M. Carpenter, S. Zhu, C. Lister Both 82Rb and 72As are very important medical isotopes used in imaging procedures, yet their full decay schemes were last studied decades ago using low-sensitivity detection systems; high quality decay data is necessary to determine the total dose received by the patient, the background in imaging technologies, and shielding requirements in production facilities. To improve the decay data of these two isotopes, sources were produced at the Brookhaven Linac Isotope Producer (BLIP) and then the Gammasphere array, consisting of 89 Compton-suppressed HPGe detectors, at Argonne National Laboratory was used to analyze the gamma-ray emissions from the daughter nuclei 82Kr and 72Ge. Gamma-ray singles and coincidence information were recorded and analyzed using Radware Gf3m software. Significant revisions were made to the level schemes including the observation of many new transitions and levels as well as a reduction in uncertainty on measured $\gamma $-ray intensities and deduced $\beta $-feedings. The new decay schemes as well as their impact on dose calculations will be presented. [Preview Abstract] |
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EA.00016: Particle Identification in the MPC-EX Detector at the PHENIX Experiment Robert Read, Vincent Andrieux, Christine Aidala One of the newest additions to the PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC) is a Si-W electromagnetic preshower detector, the MPC-EX, which extends the capabilities of the existing forward region electromagnetic calorimeter (MPC). The addition of the MPC-EX allows for reconstruction of neutral pions at higher energy and transverse momentum than previously possible with only the MPC. The new detector enables resolution of single photons from neutral pion decay for pion momenta up to 80~GeV/c; the previous limit was approximately 15~GeV/c. A primary motivation for the MPC-EX was to continue investigations into various transverse single-spin asymmetries seen at RHIC, including for neutral pion and eta meson production. The MPC-EX was installed in late 2014 and took its first data during PHENIX Run-15, with $\sqrt{s_{NN}}=200$~GeV p+p, p+Au, and p+Al collisions with the proton beam transversely polarized. To capitalize on the new capabilities of PHENIX with the MPC-EX, it is essential to identify the different particles in the detector. The status of particle identification using this detector will be presented with emphasis on identifying minimum ionizing particles and key neutral hadrons through their associated electromagnetic decay products in the MPC-EX. [Preview Abstract] |
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EA.00017: Corrections to Transverse Energy Measurements taken by the PHENIX Muon Piston Calorimeter David Reinert The PHENIX Muon Piston Calorimeter (MPC) is being used to measure transverse energy produced in the forward/backward kinematic region ($3.1<|\eta|<3.9$) by the collision of Au+Au nuclei at the Relativistic Heavy Ion Collider (RHIC). Undergraduates at Muhlenberg College have worked since 2013 to produce and verify corrections for these measurements. To this point, corrections for the inflow and outflow of energy (mostly due to particle decays), efficiency, and hadronic response have been considered and will be described. Attempts to consistency check these current attempts using other approaches will also be described. Efforts are currently underway to analyze 2010 Au+Au collisions at $\sqrt{S_{NN}}$=200, 62.4, 39, and 7.7 GeV. [Preview Abstract] |
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EA.00018: Development of mRPCs Using 3D Printed Resistive Plate Stacks Jun Hui See Toh ePHENIX will be an experiment at the future Electron-Ion Collider (EIC) to study nucleon spin structure and nuclear effects in nucleon structure. The spin dependent quark-flavor structure of the proton will be studied through semi-inclusive deep inelastic scattering with identified hadrons. These measurements will require superior particle identification capabilities. The EIC group at UIUC aims to develop multi-gap resistive plate chambers (mRPCs) with 10 ps timing resolution for a Time-of-Flight (TOF) detector at EIC. To create a cost efficient detector, mRPCs using 3D printed resistive plate stacks have been constructed and are being evaluated. An mRPC prototype consisting of two stacks of 5 layers of 300 $\mu $m gas gaps had been printed using stereolithographic technique. The printed stacks were then sandwiched between printed circuit board plates, which contain pickup electrodes for signal readout and will be connected to high voltage. The presentation will discuss details of the construction of the 3D printed mRPC prototype and will provide first results on efficiency and timing resolution. [Preview Abstract] |
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EA.00019: Particle Identification Using Cost Effective mRPC Technology for Time-of-Flight Measurements with Less than 10 ps Time Resolution Taylor Shimek This presentation will introduce the use of multi-gap Resistive Plate Chambers (mRPCs) for time of flight (TOF) based particle identification (PID) in nuclear and high-energy physics. The mRPC technology is developed for use in future experiments at the planned Electron Ion Collider, EIC. TOF PID using mRPCs with 10 ps timing resolution will make it possible to precisely determine the flavor content of valence- and sea-quarks in the proton through semi-inclusive deep inelastic scattering with identified pions and kaons. A first mRPC prototype using float glass resistive plates at UIUC has reached a timing resolution of 21 ps. In this presentation I discuss an effort to replace the float glass with cheaper Mylar-based resistive plates. I will also discuss the design and construction of a first prototype and present initial results on signal development, efficiencies and timing resolution of the mRPC prototype. [Preview Abstract] |
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EA.00020: Cosmic Test Stand Development for Electron Ion Collider Detector R\&D Cecily Towell Since the beginning of the spin crisis, questions concerning how the partons inside a nucleon contribute to the nucleon's overall spin have remained unanswered. A new accelerator, called the Electron Ion Collider (EIC), is being designed to answer this and other fundamental questions. The EIC uses an electron beam accelerated to relativistic speeds, which can be collided with polarized protons. This will provide a unique look into the spin structure of the nucleon. However, EIC requirements necessitate significant upgrades in detector performance. This includes Time of Flight (TOF) detectors, which need better timing resolution to improve their particle identification capabilities. New designs for multi-gap Resistive Plate Chambers have the potential of improving the TOF timing resolution to 10 ps. To test this prototype design, a cosmic ray test stand has been assembled which utilizes the coincidence of two hodoscopes as a trigger. To verify the accuracy of the trigger, thereby ensuring the validity of the test stand results, timing and trigger studies were conducted. The results of these systematic studies were compared to expected values produced by a cosmic flux simulation. These studies and their findings will be presented. [Preview Abstract] |
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EA.00021: Study of proton-kaon correlations in heavy-ion collisions Runze Zhao The proton-kaon (p-K$^{+}$, p-K$^{-}$, antiproton-K$^{+}$ and antiproton-K$^{-})$ correlations can be sensitive to several physics topics in heavy-ion collisions. The same-charge p-K correlation could be sensitive to a possible formation of penta-quark candidates with quark contents (uudu-sbar). The opposite-charge p-K correlation measurement could be sensitive to the formation of Lambda(1520) and Lambda(1405). In particular, the Lambda(1405) was suggested by recent Lattice QCD calculations [1] as a molecular proton-kaon state. The mass of Lambda(1405) is below the p-K threshold, and its possible coalescence formation from p-K could deplete the p-K correlation at small two-particle relative momenta. We will present the status and further physics implications of p-K correlations from Au$+$Au collisions at $\sqrt{s_{\mathrm{NN}}} = $ 200 GeV at the STAR experiment. \\[4pt] [1] J.M.M. Hall et al, Phys Rev Lett. 114(2015)132002 [Preview Abstract] |
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EA.00022: Third-Scale Prototype of a Shielded Magnet for Measurement of the Electric Dipole Moment of the Neutron Aritra Biswas Discovery of an electric dipole moment in neutrons (nEDM) would be a novel instance of CP violation, with implications for extending the Standard Model and potentially helping explain matter-antimatter asymmetry. Experiments using shifts in polarized neutron spin-precession frequency to measure the nEDM are prone to a geometric phase (GP) effect, caused by gradients of the magnetic field, that can create a false signal. Preventing the GP effect requires precise engineering to create a space-uniform magnetic field. We present a third-scale prototype of a shielded magnet suitable for a more precise nEDM measurement, with improvements over earlier models. The field is produced by a $\cos\theta$ coil wound with superconducting (SC) wire. Two cylindrical shields made of ferromagnetic Metglas and SC lead surround the magnet; the lead shield is closed on top and bottom with SC lead endcaps. An aluminum shell surrounds these components and serves as a vacuum chamber, cooling its interior to 4 K such that the coil wire and lead shield become SC. A cavity in this shell serves as a warm bore, allowing a magnetic probe to explore the field around fiducial volumes which will be used to measure the nEDM in the full-scale experiment. The magnetic field profile of this prototype is presented. [Preview Abstract] |
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EA.00023: Efficacy of Cosmic Ray Shields Nicholas Rhodes This research involved testing various types of shielding with a self-constructed Berkeley style cosmic ray detector, in order to evaluate the materials of each type of shielding's effectiveness at blocking cosmic rays and the cost- and size-efficiency of the shields as well. The detector was constructed, then tested for functionality and reliability. Following confirmation, the detector was then used at three different locations to observe it altitude or atmospheric conditions had any effect on the effectiveness of certain shields. Multiple types of shielding were tested with the detector, including combinations of several shields, primarily aluminum, high-iron steel, polyethylene plastic, water, lead, and a lead-alternative radiation shield utilized in radiology. These tests regarding both the base effectiveness and the overall efficiency of shields is designed to support future space exploratory missions where the risk of exposure to possibly lethal amounts of cosmic rays for crew and the damage caused to unshielded electronics are of serious concern. [Preview Abstract] |
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EA.00024: Using an ARM Processor to boost data acquisition rates Anthony Brown It has been proposed, Fermilab E-1067, to use the SeaQuest (E906/E1039/1037) dimuon spectrometer to do a search for the dark photon and dark Higgs. The concept is that it would run in a parasitic mode with only minor upgrades to the spectrometer. There are various requirements for the upgrades but one of them is to increase the DAQ rates and one minimal cost approach to do this will be discussed. The currently running SeaQuest (E906) experiment has modest rate requirements of around 1 kHz. Since the dark particle search would involve recording particles originating in the first magnet used as a beam dump, the data rate will be higher than recording events just from the target. Thus the DAQ rate capability will need to be increased to around 10 kHz. There exists a possible very low cost solution as the Academica Sinica designed TDCs contains an ARM processor that was not needed to meet the original SeaQuest (E906 needs). Since the 120 GeV beam from the Main Injector is delivered in a 4 second spill, once per minute and the ARM processor on the TDC has two dual-ported memory chips, these could be used to store data during each spill and then read the data out in the time between spills. [Preview Abstract] |
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EA.00025: Using Neural Networks to Detect Di-muon Tracks for Fermilab E906/SeaQuest Paul Carstens The experiment E906/SeaQuest aims to gain further insight into the nucleon quark sea by gathering information about the anti-down/anti-up ratio produced by Drell-Yan events. SeaQuest collides a 120 GeV proton beam with one of several targets, liquid hydrogen, liquid deuterium, carbon, tungsten, iron, and two calibration targets, empty target and no target. The di-muon pairs created by the Drell-Yan events are monitored by four detector stations. Each has a set of hodoscopes, stations one, two, and three have wire chambers, and station four, which has a lower resolution, has a set of prop tubes. In order to separate the useful Drell-Yan events from dump events and background noise we employ the use of the hodoscopes to trigger potentially useful events to keep. This neural network would learn to properly discern Drell-Yan events by associating hodoscope readings from real data with results from existing trigger systems. By doing this, we could efficiently replicate existing results while alleviating the processing needed. [Preview Abstract] |
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EA.00026: Improving Kinematic Resolution in SeaQuest Event Reconstruction Program Isaac Mooney, J.G. Rubin, C.A. Aidala Fermi National Accelerator Laboratory (FNAL) Experiment-906/SeaQuest uses the Drell-Yan process - specifically dimuon production through quark-antiquark annihilation - to give insight into nucleon structure. The process is induced with a 120 GeV beam of protons from the Main Injector, incident on liquid or solid targets. High-energy muons scatter through a large solid iron focusing magnet (FMAG) and are bent by the magnetic field. They then pass through an air-core analysis magnet (KMAG), and are detected by hodoscopes, proportional chambers and proportional tubes. Track reconstruction software is used to recreate process kinematics and estimate the scattering vertex. The influence of the magnets can be approximated as a bend at a single point along the track trajectory and the track reprocessed, forced to either the center of the target or the most likely origin in FMAG - depending on the estimated scattering vertex position - from that position. To find the best bend plane, the retracked virtual photon invariant mass and Feynman $x$ ($x_{\mathrm{F}}$) were compared to Monte Carlo, then each residual distribution's width as a function of momentum was minimized. We input the correction into the track reconstruction software for improved invariant mass and $x_{\mathrm{F}}$ resolution. [Preview Abstract] |
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EA.00027: jTracker and Monte Carlo Comparison Lauren Selensky SeaQuest is designed to observe the characteristics and behavior of `sea-quarks' in a proton by reconstructing them from the subatomic particles produced in a collision. The 120 GeV beam from the main injector collides with a fixed target and then passes through a series of detectors which records information about the particles produced in the collision. However, this data becomes meaningful only after it has been processed, stored, analyzed, and interpreted. Several programs are involved in this process. jTracker (sqerp) reads wire or hodoscope hits and reconstructs the tracks of potential dimuon pairs from a run, and Geant4 Monte Carlo simulates dimuon production and background noise from the beam. During track reconstruction, an event must meet the criteria set by the tracker to be considered a viable dimuon pair; this ensures that relevant data is retained. As a check, a comparison between a new version of jTracker and Monte Carlo was made in order to see how accurately jTracker could reconstruct the events created by Monte Carlo. In this presentation, the results of the inquest and their potential effects on the programming will be shown. [Preview Abstract] |
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EA.00028: Measuring the Density of Liquid Targets in the SeaQuest Experiment Zhaojia XI The SeaQuest (E906) experiment, using the 120 GeV proton beam from the Main Injector at the Fermi National Accelerator Lab (FNAL), is studying the quark and antiquark structure of the nucleon using the Drell-Yan process. Based on the cross section ratios, $\sigma(p+d)/\sigma(p+p)$, SeaQuest will extract the Bjorken-x dependnce of the $\bar{d}/\bar{u}$ ratio. The measurement will cover the large region($x>0.25$) with improved accuracy compared to the previous E866/Nusea experiment. Liquid D2 (LD2) and Liquid H2 (LH2) are the targets used in the SeaQuest experiment. The densities of LD2 and LH2 targets are two important quantities for the determination of the $\bar{d}/\bar{u}$ ratio. We measure the pressure and temperature inside the flasks, from which the densities are calculated. The method, measurements and results of this study will be presented. [Preview Abstract] |
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EA.00029: Evidence for High Spin States in $^{70}$Ga C.L. Tan, R.A. Haring-Kaye, K.D. Jones, K.Q. Le, J. D\"{o}ring, B. Abromeit, R. Dungan, R. Lubna, S.L. Tabor, P.-L. Tai, V. Tripathi, J.M. Vonmoss, S.I. Morrow High-spin states in the odd-odd $^{70}$Ga nucleus were populated at Florida State University using the $^{62}$Ni($^{14}$C, $\alpha$pn) fusion-evaporation reaction at a beam energy of 50 MeV. Gamma rays that depopulated the $^{70}$Ga excited states were recorded in coincidence with a Compton-suppressed Ge array consisting of three clover detectors and seven single-crystal detectors. The existing $^{70}$Ga level scheme was modified, enhanced, and extended to higher spin with the addition of eight new transitions based on the analysis of double- and triple-coincidence $\gamma$-ray spectra. Five of these transitions are associated with a new rotational band that may be based on the occupation of the $g_{9/2}$ orbital by the unpaired proton and neutron. The normalized energy differences between adjacent spin states in this new band indicate a signature-splitting pattern that is characteristic of other such bands in neighboring odd-odd nuclei. Similarly, the kinematic moments of inertia deduced for this decay sequence evolve with angular frequency in a manner typical of analogous bands in other odd-odd nuclei in this mass region. [Preview Abstract] |
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EA.00030: Study of $^{162}$Er via the $(p,t)$ and $(p,p^{\prime})$ reactions D. Kisliuk, P.E. Garrett, A. Finlay, L. Bianco, V. Bildstein, C. Burbadge, S. Chagnon-Lessard, A. Diaz Varela, M.R. Dunlop, R. Dunlop, P. Finlay, D. Jamieson, B. Jigmeddorj, A.D. MacLean, J. Michetti-Wilson, K.G. Leach, A.J. Radich, E. Rand, C.E. Svensson, J. Wong, G.C. Ball, S. Triambak, T. Faestermann, R. Hertenberger, H.-F. Wirth The nature of excited states in well-deformed nuclei pose a challenge in nuclear structure. In light of this, the study of $^{162}$Er via the $^{164}$Er$(p,t)$ and $^{162}$Er$(p,p^{\prime})$ reactions has been initiated to shed light on the structure of these excited states. The experiments were performed at the Maier-Leibnitz Laboratory using a 22 MeV proton beam on highly-enriched targets of $^{162,164}$Er and the reaction was analyzed with the Q3D spectrograph. Strong population in the $(p,t)$ reaction of the $0^+_2$ state, far greater than other $0^+$ states, has been observed. Transition matrix elements for population of low-lying states in the $(p,p^{\prime})$ reaction have also been extracted. Initial results from these experiments will be presented. [Preview Abstract] |
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EA.00031: Mu2e Neutron/Gamma Background Analysis Morgan Rosendahl, Mohamed Ahmed, Damien Alexander, Aji Daniel, Ed Hungerford, Mark Sikora In Mu2e, a muon-to-electron conversion experiment that will search for neutrinoless lepton conversion with a single event sensitivity of 10$^{-16}$, a large flux of neutrons with energies less than 10 MeV are emitted after muon capture in the stopping target. These neutrons, and gamma radiation resulting from their absorption, comprise a major component of experimental backgrounds. However, they are not currently sufficiently understood to reliably mitigate single-event-upsets in the readout electronics and time-to-failure of the detector components. At the Paul Scherrer Institute, PSI, a program was undertaken to measure neutron and charged particle emission after muon capture in targets of interest. Two BC501A neutron counters, a Ge, and a LaBr3 detector were used to measure the rates and spectra of emitted neutrons, X-rays, and gammas. The ongoing analysis of this data will provide characterization of the neutron and gamma spectra at low energies. Because the lifetime of a captured muon is nearly a microsecond, the neutron energy spectrum must be determined by unfolding methods. This presentation will discuss the experiment, neutron detector calibrations, and the progress of the analysis. [Preview Abstract] |
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EA.00032: Spin and Isospin Dependent Interactions in Classical Molecular Simulations of Dense Nuclear Matter Charlee Amason, Matt Caplan, CJ Horowitz A neutron star is the hot, incredibly dense remnant of a massive star gone supernova. Extreme conditions on neutron stars allow for the formation of exotically shaped nuclear matter, known colloquially as “nuclear pasta.” Competition between the strong nuclear force and the repulsive Coulomb force results in frustration of the neutron star crust, ultimately resulting in these pasta shapes. Previous work at Indiana University has used classical molecular dynamic simulations to model the formation of this pasta. For this project, we introduce a similar model with a new spin dependent interaction. Using this model, we perform molecular dynamics simulations of both symmetric nuclear matter and pure neutron matter with 400 particles. The energies found are similar to those in chiral effective field theory calculations. When we include Coulomb interactions, the model produces pasta shapes. Future work will incorporate this spin potential into larger pasta simulations. [Preview Abstract] |
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EA.00033: Development of a Rotating Test Mass System for Exotic Spin-Dependent Force Searches Juan Bohorquez, W.M. Snow, Erick Smith, Ben Briggs, Asiyah Din Theories of Physics beyond the Standard Model predict the possibility of a spin-dependent macroscopic force between spin polarized masses and unpolarized masses proportional to $\hat{S}\cdot \hat{r}$ [1]. Previous experiments which bring a non-polarized mass near a polarized mass, and search for NMR frequency shifts have set the best limits on monopole-dipole interactions with matter at distances of one hundred hundred microns to 1 cm. We plan to improve the constraints on these interactions using a spinning test mass near an ensemble of rotating polarized spins produced in a newly-developed spin exchange optical pumping technique [2]. The frequency and phase of the spinning test mass will be chosen to resonantly couple energy into the spin system if there is a monopole-dipole interaction. I will present the designs of the mechanical system that will hold the test mass and the control system that will rotate it at the required rate.\\[4pt] [1] J. Moody and F. Wilczek, Phys. Rev. D (1984).\\[0pt] [2] A. Korver et al, arXiv:1506.08797 (2015) [Preview Abstract] |
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EA.00034: Revival Times for a Generalized Coherent State Katherine Newton, Micheal Berger Revival times are studied for a generalized coherent state found using techniques from supersymmetric quantum mechanics. We prove that in general, exact revivals are quite rare: they only occur when the energy spectrum satisfies a certain condition, namely, that the difference between any two of the energy spectra must be related to the difference between any other two of the spectra by a rational number.. We then examine three examples of shape invariant potentials whose energy spectra satisfy the condition. [Preview Abstract] |
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EA.00035: Simulating Front End Flash in the NO$\nu $A Experiment Jaclyn Schillinger NOvA is an experiment based at Fermilab that aims to learn more about neutrino oscillations. The detectors for NOvA use cells filled with liquid scintillator to observe energy deposited by particles produced in interaction. Groupings of 32 cells connect to a single front end board, FEB, where the electronics are located and which is also connected to a capacitor that is used as ground. Particularly high energy signals can pull charge out of the detector, which causes every channel on that FEB to falsely trigger as the capacitor regains charge, causing a rectangular pattern in the display. This phenomenon, called flash, was an unexpected result of the equipment, and hence was not included in the simulations. I worked to incorporate the flash effect into the simulations used by NOvA, and in the process discovered, elsewhere in the code, an inconsistency between the behavior of the simulation and reality. [Preview Abstract] |
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EA.00036: Development of a Large-Area Ultracold Neutron Detector Jenna Stoffel, Chen-Yu Liu To improve our knowledge in particle physics and cosmology, including big-bang nucleosynthesis, we need a more precise and accurate measurement of the lifetime of free neutrons. Though there have been many attempts to measure the neutron lifetime, discrepancies exist between the two major experimental techniques of the beam and the bottle methods. To resolve this discrepancy, the UCN$\tau $ experiment will trap ultracold neutrons (UCNs) to perform lifetime measurements to the 1-second level. To accomplish this goal, we are developing a large-area, high-efficiency UCN detector. We construct a scintillating UCN detector by evaporating a thin film of boron-10 onto an airbrushed layer of zinc sulfide (ZnS); the $^{10}$B-coated ZnS scintillating film is then glued to wavelength-shifting plastic, which acts as a light guide to direct photons into modern silicon photomultipliers. This new detector has similar efficiency and background noise as the previously-used ion gas detectors, but can be easily scaled up to cover large areas for many applications. The new detector opens up exciting new ways to study systematic effects, as they hold the key to the interpretation of neutron lifetime. [Preview Abstract] |
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EA.00037: Gain Evaluation of Micro-Channel-Plate Photomultipliers in the Upgraded High-B Test Facility at Jefferson Lab Corinne Barber The High-B test facility at Thomas Jefferson National Accelerator Facility allows researchers to evaluate the gain of compact photon sensors, such as Micro-Channel-Plate Photomultipliers (MCP-PMTs), in magnetic fields up to 5 T. These ongoing studies support the development of a Detector of Internally Reflected Cherenkov light (DIRC) to be used in an Electron Ion Collider (EIC). Here, we present our summer 2015 activities to upgrade and improve the facility, and we show results for MCP-PMT gain changes in high B-fields. To monitor the light stability delivered to the MCP-PMTs being tested, we implemented a Silicon Photomultiplier (SiPM) in the setup and calibrated the ADC reading this sensor. A 405-nm Light-Emitting Diode (LED) housed in an optical tube compatible with neutral density filters was also installed. The filters provide an alternative way of reducing the light output of the LED to operate the MCP-PMTs in a single-photon mode. We calibrated a set of filters by means of a photodiode and measured the photon flux at multiple positions relative to the LED. This information helped us to design 3D-printed holders unique to each MCP-PMT so that the photocathode receives the greatest amount of light. The improvements to the setup allow for more precise PMT gain evaluation. [Preview Abstract] |
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EA.00038: Systematics of the Extraction of the Elementary $\gamma $n$\to \pi ^{\mathrm{-}}$p Reaction Cross Sections beyond the Impulse Approximation for $\gamma $d$\to \pi^{\mathrm{-}}$pp Oliver Berroteran, Igor Strakovsky The radiative decay width of neutral baryons may be extracted from $\pi ^{\mathrm{-}}$ and $\pi^{\mathrm{0}}$ photo-production off the neutron, involving a bound neutron target, requiring the use of model-dependent nuclear final state interaction (FSI) corrections. The cross section for the processes $\gamma $n$\to \pi^{\mathrm{-}}$p will be extracted from recent CLAS (E $=$ 400 -- 2500 MeV) and MAX-lab (E $=$ 146 -- 166 MeV) measurements for $\gamma $d$\to \pi^{\mathrm{-}}$pp accounting for Fermi motion effects in the Impulse Approximation (IA) as well as nucleon-nucleon- and pion-nucleon-FSI effects beyond the IA. To test the GW-ITEP FSI code for $\gamma $n$\to \pi^{\mathrm{-}}$p in a reliable way to obtain information \quad on systematics of the extraction of the elementary $\gamma $n$\to \pi^{\mathrm{-}}$p reaction cross sections beyond the IA for $\gamma $d$\to \pi^{\mathrm{-}}$pp, three key factors were chosen and analyzed: (i) The sensitivity to the number of steps of integration for numerical calculations of the five-fold integrals in the determination of FSI amplitudes; (ii) The sensitivity to the alternative deuteron-wave functions. (iii) The sensitivity to the experimental kinematic cut-off of the detected protons (the experimental information is uncertain). Preliminary estimations show that the contribution of all three factors to the overall systematics is less than 4{\%}. [Preview Abstract] |
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EA.00039: Cryotarget Control Software for Liquid Deuterium David Brakman, Gerard Gilfoyle, Chris Cuevas, Steve Christo One of the experiments in Hall B at Jefferson Lab will measure the neutron elastic magnetic form factor with a 12 GeV electron beam striking a liquid deuterium target (LD2) and measuring the resulting debris in the CEBAF Large Acceptance Spectrometer (CLAS12). A program was created that acts as a control system for the LD2 target. It will monitor the deuterium target and send data to the main control system and the shift workers monitoring the experiment in real time. The data include measurements of pressure, temperature, and liquid level. The system will also control setpoints for temperature, heater power, and other parameters as well as download calibration curves. The program was written in LabVIEW, a graphical programming language noted for readily interfacing with lab equipment. This project has completed two stages so far. Simulated data were generated within LabVIEW and passed to subroutines that send, log, and display data on a PC. In the second stage, the PC was connected to a data acquisition board, and test signals were read and analyzed to simulate the target sensors. [Preview Abstract] |
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EA.00040: Niobium Thin Film Characterization for Thin Film Technology Used in Superconducting Radiofrequency Cavities Yishu Dai, Anne-Marie Valente-Feliciano Superconducting RadioFrequency (SRF) penetrates about 40-100 nm of the top surface, making thin film technology possible in producing superconducting cavities. Thin film is based on the deposition of a thin Nb layer on top of a good thermal conducting material such as Al or Cu. Thin film allows for better control of the surface and has negligible response to the Earth's magnetic field, eliminating the need for magnetic shielding of the cavities. Thin film superconductivity depends heavily on coating process conditions, involving controllable parameters such as crystal plane orientation, coating temperature, and ion energy. MgO and Al2O3 substrates are used because they offer very smooth surfaces, ideal for studying film growth. Atomic Force Microscopy is used to characterize surface's morphology. It is evident that a lower nucleation energy and a long coating time increases the film quality in the r-plane sapphire crystal orientation. The quality of the film increases with thickness. Nb films coated on r-plane, grow along the (001) plane and yield a much higher RRR compared to the films grown on a- and c-planes. This information allows for further improvement on the research process for thin film technology used in superconducting cavities for the particle accelerators. [Preview Abstract] |
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EA.00041: Pion Asymmetries due to Hyperon Decays in the Qweak Experiment Jacob Elledge The Qweak experiment took place at the Thomas Jefferson National Accelerator Facility between 2010 and 2012. In the experiment an electron beam was directed onto a liquid hydrogen target. The purpose of the Qweak experiment is to investigate the weak interaction between the proton and the electron. The experiment determined the proton’s weak charge by measuring the asymmetry in elastic scattering when changing the helicity of the incoming electron beam 960 times per second. Under different kinematic conditions the experiment investigated inelastic scattering with pions in the final state, a background for the elastic scattering measurement. In this inelastic measurement, a false asymmetry due to parity-violating hyperon decays must be determined. Using the results of a simulation written in Geant4, I have been able to isolate the cross sections for samples of opposite helicities. By combining this cross section with the signal of detected pions from hyperon decay, I was able to isolate the expected false asymmetry. [Preview Abstract] |
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EA.00042: 3D Printed Scintillators For Use in Field Emission Detection and Other Nuclear Physics Experiments Karen Ficenec In accelerator cavities, field emission electrons – electrons that get stripped away from the cavity walls due to the high electromagnetic field necessary to accelerate the main beam – are partially accelerated and can crash into the cavity walls, adding to the heat-load of the cryogenic system. Because these field electrons emit gamma rays when bent by the electromagnetic field, a scintillator, if made to fit the cavity enclosure, can detect their presence. Eliminating the waste of subtractive manufacturing techniques and allowing for the production of unique, varied shapes, 3D printing of scintillators may allow for an efficient detection system. UV light is used to start a chemical polymerization process that links the monomers of the liquid resin together into larger, intertwined molecules, forming the solid structure. Each shape requires slightly different calibration of its optimal printing parameters, such as slice thickness and exposure time to UV light. Thus far, calibration parameters have been optimized for cylinders of 20 mm diameter, cones of 30 mm diameter and 30 mm height, rectangular prisms 30 by 40 by 10 mm, and square pyramids 20 mm across. Calibration continues on creating holes in the prints (for optical fibers), as well as shapes with overhangs. Scintill [Preview Abstract] |
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EA.00043: Multipass Steering: A Reference Implementation Michael Hennessey, Michael Tiefenback We introduce a reference implementation of a protocol to compute corrections that bring all beams in one of the CEBAF linear accelerators (linac) to axis, including, with a larger tolerance, the lowest energy pass using measured beam trajectory data. This method relies on linear optics as representation of the system; we treat beamline perturbations as magnetic field errors localized to regions between cryomodules, providing the same transverse momentum kick to each beam. We produce a vector of measured beam position data with which we left-multiply the pseudo-inverse of a coefficient array, A, that describes the transport of the beam through the linac using parameters that include the magnetic offsets of the quadrupole magnets, the instrumental offsets of the BPMs, and the beam initial conditions. This process is repeated using a reduced array to produce values that can be applied to the available correcting magnets and beam initial conditions. We show that this method is effective in steering the beam to a straight axis along the linac by using our values in elegant, the accelerator simulation program, on a model of the linac in question. The algorithms in this reference implementation provide a tool for systematic diagnosis and cataloging of perturbations in the beam line. [Preview Abstract] |
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EA.00044: Phi Photoproduction Cross Section and Spin Density Matrix Elements Using CLAS g12 Data Andrew Hurley Photoproduction experiments, in complement with nucleon deep inelastic scattering experiments, seek to better understand the spectrum of excited baryons, as well as the structure and QCD interactions of the quarks and gluons inside them. In recent years, the amount (and quality) of data for light-meson photoproduction has grown and expanded into higher energies. The production of vector mesons is particularly interesting because photons have the same spin-parity ($J^P = 1^-$) as vector mesons such as $\rho$, $\omega$, and $\phi$. The decay of excited baryons into vector mesons is also largely underexplored; however, the study of such decay modes --in addition to the better known decays into pseudoscalar mesons-- is necessary to establish the existence of a baryon resonance. Out of the vector meson decays, the reaction $\gamma p\to p\phi$ has been studied the least. Here we analyze the aforementioned decay by using data taken at Jefferson Laboratory with the CEBAF Large Acceptance Spectrometer (CLAS) at energies from the reaction threshold to 5.5~GeV. Using the data for $p\,K^+ K^?$ final states (since $\phi\to K^+ K^-$ with a $\sim 49\,\%$ branching fraction), a cross section for this decay mode and elements of the spin-density matrix have been determined. [Preview Abstract] |
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EA.00045: Bench Tuning of the 748.5 MHz Normal Conducting Separator Cavities for 4-Hall Beam Delivery Andrew Jacobs The 748.5 MHz cavities (or the 750 MHz cavities for short) were installed at CEBAF as part of the 12 GeV upgrade. The cavity is composed of two different cells. In each cell there are 4 copper rods, a tuning paddle, and a field probe. In one cell, a coupler antenna is inserted in the form of a copper loop. These components then work together to create an RF field that kicks electron bunches. The goal of these separator cavities was to split the electron beam so that simultaneous 4-hall beam delivery was possible. For bench tuning of the cavities, three parameters must be achieved: target operational frequency, critical coupling, and field flatness between each cell. The initial problem was that when the cavities were installed, it wasn't possible to optimize the three parameters by only controlling the cooling water temperature during the commissioning. Thus, the four 750 MHz cavities were uninstalled and underwent bench tuning. This was done through bead-pull testing, computer simulations, and off-line high power testing. The tuning procedure developed allows for all three parameters to be met. Therefore the cavities will be able to be reinstalled in the beam-line and enable 4-hall beam delivery. [Preview Abstract] |
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EA.00046: Electron Beam Focusing in the Linear Accelerator (linac) Luis Jauregui To produce consistent data with an electron accelerator, it is critical to have a well-focused beam. To keep the beam focused, quadrupoles (quads) are employed. Quads are magnets, which focus the beam in one direction (x or y) and defocus in the other. When two or more quads are used in series, a net focusing effect is achieved in both vertical and horizontal directions. At start up there is a 5{\%} calibration error in the linac at Thomas Jefferson National Accelerator Facility. This means that the momentum of particles passing through the quads isn't always what is expected, which affects the focusing of the beam. The objective is to find exactly how sensitive the focusing in the linac is to this 5{\%} error. A linac was simulated, which contained 290 RF Cavities with random electric fields (to simulate the 5{\%} calibration error), and a total momentum kick of 1090 MeV. [Preview Abstract] |
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EA.00047: Studies of Multi-Anode PMTs for a Ring Imaging Cherenkov for CLAS12 Andrew Lendacky, Fatiha Benmokhtar, Valery Kubarovsky, Andrey Kim At Thomas Jefferson National Accelerator Facility (TJNAF), the CLAS12 detector in Hall B is undergoing an upgrade. A Ring Imaging Cherenkov (R.I.C.H) detector is being built to improve particle identification in the 3-8 GeV/c momentum range. Approximately four hundred Hamamatsu H121700 Multi-Anode Photomultiplier Tubes (MA-PMTs) are being used in this detector to measure photons emitted through Cherenkov Radiation. These MA-PMTs' characteristics are being tested and measured, and I will be presenting my work about the crosstalk study. Crosstalk is the occurrence of incident light striking one area of the photocathode, but is additionally measured in nearby areas. By using a Class 3b laser in the 470 nm wavelength, and an optical density resembling the single photon emission spectrum, the crosstalk for the H121700 MA-PMTs are measured and categorized into a database for future reference. [Preview Abstract] |
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EA.00048: Characterizing Properties and Performance of 3D Printed Plastic Scintillators Jacob McCormick We are determining various characteristics of the performance of 3D printed scintillators. A scintillator luminesces when an energetic particle raises electrons to an excited state by depositing some of its energy in the atom. When these excited electrons fall back down to their stable states, they emit the excess energy as light. We have characterized the transmission spectrum, emission spectrum, and relative intensity of light produced by 3D printed scintillators. We are also determining mechanical properties such as tensile strength and compressibility, and the refractive index. The emission and transmission spectra were measured using a monochromator. By observing the transmission spectrum, we can see which optical wavelengths are absorbed by the scintillator. This is then used to correct the emission spectrum, since this absorption is present in the emission spectrum. Using photomultiplier tubes in conjunction with integration hardware (QDC) to measure the intensity of light emitted by 3D printed scintillators, we compare with commercial plastic scintillators.~We are using the characterizations to determine if 3D printed scintillators are a viable alternative to commercial scintillators for use at Jefferson Lab in nuclear and accelerated physics detectors. [Preview Abstract] |
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EA.00049: Characterization of Lead Tungstate for Neutral Particle Spectrometer at 12GeV JLab Christian Runyon Precision measurements of the deeply-virtual Compton scattering cross section at different beam energies to extract the real part of the Compton form factor, measurements to push the energy scale of real Compton scattering, and measurements of the basic semi-inclusive neutral-pion cross section in a kinematical region where the QCD factorization scheme is expected to hold all have something in common: the need for detecting neutral particles with high precision and high luminosity. The Neutral Particle Spectrometer (NPS) is a crystal electromagnetic calorimeter preceded by a sweeping magnet to sweep away charged particles. In this presentation I will show the results of PbWO$_{4}$ crystal quality studies for the NPS. PbWO4 is optimal for the NPS due to its small Moliere radius and radiation hardness. The critical aspect for crystal quality, and thus resolution/precision, is the combination of high light output and radiation hardness, which depend strongly on the manufacturing process. We have tested the performance of PbWO$_{4}$ crystals, and in particular, measured their light yield, optical transmission, and uniformity and radiation hardness. The homogeneity of the crystal was investigated based on the variation of the transverse optical transmission. [Preview Abstract] |
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EA.00050: Dual Species Noble Gas Nuclear Spin Polarizer for a New Search for the Atomic EDM of Xe-129 at FRM-II (Munich Research Reactor) Jared Cohn, Daniel Coulter, Dustin Frisbie, Steven Fromm, Jake Huneau, Tenzin Rabga, Walter Underwood, Jaideep Singh, Peter Fierlinger, Eva Kraegeloh, Florian Kuchler, Tobias Lins, Mike Marino, Jonas Meinel, Benjamin Neissen, Stefan Stuiber, Isaac Fan, Wolfgang Kilian, Silvia Knappe-Gruenberg, Lutz Trahms, Tim Chupp, Skyler Degenkolb, Natasha Sachdeva, Fei Gong, Earl Babcock Electric dipole moments are believed to be very sensitive probes of CP violation beyond the Standard Model. A new search for the atomic electric dipole moment of Xe-129 is currently underway at FRM-II in Munich. Our technique takes advantage of a state of the art magnetically shielded room, ultra-sensitive magnetometry using SQUIDs, and control of systematics using a He-3 co-magnetometer. Our goal is an order of magnitude improvement over the previous Xe-129 atomic EDM limit. We will describe the design and construction of a noble gas polarizer using spectrally-narrow diode lasers. [Preview Abstract] |
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EA.00051: Simulation of a pion trigger for E12-06-114 J. Adams Theibert The Deeply Virtual Compton Scattering (DVCS) experiment\footnote{ http://inspirehep.net/record/725912} E12-06-114 at Jefferson Lab in Hall A will be taking data in 2016. Measurements of the absolute cross section of the H(e, e$'$ $\gamma$)p will provide information about the internal structure of the nucleon. Photons resulting from the decay of $\pi^0$ are the main source of background. A means of isolating the $\pi^0$ reactions through modification of the dedicated FPGA based trigger function can help remove this unwanted background. Preliminary tests of the modified trigger in a simulated experiment show this approach has the capability of refining data acquisition. [Preview Abstract] |
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EA.00052: RICH Detector for Jefferson Labs CLAS12 Richard Trotta, Ben Torisky, Fatiha Benmokhtar Jefferson Lab (Jlab) is performing a large-scale upgrade to~its Continuous Electron Beam Accelerator Facility (CEBAF) up to 12GeV beams. The Large Acceptance Spectrometer (CLAS12) in Hall B is being upgraded and a new hybrid Ring Imaging Cherenkov (RICH) detector is being developed to provide better kaon -- pion separation throughout the 3 to 8 GeV/c momentum range. This detector will be used for a variety of Semi-Inclusive Deep Inelastic Scattering experiments. Cherenkov light can be accurately detected by a large array of sophisticated Multi-Anode Photomultiplier Tubes (MA-PMT) and heavier particles, like kaons, will span the inner radii.~We are presenting our work on the creation of the RICH's geometry within the CLAS12 java framework. This development is crucial for future calibration, reconstructions and analysis of the detector. [Preview Abstract] |
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EA.00053: UCNA Field Profile Analysis Brian Allgeier, Brad Plaster, Michael Brown The UCNA experiment, located at the Los Alamos Neutron Science Center (LANSCE), is the first of its kind, using ultra-cold neutrons (UCN) to measure the neutron $\beta$-decay asymmetry parameter $A_0$. This coefficient is a measure of the correlation between a neutron's spin and the decay electron's emission direction. An accurate extraction of such a parameter allows for significant consequences in the understanding of weak interactions. UCNA implements a 1 T superconducting solenoid to send decay electrons toward detectors at either end of the experimental cylinder. The magnetic field strength as a function of position along the length of the cylinder (the field profile) plays an important role in the movement of these electrons. A $\sim$0.5\% dip in strength near the center of all field profiles allows for the deflection or entrapment of a small yet significant fraction of decay electrons. Such a phenomenon leads to a potential false asymmetry to be measured in UCNA, depending upon the shape of the field profile during experimentation. Monte Carlo simulations were used to generate large data sets of $\beta$-decay events in various field profiles. The focus of this work is to analyze the effects of the best and worst field profiles on the asymmetries measured by the UCNA experiment. [Preview Abstract] |
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EA.00054: MCNP Neutron Simulations: The Effectiveness of the University of Kentucky Accelerator Laboratory Pit Daniel Jackson, Thien An Nguyen, S.F. Hicks, Ben Rice, J.R. Vanhoy The design of the Van de Graaff Particle Accelerator complex at the University of Kentucky is marked by the unique addition of a pit in the main neutron scattering room underneath the neutron source and detection shielding assembly. This pit was constructed as a neutron trap in order to decrease the amount of neutron flux within the laboratory. Such a decrease of background neutron flux effectively reduces as much noise as possible in detection of neutrons scattering off of desired samples to be studied. This project uses the Monte-Carlo N-Particle Transport Code (MCNP) to model the structure of the accelerator complex, gas cell, and the detector's collimator and shielding apparatus to calculate the neutron flux in various sections of the laboratory. Simulations were completed with baseline runs of 10$^{7}$ neutrons of energies 4 MeV and 17 MeV, produced respectively by $^{3}$H(p,n)$^{3}$He and $^{3}$H(d,n)$^{4}$He source reactions. In addition, a comparison model of the complex with simply a floor and no pit was designed, and the respective neutron fluxes of both models were calculated and compared. The results of the simulations seem to affirm the validity of the pit design in significantly reducing the overall neutron flux throughout the accelerator complex, which could be used in future designs to increase the precision and reliability of data. [Preview Abstract] |
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EA.00055: Neutron Scattering Simulations at the University of Kentucky Accelerator Laboratory ThienAn Nguyen, Daniel Jackson, S.F. Hicks, Ben Rice, J.R. Vanhoy The Monte-Carlo N-Particle Transport code (MCNP) has many applications ranging from radiography to reactor design. It has particle interaction capabilities, making it useful for simulating neutron collisions on surfaces of varying compositions. The neutron flux within the accelerator complex at the University of Kentucky was simulated using MCNP. With it, the complex's capabilities to contain and thermalize 7 MeV neutrons produced via $^{2}$H(d,n)$^{3}$He source reaction to an acceptable level inside the neutron hall and adjoining rooms were analyzed. This will aid in confirming the safety of researchers who are working in the adjacent control room. Additionally, the neutron transport simulation was used to analyze the impact of the collimator copper shielding on various detectors located around the neutron scattering hall. The purpose of this was to attempt to explain any background neutrons that are observed at these detectors. The simulation shows that the complex performs very well with regards to neutron containment and thermalization. Also, the tracking information for the paths taken by the neutrons show that most of the neutrons' lives are spent inside the neutron hall. Finally, the neutron counts were analyzed at the positions of the neutron monitor detectors located at 90 and 45 degrees relative to the incident beam direction. [Preview Abstract] |
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EA.00056: Measuring Neutron-Proton Radiative Capture Cross-section at Low Energy To Chin Yu, Michael Kovash, June Matthews, Hongwei Yang, Yunjie Yang The experiment aims to fill in a gap in our data for the cross-section of neutron-proton radiative capture (p(n,d$\gamma$)) at energies below 500 keV. Current measurements in this energy range are scarce and inconsistent with theoretical predictions and with each other. A well-determined cross-section of the capture reaction in the low energy range is useful in nuclear physics due to its fundamental nature. The measurement is also of interest in cosmology. Big Bang Nucleosynthesis (BBN), the process by which light elements are formed in early universe, is very sensitive to the p(n,d$\gamma$) cross-section in the low energy range. The measurement enables us to put tighter constraints on the theoretical predictions of BBN. We have conducted preliminary measurements in the van de Graaff accelerator facility at the University of Kentucky. Our array of detectors consists of three plastic scintillators to serve as proton targets and deuteron detectors, and five BGO scintillators to detect $\gamma$-rays. The combination results in an over-determination of reaction kinematics that discriminates against scattering processes and other backgrounds. We have obtained some early results which show promise for the precise measurement of the p(n,d$\gamma$) cross-section. [Preview Abstract] |
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EA.00057: Elastic and Inelastic Scattering of Neutrons using a CLYC array Tristan Brown, E. Doucet, P. Chowdhury, C.J. Lister, G.L. Wilson, M. Devlin, S. Mosby CLYC scintillators, which have dual neutron and gamma response, have recently ushered in the possibility of fast neutron spectroscopy without time-of-flight (TOF) [1-3]. A 16-element array of 1" x 1" 6Li-depleted CLYC crystals, where pulse-shape-discrimination is achieved via digital pulse processing, has been commissioned at UMass Lowell. In an experiment at LANSCE, high energy neutrons were used to bombard 56Fe and 238U targets, in order to measure elastic and inelastic neutron scattering cross sections as a function of energy and angle with the array. The array is placed very close to the targets for enhanced geometrical solid angles for scattered neutrons compared to standard neutron-TOF measurements. A pulse-height spectrum of scattered neutrons in the detectors is compared to the energy of the incident neutrons, which is measured via the TOF of the pulsed neutrons from the source to the detectors. Recoil corrections are necessary to combine the energy spectra from all the detectors to obtain angle-integrated elastic and inelastic cross-sections. The detection techniques, analysis procedures and results will be presented.\\[4pt] [1] N. D'Olympia et al., NIM A694, 140 (2012);\\[0pt] [2] N. D'Olympia et al., NIM A714, 121 (2013);\\[0pt] [3] N. D'Olympia et al., NIM A763, 433 (2014) [Preview Abstract] |
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EA.00058: Fast Neutron Spectroscopy using a CLYC array Emery Doucet, T. Brown, P. Chowdhury, C.J. Lister, G.L. Wilson, M. Devlin, S. Mosby A new inorganic scintillator, Cs$_{2}$LiYCl$_{6}$, or CLYC, has recently shown great promise as a dual gamma-neutron detector [1-3], where neutron-gamma discrimination is achieved through digital pulse shape processing. The $^{35}$Cl(n,p) reaction allows fast neutrons to be measured with an energy resolution of $\approx$10$\%$. Following initial tests with natural Li, $^{6}$Li-depleted crystals were chosen to reduce the strong thermal capture response of $^{6}$Li. A 16-element array of 1" x 1" $^{6}$Li-depleted CLYC crystals is being tested in a variety of applications. A VME-based digital DAQ is used for pulse shape discrimination and extracting energies. The array was deployed at the LANSCE WNR facility, to measure elastic and inelastic scattering cross sections of neutrons on $^{56}$Fe and $^{238}$U. The data acquisition and analysis software were originally based on Python. The sorting codes were re-written in C, which sped up the analysis by two orders of magnitude. Most of the sorting code is within the framework of the CERN-ROOT software. Details of the detector array and the analysis will be presented.\\[4pt] [1] N. D'Olympia et al., NIM A694, 140 (2012);\\[0pt] [2] N. D'Olympia et al., NIM A714, 121 (2013);\\[0pt] [3] N. D'Olympia et al., NIM A763, 433 (2014). [Preview Abstract] |
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EA.00059: Paschen Curve Observations at Liquid Nitrogen Temperatures Chip Dugger, Keith Rielage, Steven Elliott, Ralph Massarczyk, Pinghan Chu Paschen's Law states an equation giving the relationship between variables involved when forming an electrical arc between two conductive objects, otherwise known as the breakdown voltage. This equation for the breakdown voltage $V_B$ is as follows: \begin{equation} V_B=\frac{apd}{\ln{(pd)}+b} \end{equation} where $p$ is the pressure in Atmospheres (or Bar), $d$ is the gap or distance between the two conductive objects, and both $a$ and $b$ are constants that depend on the composition of the gas. In our experiment, the Paschen curve for gases (such as nitrogen) at temperatures lower than -200 degrees Celsius will be measured. The Paschen curve for air at room temperature will also be measured in order to test and calibrate our system. The goal of this experiment is to test how accurately Paschen's Law can predict the breakdown voltage in these specific, cold conditions. This experiment is being performed to gather information for a possible future experiment, which might use high purity germanium (HPGe) detectors in a similar cold environment to search for neutrinoless double beta decay, a rare hypothesized process that may yield valuable insight into the fundamental properties of the neutrino. This work is being supported by the DOE through the LANL LDRD program. [Preview Abstract] |
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EA.00060: Neutrino Cross Section For Interaction With Helium-4 Nuclei George K. Fuller, Anna C. Hayes, Gerald M. Hale Using updated calculations of the energy eigenstates of the $^4$He nucleus and the no core shell model of atomic nuclei, we have produced a more accurate calculation of the cross section for interaction between neutrinos/antineutrinos and $^4$He for both neutral- and charged-current interactions. Previous calculations of this cross section were performed by only taking into account the strong contribution from Gamow-Teller transitions and neglecting the higher-order operators which allow transitions to other states. The Gamow-Teller-only approximation for the neutrino cross section is efficacious for the needs of most Standard Model Big Bang nucleosynthesis calculations, where the neutrino cross section of $^4$He is not a significant contributor to neutron and deuterium abundance. However, using the Gamow-Teller-only approximation strains the bounds on the accuracy needed by newer calculations which aim to include Beyond-Standard Model effects for reproducing precise cosmological data. By including all energy eigenstates in the calculation and including the effects from the energy widths of each state, we can provide a neutrino energy-dependent $^4$He cross section which meets these higher needs of precision. [Preview Abstract] |
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EA.00061: Magnetic Mapping of the UCN$\tau$ Apparatus Rowan Lumb The lifetime of free neutron decay has been determined by two different experimental techniques that differ in reported values by about 8~s, while individual experiments report an error of about 1~s. The UCN$\tau$ collaboration has an immediate goal to measure the lifetime of the neutron to within 0.1\%, i.e. about 1~s, using an apparatus that addresses systematic effects in previous experiments by confining the neutrons with a magnetic field. The UCN$\tau$ apparatus is a magneto-gravitational trap capable of holding polarized low-energy ($\sim$100 neV) ``ultracold'' neutrons (UCN) in a magnetic ``bowl'' with the help of gravity. The trap is composed of a discrete Halbach permanent magnet array as well as a number of normally conducting field coils that wrap around the array itself. The array produces an exponentially decaying magnetic field capable of trapping the UCN, while the coils create a holding field that inhibits depolarization. However, there is concern over whether mechanical defects might cause cancellation between the two field sources. If cancellation does occur within the trap, magnetic field zeros or uncontrolled field gradients could result, which could increase the depolarization rate. In response, we are performing a surface mapping of the array using a three-axis Hall probe, as well as a volume mapping of the holding field to search for any cancellations or inconsistencies that would create a systematic error in the experiment. We will also report on a stereo tracking system designed to allow precise measurement of the probe's position in real-time within the array. [Preview Abstract] |
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EA.00062: Digital Acquisition Development for Fast Neutron Detectors T. Seagren, S. Mosby The use of the Modular Neutron Array (MoNA) at FRIB requires a thorough understanding of how neutrons propagate through the array. This leads to the increasing importance of accuracy in detector response simulations, particularly in the case of FRIB's higher beam energies. An upcoming experiment at the LANSCE facility at Los Alamos National Lab will benchmark neutron propagation through the MoNA array and provide a more complete validation of the simulation software. LANSCE also hosts the Chi-Nu experiment, which seeks to measure fission output neutrons using the high-intensity neutron beams there. In both experiments, the instantaneous rate on the detectors involved is expected to be very high, due to the LANSCE/WNR beam structure. Therefore, waveform digitizers with on-board processing are required in order for the experiments to succeed. These digitizers provide on-board timing algorithms using FPGA firmware, and several tests were preformed in order to determine what the optimal timing filter settings were for a variety of detectors, including the plastic and liquid scintillators to be used in MoNA and Chi-Nu respectively. This work will inform the execution of the MoNA and Chi-Nu experiments at LANSCE. The details of the methods used and results will be presented. [Preview Abstract] |
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EA.00063: Effects of Recent Reactor Anti-neutrino Spectra on Neutrino Oscillations Ciara Sterbenz The $\beta$-decay of nuclear fission fragments produces a very large $\overline{\nu}_e$ flux from nuclear reactions. The shape of the expected flux has previously been predicted by converting the measured $\beta$-electron spectrum to an $\overline{\nu}_e$ spectrum. Recent reactor neutrino experiments, however, find a large shoulder in the observed $\overline{\nu}_e$ spectrum relative to this prediction in the energy region 5 - 7 MeV. Accurate knowledge of the expected $\overline{\nu}_e$ flux from reactors is important for oscillation experiments that only involve one neutrino detector. In this project, I examine the implications of these spectral changes on the $\nu$ oscillation result found by the KamLAND experiment. At the time of their finding, the spectral anomaly from 5 - 7 MeV had not be observed. I have re-derived the oscillation parameters $\Delta m^2$ and $sin^2(2\theta)$ using the anti-neutrino flux from Daya Bay and from nuclear database predictions. With these new expected fluxes, these oscillation parameters shifted and their uncertainties increased. I compare the new oscillation parameters with those derived from solar neutrino oscillation data. [Preview Abstract] |
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EA.00064: Modeling of ultracold neutron motion within the UCN$\tau$ magneto-gravitational trap Douglas Wong The UCN$\tau$ experiment at the Los Alamos Neutron Science Center (LANSCE) measures the lifetime of free ultra cold neutrons (UCN). The neutrons are trapped within an asymmetric compound toroidal bowl made of a Halbach array of permanent magnets. The storage time $\tau_{store}$ of the trap is then measured by storing UCNs for various times before counting the remaining neutrons. The asymmetry of the trap is designed such that a population of UCNs should fill phase space with chaotic orbits, allowing the detector to count surviving neutrons with efficiency independent of storage time. This project seeks to verify that the simplest possible model of orbits in a compound toroid indeed produces chaotic orbits. We will also investigate if the chaotic nature of the phase space evolution is dependent on whether a neutron's interaction with the walls of the trap is modeled as a magnetic interaction or as simple specular reflection from a hard surface. The presented talk will include a status report. [Preview Abstract] |
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EA.00065: Dead Layer Measurement in P-type Point Contact Germanium Detectors for the {\sc Majorana Demonstrator} Sophia Elia The {\sc Majorana Demonstrator} will search for the neutrinoless double beta decay ($0\nu\beta\beta$) of the isotope $^{76}$Ge. In anticipation of the future large-scale experiments, its goal is to demonstrate a path forward to a background rate of one cnt/(ROI-t-y) in a 4 keV region around the Q-value of the \(^{76}\)Ge $0\nu\beta\beta$. The {\sc Majorana Demonstrator} consists of an array of high purity germanium detectors arranged in strings. Before installation in the cryostat, each string has been characterized. A vertical scan along the string \mbox{(Z-scan)} using radioactive sources is performed to measure the dead layer of each detector while an azimuthal scan is taken to measure the orientation of the crystal axes, useful for axion physics. Understanding the dead layer of the crystals is crucial to precisely determine the effective mass of the detectors. This poster presents Z-scan measurements and data analysis. The dead layer determination obtained through detailed comparison of simulation and data will be discussed. [Preview Abstract] |
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EA.00066: Latchup Tests on pALPIDEfs Elad Michael In 2018, the ALICE ITS will be upgraded to keep up with new beam requirements. ALPIDE is one of the proposed silicon pixel detector designs; However, the pixel design suffers from a side effect called latch-up. Latchup is inevitable with transistors on such small scale, but it can be minimized if the silicon is designed well. The goal of this experiment is to quantify the probability of latch-up in ALPIDE for different particle cocktails and pixel geometries, to determine the viability of the design. The chip records two currents, from different silicon blocks; when either current rises above a user-set threshold the latchup power cycle process begins. The waveforms began in one of two general shapes, determined by the areas of the sensor that were latching up, but after a potentially damaging event there were several other waveforms that developed, which may have some indication to the damage done to the chip. To attempt to differentiate data that was effected by the damage, a machine learning algorithm using logistic regression was implemented to sort the current waveforms recorded during testing. The algorithm successfully categorizes latchups in 4 different categories, 2 categories of good data, and two particularly frequent categories of damaged waveform. [Preview Abstract] |
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EA.00067: Testing new designs for the {\sc{Majorana Demonstrator's}} low-mass front-end board Chiara Salemi The {\sc{Majorana Demonstrator}} is searching for neutrinoless double-beta decay in \textsuperscript{76}Ge p-type point contact (PPC) detectors in order to determine if a neutrino is its own antiparticle and to probe the absolute neutrino mass scale. Finding this rare decay would also show that lepton number is not conserved. The search is made possible by the novel high-purity Ge PPC detector technology, which allows a low energy threshold and excellent energy resolution. Rare event searches with such sensitive detectors require extremely low radioactive backgrounds, and the front-end electronics, located inside the shielding, are one of the primary sources of background events in the signal region. For this reason, the front-end board is made to be low-mass and of radio-pure materials. A new design that is being studied could potentially in the future replace the board's fused silica substrate with a copper back plane coated in parylene, two materials whose assay results show low radioactivity. In addition to decreasing the overall radioactivity of the board, the new design reduces the amount of material near the detectors. Preliminary testing shows that the new design also substantially decreases the intrinsic electronic noise of the signal amplification circuitry. [Preview Abstract] |
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EA.00068: Low Transverse Momentum \emph{K}$_S$ Production in Au + Au Collisions at $\sqrt{s_{NN}}$ = 200 GeV Zhaozhong Shi The Heavy Flavor Tracker (HFT) detector installed in the STAR experiment is aimed for precision measurement of charm production in heavy-ion collisions by topologically reconstructing the secondary decays of charmed hadrons. With the significantly improved pointing resolution enabled by the HFT, we can also reconstruct low transverse momentum (\emph{p}$_T$ $<$ 0.3 GeV/c) \emph{K}$_S$ particles that decay very close to collision vertices, which was difficult before with the Time Projection Chamber (TPC) only. Measurement of the low transverse momentum yield will further constrain the total kaon yield in the full kinematic phase space. In this presentation, we will present the first measurement of the \emph{K}$_S$ production focusing on the low transverse momentum region (\emph{p}$_T$ $<$ 0.3 GeV/c) with the HFT detector from Au + Au collisions at $\sqrt{s_{NN}}$= 200 GeV. We will report the invariant yield and elliptic flow vs. \emph{p}$_T$ in different centrality bins. The results will be compared with previous measurements at RHIC. [Preview Abstract] |
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EA.00069: Characterization of Single Event Latchup Cross-Section for ALPIDE Joanna Szornel, Elad Michael, Fernando Torales - Acosta, Leo Greiner, Barbara Jacak Latchup cross-section was characterized for a prototype of ALPIDE (ALICE PIxel DEtector), a silicon pixel detector proposed for use in the ALICE inner tracking system. Before being implemented, the sensor needs to be tested to verify its effectiveness. When active it will be subject to bombardment from energetic ions which can cause single event latchups (SELs). These occur when parasitic effects result in short-circuits, causing potentially damaging increases in current. Ions with various LETs (5 - 40 MeV) were used to induce SELs whereupon event cross-section was measured. The likelihood of the sensor experiencing SEL increases with greater ion LET and fluence. [Preview Abstract] |
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EA.00070: Characterization of Single Event Latch-Up Cross Section in Prototype ALPIDE Sensor Fernando Torales - Acosta Particles containing heavy quarks are excellent probes into the full evolution of QGP, and the Inner Tracking System (ITS) of ALICE is responsible for detecting these short-lived heavy particles by measuring their impact parameter, the point at which they decay relative to the initial collision. ALPIDE is a next generation monolithic active pixel sensor (MAPS) designed for the ALICE ITS upgrade in 2018 that would increase the impact parameter resolution and readout speed of the ITS. Like most silicon using CMOS technology, however, ALPIDE can suffer from single event latch-up. The aim of this experiment was to measure the cross section of latch-up in a prototype ALPIDE sensor using the 88" cyclotron facility at Lawrence Berkeley National Laboratory. High statistics in a range of ions with low linear energy transfers (LETs) were needed to characterize the onset curve of latch-up in the sensor. It was found that latch-up occurred with reasonable statistics at LETs as low as 5 MeV/(mg/cm$^2$). The sensor, however, undergoes a power cycle after each latch-up. As a result, significant dead time correction was required for accurate calculation of the sensor's cross section. Potential damage to the sensor from a particularly strong latch-up was also observed. [Preview Abstract] |
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EA.00071: Thermodynamics and jet-quenching in the quark-gluon plasma from an AdS/QCD model Elias Lilleskov, Sean Bartz The Anti-de Sitter Space/Conformal Field Theory Correspondence (AdS/CFT) has been used to study both hadronic dynamics and the thermodynamics and jet quenching behavior of the quark-gluon plasma created in heavy ion collisions. We attempt to connect the two regimes by adapting an AdS/QCD model previously used to study meson spectra to apply to the quark-gluon plasma. The model includes three fields: a dilaton to introduce confinement, and chiral and glueball condensates to reflect the zero-temperature dynamics. We dynamically solve the Einstein field equations to numerically determine the metric, which asymptotically describes an anti-de Sitter-Schwarzschild black hole solution. We then numerically calculate the temperature as a function of the black hole horizon location. Next, we determine the behavior of the entropy density, the speed of sound, and the jet quenching parameter as functions of the temperature. These quantities approach the behavior of a conformal plasma in the high temperature limit. The minimum of the temperature-horizon plot is interpreted as the plasma's deconfinement temperature, found to be 104 MeV. [Preview Abstract] |
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EA.00072: Dijet asymmetry based on an analytic Glauber model and path length dependent energy loss computations in Pb+Pb collisions Daniel Miron, Brian Cole Preliminary ATLAS results from Pb+Pb collisions at $\sqrt{s_{NN}} = 2.76$ TeV show a dependence of the dijet asymmetry on the angle $(\Delta \phi)$ of the leading jet with respect to the event plane on the order of 2-3\% for mid-range centrality collisions. Using an analytic Glauber model to simulate heavy ion interactions, we computed path length dependent energy loss for simulated dijet events in Pb+Pb collisions, with initial energy and parton flavors determined based on PYTHIA calculations of p+p collisions. We observe a $\Delta \phi$ and impact parameter dependent behaviour similar to that observed in the experiment. We also show that this $p_T$-independent energy loss is not sufficient to reproduce the single jet nuclear modification factor $(R_{AA})$ in the same Pb+Pb collisions and look into more accurate $p_T$-dependent energy loss based on the BDMPS formalism. [Preview Abstract] |
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EA.00073: Monte Carlo Study of Quark \& Gluon Jets at $\sqrt{s}=2.76\ \& \ 7$ TeV With Inclusive Jet Comparison to ATLAS Measurements Matthew Mistro In the study of heavy ion collisions, $pp$ collisions are a necessity of understanding as a baseline due to producing minimal hot dense matter. Different Monte Carlo simulations with various tunes are studied for these $pp$ collisions at $ \sqrt{s}=2.76 \ \& \ 7 $ TeV. The primal focus being on the charged multiplicity as a function of the ratio of the charged particles transverse momenta, $ p_T^{ch} $, to the originating jet transverse momentum, $ p_T^{jet} $, referred to as $ z $. As they cannot directly be seen at the LHC, simulations find the differences of said functions to originating from a quark or gluon jet for varied $ p_T^{jet} $ cuts of $ 40 < p_T^{jet} < 260 $ GeV. The inclusive fragmentation functions are compared to measurements from the ATLAS collaboration, and simulation based solutions to isolating quark jets via photon processes are compared to that of hard QCD quark jets. [Preview Abstract] |
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EA.00074: Modeling Meson and Glueball Spectra using the AdS/QCD Correspondence Joshua Rollag, Sean Bartz AdS/QCD is a proposed duality between strongly-coupled quantum chromodynamics theories and weakly-coupled gravitational theories in an additional dimension that can offer new insight to hadronic physics. Previous work has accurately modeled confinement and chiral symmetry breaking while also including the glueball field. This project focuses on accommodating recent COMPASS results, which indicate a new light axial-vector resonance that falls between the ground state and the currently-accepted value for the first excited state. In addition, we complete the three-field AdS/QCD model by analyzing the scalar meson and glueball spectra to a first-order approximation. The meson results match experimental data well. However, we show that a model with a single mass scale cannot accommodate the current lattice results for the glueball spectrum. [Preview Abstract] |
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EA.00075: Jet-Track Correlation Analysis of Monte Carlo Simulated Data for the CMS Experiment William Tabb, Olga Evdokimov Collisions of ultra-relativistic heavy ion beams delivered at the Large Hadron Collider (LHC) and the Relativistic Heavy Ion Collider (RHIC) are used to study the properties of a special form of nuclear matter, termed Quark Gluon Plasma (QGP). Among the experimental tools actively employed to explore the QGP properties, are jets -- collimated streams of particles produced from hard-scattered partons in the initial state of the collision. The hot and dense medium produced in heavy ion collisions interacts strongly with the partons traversing it, resulting in energy loss and modifications to the momentum distributions of the forming jets. A development of the jet-track correlation analysis was performed and tested with Monte Carlo (MC) data samples simulating jet data for the CMS experiment at LHC, allowing study of several jet-related properties in order to better understand the medium effects on penetrating probes. [Preview Abstract] |
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EA.00076: Simulated Optimization of HFE Volume around the nEXO TPC Mitchell Negus, Samuele Sangiorgio nEXO is a leading contender in the next generation of neutrinoless double beta decay (0$\nu \beta \beta )$ \quad detectors. Given the extreme rarity of 0$\nu \beta \beta $, with a half-life measured to be no less than 10$^{25}$ years by EXO-200, and both spatial and energy resolution limits of the large nEXO time projection chamber (TPC), controlling backgrounds near the 0$\nu \beta \beta $ Q-value is critical. Conveniently, the hydrofluoroether (HFE) fluid which insulates the TPC vessel has excellent radiopurity, thus shielding the active xenon volume from outside gamma rays without adding significant contaminations. Still, HFE is expensive and adds complexity to the detector's engineering. This study uses GEANT4 simulations to estimate background effects in the active xenon from a varying HFE thickness, in an effort to simultaneously minimize backgrounds and HFE volume. We have determined that a minimum HFE thickness of slightly more than 0.75 m will reduce counts from external sources in a $\sim$52 keV energy range about the 0$\nu \beta \beta $ Q-value to less than 1 per year, while additional HFE will have diminishing impacts. This finding informs required HFE quantities, cryostat design specifications, and permissible radiopurity levels of experiment components outside the HFE barrier. [Preview Abstract] |
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EA.00077: Sensitivity of large-scale neutrino detector to 40K geoneutrinos Yocheved Ungar Uranium, Thorium and Potassium are the primary radioactive constituents of Earth's mantle and crust. Neutrinos released during the decay of these radioactive elements can be used to directly study the bulk composition of Earth's interior. While existing detectors such as a KamLand and Borexino have detected $^{232}$Th and $^{238}$U, they do not have the sensitivity to observe the low energy ($<$1.8 MeV) $^{40}$K geoneutrinos. $^{40}$K geoneutrinos have been predicted to be the most abundant of the radioactive elements in Earth's interior and therefore are of particular interest. I am studying the feasibility of using a large scale (1000 ton) scintillator based detector to search for $^{40}$K geoneutrinos that interact with the scintillator through the process of antineutrino-electron scattering. I will present the results of calculations of neutrino flux predictions and the expected number of scattering events in a kiloton-scale detector as well as studies of backgrounds and their effect on the viability of detecting $^{40}$K geoneutrinos. [Preview Abstract] |
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EA.00078: Analysis of Nuclear Reactor Background Radiation for Neutrino Experiments Ricky Leblanc, J.C. Blackmon, B.C. Rasco, H.P. Mumm Prior measurements of reactor antineutrinos have found a lower flux than expected. Precision measurements of antineutrino energy spectra are important for understanding the anomaly, reactor safeguards, and nuclear nonproliferation. Antineutrino detector designs rely on good characterization of gamma-ray and neutron backgrounds near the reactor core. To study the gamma-ray background at the NIST research reactor, spectra were collected using a 6.25 cm diameter x 5.5 cm germanium detector. We analyzed the measured spectra using simulations of the detector response using the GEANT4 toolkit to determine background fluxes and build a background model that will be used to understand shielding requirements and the impact of backgrounds on potential short-baseline reactor antineutrino studies at NIST. [Preview Abstract] |
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EA.00079: Development and Testing of an Improved Active Gas Target Design for ANASEN Alexandra LeViness, J.C. Blackmon, C.M. Deibel, E. Good, A.A. Hood, K.C. Joerres, R.T. Leblanc, K.T. Macon, B.C. Rasco, L. Baby, I. Wiedenhover The Array for Nuclear Astrophysics and Structure with Exotic Nuclei (ANASEN) is a charged particle detector array with an active gas target-detector capability for direct measurements of nuclear reactions, which are important in stellar explosions, involving radioactive ions. We have developed a modified active gas target design for ANASEN that both improves the resolution for detection of light ions and includes a new capability for coincident heavy ion detection to improve selectivity. Improvements also include the addition of state-of-the-art fast digital electronics. The performance of the new active gas detector was characterized using measurements with an alpha source and silicon strip detector. We will present the new design and results from performance studies as a function of gas composition and operating voltage. [Preview Abstract] |
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EA.00080: Exact Solutions for Pairing Correlations Among Protons and Neutrons Madeleine Miora, Kristina Launey, David Kekejian, Feng Pan, Jerry Draayer Using the nuclear shell model we are able to achieve, for the first time, exact solutions for pairing correlations for light to medium-mass nuclei, including the challenging proton-neutron pairs, while also identifying the primary physics involved. We utilize a new Hamiltonian with only two adjustable parameters. In addition to a single-particle energy term and the Coulomb potential, the shell-model Hamiltonian consists of isovector T=1 pairing interaction and average proton-neutron isoscalar T=0 interaction. The T=0 term describes the average interaction between non-paired protons and neutrons. This Hamiltonian is exactly solvable, but calculations represent a challenge, as they require highly non-linear equations to be computed. With this model, including from 3 to 7 single-particle energy levels, we can reproduce experimental data for 0 + state energies for isotopes with mass A=10 through A=62 exceptionally well including isotopes from He to Ge. These results provide a further understanding for the key role of proton-neutron pairing correlations in nuclei, which is especially important for waiting-point nuclei on the rp-path of nucleosynthesis. [Preview Abstract] |
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EA.00081: Feasibility Study of Polarized Proton Beams at Fermilab Callum Aldred, Wolfgang Lorenzon The feasibility of establishing a polarized proton beam in the Fermilab Main Injector accelerator complex is being investigated. Availability of a high luminosity polarized beam would enable measurements of polarized Drell-Yan production of di-muon pairs with hydrogen, deuterium and nuclear targets far more precise than at any other laboratory around the world. Due to spin-depolarizing resonances, a Siberian Snake is required in the Main Injector to maintain high beam polarization. Spin-tracking simulations must be performed to ensure the snake's effectiveness as the beam crosses many depolarizing resonances which become stronger as the beam energy increases. Using a lattice of the magnetic elements and the accelerator simulation software ``zgoubi,'' protons of varying emittance levels and momentum spreads were tracked through the acceleration of the beam from 8.9 GeV to 120 GeV. Results of the spin tracking simulations in the Main Injector will be presented and future plans that include the entire accelerator complex will be discussed. [Preview Abstract] |
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EA.00082: Development of a Liquefied Noble Gas Time Projection Chamber Ezra Lesser, Aaron White, Christine Aidala Liquefied noble gas detectors have been used for various applications in recent years for detecting neutrinos, neutrons, photons, and potentially dark matter. The University of Michigan is developing a detector with liquid argon to produce scintillation light and ionization electrons. Our data collection method will allow high-resolution energy measurement and spatial reconstruction of detected particles by using multi-pixel silicon photomultipliers (SiPM) and a cylindrical time projection chamber (TPC) with a multi-wire endplate. We have already designed a liquid argon condenser and purification unit surrounded by an insulating vacuum, constructed circuitry for temperature and pressure sensors, and created software to obtain high-accuracy sensor readouts. The status of detector development will be presented. [Preview Abstract] |
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EA.00083: Upgrading KamLAND-Zen for improved sensitivity to neutrinoless double-beta decay Emmett Krupczak KamLAND is a 1 kton liquid scintillator antineutrino detector located underground in Kamioka, Japan. The KamLAND-Zen experiment began in 2011, using KamLAND to search for neutrinoless double-beta decay ($0\nu\beta\beta$). This process, if observed, would indicate that neutrinos are their own antiparticle and thus are Majorana fermions, a discovery that could help explain the matter-antimatter discrepancy in our universe. Currently, KamLAND-Zen is one of the most sensitive experiments to $0\nu\beta\beta$. In order to improve upon the present limits for $0\nu\beta\beta$, KamLAND is undergoing a series of upgrades to reduce background. This includes the construction of a new inner nylon chamber (``mini-balloon''). The current results and design considerations for the mini-balloon will be discussed. [Preview Abstract] |
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EA.00084: NuDot: Search for neutrinoless double-beta decay Jesse Santana NuDot is a prototype, liquid scintillator detector, to demonstrate that the separation of directional Cherenkov light from isotropic scintillation light is possible using sub-nanosecond photodetectors. NuDot is currently being tested on a small scale before ramping up to a one-metric ton prototype in the next three years. A proof-of-concept setup for separating the light as well as calibrating the PMTs’ timing has been designed. The setup consist of two LEDs, the first of which will mimic the cherenkov light while the second represents the scintillating light. NuDot's main application is the search for neutrinoless double beta decay, but it could also be used to reduce backgrounds in studies of geo-neutrinos, solar neutrinos, supernovae neutrinos and neutrino interactions. By being sensitive to the Cherenkov light a detector will have directionality for events and increase it’s energy resolution- these two effects can provide methods to veto backgrounds- which then allow for a better analysis of rare phenomena such as neutrinoless double beta decay. [Preview Abstract] |
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EA.00085: Pion loop contribution to the nucleon self-energy interpolated between the instant form and the front form of relativistic dynamics Colton Bradley, Chueng-Ryong Ji The equivalence of the light-front, equal-time and covariant formulations in meson-baryon interactions has been previously demonstrated. In particular, the self-energy of a nucleon dressed by pion loops with the pseudovector $\pi NN$ coupling has been discussed to show the universality of the leading nonanalytic behavior of the chiral dynamics consistent with QCD. In this poster, we present the link between the instant form dynamics and the light-front dynamics by interpolating them together with an interpolation variable. We confirm the universality of the leading nonanalytic behavior of the chiral dynamics by verifying the independence of this behavior from the interpolation variable. [Preview Abstract] |
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EA.00086: Nuclear reaction rates and their influence on nucleosynthesis in the neutrino-p-process Daniel Hatcher, Carla Frohlich, Georgios Perdikakis The synthesis of elements heavier than iron in the early stages of galactic evolution is commonly attributed to Type II (core collapse) supernova explosions. However, the currently accepted mechanisms of heavy element synthesis through neutron capture processes (r-process and s-process) cannot explain the abundance patterns seen in very old galactic halo stars. A proposed solution to this problem is the neutrino-p-process, which takes place in the strong neutrino winds of core-collapse supernovae. In the neutrino-p-process, antineutrinos absorbed by protons yield neutrons that are quickly captured by the surrounding, proton-rich nuclei through (n,p) reactions. Such interactions allow for the nucleosynthesis of elements with atomic mass numbers greater than 64 (this includes Sr, Y, Zr and others possibly up to Sn). We study the sensitivity of the $\nu $p-process abundance pattern to (n,p), (p,$\gamma$), and (n,$\gamma$) rates for nuclei between Ni and Sn. We illustrate our findings for three different initial electron fractions and two representative trajectories. We discuss how these rates influence the abundance pattern and the nuclear flow. We observe the effects of predicted reaction rates on the abundance pattern and nuclear flow. [Preview Abstract] |
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EA.00087: Vernier Scan Analysis for PHENIX Run 15 p+p Collisions, $\sqrt{s}$ = 200 GeV Gregory Ottino In high energy nuclear physics, cross-section measurements are critical to form an understanding of particle production and they require a characterization of absolute integrated luminosity. The technique used by the PHENIX experiment for luminosity calculations is the Vernier Scan or Van Der Meer Scan. The scan consists of sweeping one beam across the other in the vertical and radial directions in the transverse plane, and then fitting the data of event rate vs. position to a 2D Gaussian distribution. The fit is analyzed to extract the overlap profile of the colliding bunches. The extracted widths, along with the number of protons, are used to calculate the luminosity, $\mathcal{L} $. This, in turn, is used to calculate the p+p cross-section available to the minimum bias trigger, $\sigma_{BBC}$. Further analyses provide various correction factors that refine the measurements of rates and positions, improving the initial calculations of $\mathcal{L}$. Final corrected measurement of $\sigma_{BBC}$ is used to calculate integrated luminosity in any of the cross-section measurements with the relevant PHENIX data set. The current data set to be analyzed is from PHENIX Run 15 p+p collisions at $\sqrt{s} = 200$ GeV. [Preview Abstract] |
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EA.00088: Investigating TwinSol Gas Cell Windows Kimmy Cushman In order to study reactions with unstable nuclei, radioactive-ion beams must be used. One method for producing radioactive beams is the TwinSol experimental setup at the University of Notre Dame. At TwinSol, stable and unstable isotope beams bombard a gas target, where one atmosphere of gas must be confined from the surrounding vacuum. Thin foil windows are used to contain the gas in the cell. In order to optimize the quality of secondary beams from TwinSol, it is necessary to understand and minimize the effects of energy loss and straggling in the windows. We have investigated five different materials to test the strength and durability under typical TwinSol beam conditions. Preliminary results indicate that two of the materials are potential candidates for future TwinSol experiments. We have calculated the beam scattering, stopping powers and equilibrium foil window temperatures, which will help in determining the metrics needed to compare outcomes in future experiments. This work is the beginning of a process to improve the TwinSol design so that secondary beams produced with heavier ions such as Oxygen, Fluorine, and Neon can be pursued. [Preview Abstract] |
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EA.00089: From beta-stability to neutron drip-line: a study of radiative neutron capture for the even-even nuclei Abdellatif Dablouk Radiative neutron capture cross-sections for even-even nuclei from beta-stability to the neutron drip-line (as per the FRDM) are presented. In the theoretical study, the cross-sections are calculated using the CIGAR statistical model code in conjunction with a core-coupling code that accounts for the direct capture component in the radiative capture process. These neutron capture cross-sections are more suitable for nucleosynthesis studies modeling the abundances of nuclei after the r-process freeze-out. The abundances extracted from this project help elucidate some of the nuclear structure and nuclear physics that pertain to, specifically, neutron-rich nuclei and, more generally, the r-process as a whole. [Preview Abstract] |
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EA.00090: Analyzing the Structure of 14O with TwinSol and AT-TPC Louis Jensen Nuclei are known to exhibit clustering, a phenomenon in which the structure of the nucleus forms clusters resembling alpha particles. Understanding the origins of alpha clusterization is an important aspect of nuclear structure and the formation of light elements in astrophysical environments. One of the places in which these cluster structures have been found is in the 14C nucleus. Due to isospin symmetry, the symmetry between a proton and neutron with respect to the nuclear force, we expect cluster structures to exist in 14C's mirror nucleus, 14O. In order to look for cluster states in 14O, we will use resonant scattering of a 10C beam with a 4He target. The first step wasto study the viability of producing a radioactive 10C beam using a 10B $+$ 3He reaction. The 10C beam will separated from other reaction products using a pair of superconducting solenoid magnets called TwinSol. The production yields of 10C have been measured using a beta-decay detector and silicon gamma detector. By fitting the beta and gamma decay data, we have been able to analyze the reactions yields of the 10B $+$ 3He reaction and determined this to be a viable reaction to create a 10C beam. Now we will implant our 10C beam onto a 4He active-target in a time projection chamber. The time projection chamber will allow us to measure the paths and times of the reactions in the 4He gas chamber. Using this data, we will study the properties and structures of the 14O nucleus. [Preview Abstract] |
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EA.00091: Comparison of Optical Models for 400 MeV alpha scattering off $^{90}$Zr and $^{92}$Mo Daniel Jones, Kevin Howard, Umesh Garg, Menekse Senyigit Nuclear incompressibility is an important parameter governing the equation of state of nuclear matter. From the measurable centroid energies of the Isoscalar Giant Monopole Resonance (ISGMR), the incompressibility of nuclear matter can be calculated. The first necessary step is to fit elastic scattering angular distributions for a particular reaction and test the obtained model dependent parameters by calculating low-lying discrete state distributions for target nuclei. This study tests the suitability of two optical models to reproduce the angular distributions of differential cross sections from elastic and inelastic scattering of 400-MeV alpha particles. The first model utilizes a single folded potential for both the real and imaginary volume terms, and the second utilizes a single folded potential for the real volume term, and a phenomenological Woods-Saxon potential for the imaginary volume term. The elastic distributions for two heavy isotopes, $^{90}$Zr and $^{92}$Mo, are analyzed and the best parameter sets for each are shown. From this comparison, it is concluded that the second model, the so called ``hybrid model,'' is better able to reproduce the angular distributions for both $^{90}$Zr and $^{92}$Mo. Future work will include the Multipole Decomposition Analysis (MDA) for each reaction. [Preview Abstract] |
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EA.00092: Designing an Active Target Test Projection Chamber James Koci The development of instrumentation in nuclear physics is crucial for advancing our ability to measure the properties of exotic nuclei. One limitation of the use of exotic nuclei in experiment is their very low production intensities. Recently, detectors, called active-target dectectors, have been developed to address this issue. Active-target detectors use a gas medium to image charged-particle tracks that are emitted in nuclear reactions. Last semester, I designed a vacuum chamber to be used in developing Micro-Pattern Gas detectors that will upgrade the capabilities of an active-target detector called the Prototype AT-TPC. With the exterior of the chamber complete, I have now been using an electric field modeling program, Garfield, developed by CERN to design a field cage to be placed within the vacuum chamber. The field cage will be a box-like apparatus consisting of two parallel metal plates connected with a resistor chain and attached to wires wrapped between them. The cage will provide a uniform electric field within the chamber to drift electrons from nuclear reactions down to the detector in the bottom of the chamber. These signals are then amplified by a proportional counter, and the data is sent to a computer. For the long term, we would like to incorporate a Micro-Pattern Gas Detectors in the interior of the chamber and eventually use the AT-TPC to examine various nuclei. [Preview Abstract] |
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EA.00093: ICoN, the Interactive Chart of Nuclides Kevin Lee, Matthew Mumpower, Ani Aprihamian Nuclear data is critical to research fields from medicine to astrophysics. The chart of nuclides is a more descriptive version of the periodic table that can be used to visualize nuclear properties such as half-lives and mass. We have created ICoN (simply short for Interactive Chart of Nuclides), an API which can be used to visualize theoretical and experimental datasets. This visualization is achieved by using D3 (Data Driven Documents), HTML, and CSS3 to plot the elements and color them accordingly. ICoN features many customization options that users can access that are dynamically applied to the chart without reloading the page. Users can save the customized chart they create to various formats. We have constructed these features in order to provide a unique approach for researchers to interface with nuclear data. ICoN can also be used on all electronic devices without loss of support. We report on the current progress of this project and will present a working demo that highlights each aspect of the aforementioned features. This is the first time that all available technologies are put to use to make nuclear data more accessible than ever before. This is a first and we will make it available as open source ware. [Preview Abstract] |
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EA.00094: Testing the predictive power of statistical model calculations of the (a,g) reaction cross-sections for the p-process Brendan Murphy, Anna Simon \textit{p}-process nucleosynthesis is believed to be the origin of 35 stable, proton-rich nuclei called ``p-nuclei'', that cannot be synthesized by neutron captures. The complex \textit{p}-process network includes, among others, ($\alpha,\gamma$) reactions, whose cross-sections are not very well described by current theoretical models. Here, a collection of experimentally measured ($\alpha,\gamma$) reactions from the KADoNiS-p database was used as a test for various models obtained from TALYS, a nuclear reaction program, and NON-SMOKER, the principal theoretical database in this field. Statistical models in this investigation required the alpha optical model potential (aOMP), the gamma strength function (gSF), and the level density model (ld) as input. Permutations of all three were used in theoretical calculations; as there exist 5 separate models for aOMP and gSF, and 6 for ld, there were 150 combinations of interest. After calculating cross-sections with these parameters, a $\chi^{2}$ test was used to determine the set of permutes that was closest to the experimental data. The ($\alpha,\gamma$) reaction of the \textsuperscript{91}Zr target is presented as the example case. [Preview Abstract] |
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EA.00095: Examining the Structure of the Oxygen-16 Nucleus Ethan Sauer, Ani Aprahamian, Wanpeng Tan, Armen Gyurjinyan, Bryce Frentz, Benjamin Guerin The intent of this work is to explore the structure of the nucleus of Oxygen-16 (16O), which consists of four alpha particles, each with two protons and two neutrons. 16O is generated via the fusion of helium and carbon during stellar nucleosynthesis. This reaction is crucial to the existence of life. By measuring the structure of the 16O nucleus, we hope to gain a better understanding of stellar evolution and processes. The theoretical state of most interest is a linear arrangement of the four alpha particles, proposed by Chevallier et al. in their 1967 paper to explain the surprisingly large moment of inertia of the nucleus they measured. [1] The existence of this state can be most accurately observed through an analysis of the energy spectra of the decay products. This method has previously been implemented at Notre Dame by Freer et al. when a similar structure, that of Carbon-12 (12C), was analyzed, and a previously unknown state was observed. [2] The data gathered is analyzed using the method of angular correlation, which makes use of the angles and energies of decay products relative to the center of mass frame to reconstruct possible spins of the initial state. Analysis is currently underway and results will be presented at CEU 2015. \\[4pt] [1] P. Chevallier et al. Physical Review Vol. 160, No. 4 (August 1967), p. 827.\\[0pt] [2] M. Freer et al. Physical Review C 83 (March 2011), p. 034314. [Preview Abstract] |
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EA.00096: COSY Simulations to Guide Commissioning of the St. George Recoil Mass Separator Jaclyn Schmitt, Michael Moran, Christopher Seymour, Gwenaelle Gilardy, Zach Meisel, Manoel Couder The goal of St. George (STrong Gradient Electromagnetic Online Recoil separator for capture Gamma ray Experiments) is to measure ($\alpha $,$\gamma )$ cross sections relevant to stellar helium burning. Recoil separators such as St. George are able to more closely approach the low astrophysical energies of interest because they collect reaction recoils rather than $\gamma $-rays, and thus are not limited by room background. In order to obtain an accurate cross section measurement, a recoil separator must be able to collect all recoils over their full range of expected energy and angular spread. The energy acceptance of St. George is currently being measured, and the angular acceptance will be measured soon. Here we present the results of COSY ion optics simulations and magnetic field analyses which were performed to help guide the commissioning measurements and diagnostic upgrades required to complete those measurements. [Preview Abstract] |
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EA.00097: A generalized framework for nucleosynthesis calculations Trevor Sprouse, Matthew Mumpower, Rebecca Surman, Ani Aprahamian Simulating the astrophysical synthesis of elements is a difficult process requiring a detailed pairing of knowledge from both astrophysics and nuclear physics. Astrophysics guides the thermodynamic evolution of an astrophysical event. We present Portable Routines for Integrated nucleoSynthesis Modeling (PRISM), a nucleosynthesis framework written in Fortran that combines as inputs a thermodynamic evolution and nuclear data to time evolve the abundances of nuclear species. PRISM implements an algorithm we have developed that allows it to include any nuclear reaction in its calculations, including fission reactions with probabilistically distributed daughter products. Furthermore, because these calculations are often very complicated, PRISM dynamically optimizes itself based on the conditions at each time step in order to greatly minimize total computation time. This approach enables PRISM to quickly and accurately model nucleosynthesis in a broad range of astrophysical events. We highlight PRISM's effectiveness by demonstrating its use to model r-process nucleosynthesis, with nuclear fission among the reactions included in its calculations. [Preview Abstract] |
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EA.00098: Production of Unbound Resonance in 23O Jaclyn Brett, Paul DeYoung, Ali Rabeh, Matthew Tuttle-Timm, Nathan Frank, Michael Jones, Michael Thoennessen The nuclear structure of a state in a given isotope is determined by which nucleons occupy the bound and unbound energy levels. This state determines the energy of decay, which can be calculated from the energy and momentum of the fragment and neutron. From the calculated decay energy, information about an isotope's nuclear structure can be found. At a National Superconducting Cyclotron Laboratory experiment, a 101.3 MeV/u 27Ne ion beam hit a liquid deuterium target, causing reactions which produced several isotopes. Many of these isotopes decayed, resulting in a~charged~fragment and~one or more neutrons. A superconducting dipole magnet bent the path of the fragments into a series of charged-particle detectors. Neutrons from these decays were measured as they interacted with arrays of scintillating plastic bars. One of the isotopes produced was 22O, most likely formed in two ways in this experiment. Either $\alpha $-stripping of the 27Ne beam resulted in 23O, which decayed into 22O $+$ n or 2-proton stripping of the 27Ne beam resulted in 25O, which decayed into 22O $+$ 3n. The cross-sections and the nature of decay for both of these processes will be determined. In addition, resonances of other unbound nuclear systems may also be included for cross-section production comparisons. [Preview Abstract] |
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EA.00099: Computational Model of Fluorine-20 Experiment Thomas Chuna, Paul Voytas, Elizabeth George, Oscar Naviliat-Cuncic, Alexandra Gade, Max Hughes, Xueying Huyan, Sean Liddick, Kei Minamisono, Dirk Weisshaar, Stanley Paulauskas, Gilles Ban, Xavier Flechard, Etienne Lienard The Conserved Vector Current (CVC) hypothesis of the standard model of the electroweak interaction predicts there is a contribution to the shape of the spectrum in the beta-minus decay of $^{20}$F related to a property of the analogous gamma decay of excited $^{20}$Ne. To provide a strong test of the CVC hypothesis, a precise measurement of the $^{20}$F beta decay spectrum will be taken at the National Superconducting Cyclotron Laboratory. This measurement uses unconventional measurement techniques in that $^{20}$F will be implanted directly into a scintillator. As the emitted electrons interact with the detector material, bremsstrahlung interactions occur and the escape of the resultant photons will distort the measured spectrum. Thus, a Monte Carlo simulation has been constructed using EGSnrc radiation transport software. This computational model’s intended use is to quantify and correct for distortion in the observed beta spectrum due, primarily, to the aforementioned bremsstrahlung. The focus of this presentation is twofold: the analysis of the computational model itself and the results produced by the model. [Preview Abstract] |
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EA.00100: Testing Monte Carlo Simulations for Neutron Scattering in MoNA A. Hamann, S. Garrett, T. Seagren, N.E. Taylor, W.F. Rogers Monte Carlo simulations provide an important tool for nuclear physics research, both in preparing for experiments, and in interpreting experimental data. The Modular Neutron Array (MoNA) and the Large area multi-Institutional Scintillator Array (LISA) are used in conjunction with the Sweeper Magnet and charged particle detector chamber at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University to study the properties of exotic, neutron-rich nuclei. We use simulations to model our BC408 scintillator detectors and extract physics results from experimental data. We have developed specific simulations in preparation for an experiment we will conduct at the Los Alamos Neutron Science Center (LANSCE), where we will direct a well-defined neutron beam onto a cluster of 16 MoNA detector bars and observe the scattering patterns of single neutrons. Simulations enable us to study the predicted light output generated by individual neutron scattering channels from Carbon and Hydrogen. The data we will generate in the LANSCE experiment will provide a large experimental database with which to test the reliability of our simulations. This is important since our understanding of nuclei far from stability is becoming increasingly reliant on simulations. [Preview Abstract] |
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EA.00101: Simulations for a new detector of low-energy beta delayed protons at NSCL Madison Harris, David Perez-Loureiro, Christopher Wrede Our current understanding of astrophysical phenomena such as classical novae is limited by uncertainties in certain key nuclear reaction rates. Of particular interest is the reaction rate of $^{30}$P(p,$\gamma )^{31}$S, which is a potential nucleosynthesis bottleneck in classical novae. In order to reduce the uncertainty in that and other key reaction rates, a new micro pattern gas amplifier detector will be built at the National Superconducting Cyclotron Laboratory on the campus of Michigan State University. Through the detection of beta delayed proton emission from $^{31}$Cl in the new detector, we will be able to measure the proton branching ratios of $^{31}$S resonances providing a key component of the $^{30}$P(p,$\gamma)^{31}$S resonance strengths. To aid in the design of the detector, simulations using the Geant4 Proton Detector simulation have been run to determine the behavior of protons in a variety of gases, under different pressures, and with protons of different energies. More specifically, we have looked at the energy deposition of protons as a function of position in the detector in order examine how various pad geometries will affect efficiency, pad multiplicity, and the beta background. [Preview Abstract] |
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EA.00102: Neutron unbound resonances cataloged by isotope and invariant mass measurements for nuclei Z$=$1-12 Elizabeth Havens, Joseph Finck, Paul Gueye, Michael Thoennessen Prior to 2014, no comprehensive study had been undertaken to compile experimental results from neutron unbound spectroscopy using invariant mass measurements, gamma resolutions and half-lives. Through the collaborative efforts of Central Michigan University, Hampton University and the NSCL, a project was initiated to catalog all unbound resonances in light nuclei (Z$=$1-12). Unbound resonances were characterized by having a confirmed neutron decay branch and/or an energy level greater than the neutron binding energy listed for that isotope, according to either the NNDC's ENSDF or XUNDL and the referred journals therein. This was initially compiled in July 2014 and presented in October of that year. Recent discoveries and updates to NNDC have added ten isotopes and their resonances. Additionally, various corrections to previously compiled resonances have been made and equivalent evaluated and unevaluated invariant mass measurements have been consolidated into single entries. The neutron separation energy is noted for each isotope. The isotopes in which unbound resonances occur have been identified and, if known, each unbound resonance's gamma resolution, half-life, method of production and journal reference were also determined. [Preview Abstract] |
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EA.00103: Hyperfine Structure measurements of $^{45}$Sc K.D. Jones, D.M. Rossi, K. Minamisono, A.J. Miller, H. Asberry, P.F. Mantica A chain of charge radii shows discontinuity at nucleon magic numbers. This signature of the shell closure, however, is missing at the neutron magic number $N = 20$ for Ar, Ca and K isotopes. A collinear laser spectroscopy experiment on the stable $^{45}$Sc isotope, which is one proton added to Ca, was performed as a prerequisite of radioactive beam experiments on Sc across $N = 20$ to further investigate the abnormal behavior. The experiment was performed at BEam COoling and LAser spectroscopy (BECOLA) facility at NSCL and a hyperfine spectrum was measured for the electronic transition of $3d4s$ $^3$D$_1 \rightarrow 3d4p$ $^3$F$_2$ at $\lambda = 364.3$ nm in $^{45}$ScII. The magnetic dipole and electric quadrupole hyperfine coupling constants A and B of both the lower and upper states were obtained from the hyperfine structure by fitting a pseudo-Voigt profile. The results obtained from these data are in good agreement with previous values and have smaller statistical errors. The detail of experiment and analysis will be discussed. [Preview Abstract] |
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EA.00104: Population of $^{13}$Be with a Nucleon-Exchange Reaction Bradon Marks, Paul DeYoung, Jenna Smith, Michael Thoennessen Neutron-unbound nuclei are traditionally formed by the removal of one or more nucleons from a fast beam of ions. This method often results in a background, which is difficult to separate from the particle of interest. Nucleon-removal entrance-channels also require the ion beam to be more massive than the particle of interest, which presents the additional challenges of the beam being difficult to make. The present work was done with a nucleon-exchange entrance channel. At the National Superconducting Cyclotron Laboratory, a 71 MeV/u $^{13}$B beam impinged on a 47 mg/cm$^{2}$ thick target of $^{9}$Be. As a result numerous reactions occurred, including the population of $^{13}$Be through the nucleon-exchange entrance-channel. The $^{13}$Be nuclei decayed to $^{12}$Be and one neutron in approximately 10$^{-21}$ seconds. The resulting neutrons were detected by either the Modular Neutron Array (MoNA) or the Large multi-Institution Scintillator Array (LISA), while the $^{12}$Be nuclei were directed through an array of charged particle detectors by a 4T superconducting sweeper magnet. The four-momentum vectors of the fragment nucleus and the neutron were calculated to determine the decay energy of $^{13}$Be. Monte-Carlo simulations consistent with results from previous analyses of $^{\mathrm{13}}$Be were satisfactorily fit to the decay-energy spectrum. Additionally, the cross-section for the nucleon-exchange entrance-channel is consistent with a theoretical prediction. [Preview Abstract] |
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EA.00105: Calibrations for studies of neutron-rich precursor fragments Maria Mazza, Rachel Parkhurst, Samuel Wilensky, Michelle Mosby, Sharon Stephenson, Warren Rogers Heavy ion collisions at relativistic energies produce the radioactive beams used at nuclear structure facilities worldwide. However, there are still unanswered questions about the reaction mechanism of projectile fragmentation and the specific roles that ablation, evaporation, and abrasion play. Using the projectile fragmentation of a $^{32}$Mg beam at 86 MeV/u on a natural Beryllium target at the National Superconducting Cyclotron Laboratory (NSCL), our experimental goal is to better understand the excitation energy and the momentum distribution of the precursors of the observed final fragments (neon, sodium, and fluorine). A suite of charged particle detectors in conjunction with the Modular Neutron Array (MoNA) allows us to analyze both the charged final fragments as well as the coincident neutrons. Detector calibration results and preliminary results will be presented. [Preview Abstract] |
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EA.00106: Real-time Optimization of an Ion Optical Beamline Zachary Schillaci, Matthew Amthor, Dave Morrissey, Mauricio Portillo, Stefan Schwarz, Mathias Steiner, Chandana Sumithrarachchi We have developed an experimental approach to automatically adjust multiple electrostatic and/or magnetic elements on an ion optical beamline, while analyzing the profile of the beam on a detector at the image point, until an optimal tune is found. This approach dramatically simplifies beamline tuning, thus allowing more efficient use of experimental equipment; ensures a more optimal tune is found, providing a more focused beam spot without a significant loss of beam transmission; and will allow the development of specialized optical tunes based on the needs of any given experiment. The approach was tested directly on the D-Line at the National Superconducting Cyclotron Laboratory at Michigan State University in several real-time optimization runs. The initial experiments demonstrate the ability of the optimizer to focus the beam while preserving transmission, ultimately halving $\sigma_{\mathrm{x}}$ and $\sigma_{\mathrm{y\thinspace }}$of the beam spot within a one-hour optimization run relative to that produced through a manual tweak of a model based tune. With further research we plan to generalize the approach to work on any given beamline, including particularly for higher order tunes of fragment separators. [Preview Abstract] |
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EA.00107: Sensitivity of p-Nuclei to (n,g) Reaction Rates Dustin Scriven, Farheen Naqvi, Artemis Spyrou, Anna Simon, Brad Mayer The astrophysical \emph{p}-process, which is responsible for the creation of the proton-rich \emph{p}-nuclei, is still not well understood. A sensitivity study of \emph{p}-nuclei abundances to (\emph{n,$\gamma$}) and (\emph{$\gamma$,n}) reaction rates was conducted at the National Superconducting Cyclotron Laboratory using a nuclear reaction network created at Clemson University. This network simulates the explosive shock front of a Type II supernova passing through the oxygen/neon layer of a 25 \emph{M$_{\odot}$} star. Reaction rates of many (\emph{n,$\gamma$}) reactions and their inverses were increased and decreased by a factor of 3 and the effects were observed. Probing the sensitivity of \emph{p}-nuclei abundances aids in pointing out reactions important to the \emph{p}-process. In turn, this information can be used as a tool to drive experimental research, helping to decrease uncertainties and increase the robustness of \emph{p}-process and other stellar models. [Preview Abstract] |
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EA.00108: Unbound Resonance of 26F Matthew Tuttle-Timm, Ali Rabeh, Nathan Frank, Jaclyn Brett, Paul DeYoung, Michael Jones, Michael Thoennessen The nuclear structure of a state in a given isotope is determined by which nucleons occupy the bound and unbound energy levels. This state determines the energy of decay, which can be calculated from the energy and momentum of the fragment and neutron. From the calculated decay energy, information about an isotope's nuclear structure can be found. At a National Superconducting Cyclotron Laboratory experiment, a 101.3 MeV/u 27Ne ion beam hit a liquid deuterium target, causing reactions which produced several isotopes. Many of these isotopes decayed, resulting in a charged fragment and one or more neutrons. A superconducting dipole magnet bent the path of the fragments into a series of charged-particle detectors. Neutrons from these decays were measured as they interacted with arrays of scintillating plastic bars. One of the isotopes produced was 26F, formed by 1-proton stripping from the 27Ne beam. This 26F decayed into 25F $+$ n. By calculating the decay energy for this interaction, the first resonant neutron-unbound state in 26F, which has not been significantly observed, will be characterized. In addition, resonances of other unbound nuclear systems may also be included to compare/contrast with these results. [Preview Abstract] |
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EA.00109: Two-particle correlations in 200 GeV p+p with the MPC-EX at RHIC-PHENIX John White The Extension to the Muon Piston Calorimeter (MPC-EX) is a newly installed tungsten-silicon preshower added to enhance the forward (3<|$\eta$|<4) photon identification in $p$$+$$p$ and $p$$+$A collisions in the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC). At these pseudorapidities new and extended measurements using the correlation of two particles can be made. For example, one can look for a flow-like correlation with low momentum pairs in high multiplicity collisions. At higher momentum jet-like correlations probe high-$Q^2$ and low-$x$ partons in the target proton or nucleus and can potentially test models of gluon saturation. In this poster, we outline some details of the MPC-EX detector and its performance in the $p$$+$$p$ and $p$$+$Au runs during 2015 as well as give a current status of two-particle correlation analysis using the MPC-EX. [Preview Abstract] |
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EA.00110: Measurement of Gain and Drift Velocity of the Prototype AT-TPC Michael Wolff, Rim Soussi Tanani, Marco Cortesi, Wolfgang Mittig, Adam Fritsch The Prototype Active-Target Time-Projection Chamber (PAT-TPC) at the National Superconducting Cyclotron Laboratory (NSCL) is used to study reactions induced by radioactive ions in a detector gas that serves both as the target and tracking medium. It employs gaseous amplification of the primary electrons that drift to the amplification gap to track and measure charged particles traversing the active gaseous volume of the chamber. A setup consisting of two THGEMs (Thick Gas Electron Multipliers) stacked on a Micromegas (Micro mesh gas amplifier) device was tested in the PAT-TPC in June and July of 2015. A 337-Si laser, a $^{252}$Cf spontaneous fission source, and an $\alpha$ source were used to ionize target gas molecules in the active volume. Electron drift velocity was measured as a function of the electric field held across the volume and for varying gas compositions ranging from pure H$_2$ to a 95:5 H$_2$:C$_4$H$_{10}$ mixture. Analysis of the tests provided information on conditions for optimal gain for the setup used in an August 2015 PAT-TPC experiment at the University of Notre Dame’s Nuclear Science Laboratory and other future experiments. Data and results will be presented. [Preview Abstract] |
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EA.00111: Extracting the Position from a Silicon Resistive Strip Detector using ~Digital Shaping Algorithms Harrison Sims, Sarah Lonsdale, Andrew Ratkiewicz, Steven Pain, Jolie Cizewski Transfer reactions can be used to study single-particle structure of radioactive nuclei which are important for energy generation and nucleosynthesis in explosive astrophysical environments. The resolution of such measurements performed in inverse kinematics are dependent on the position resolution of the detected ejectile. The Oak Ridge Rutgers University Barrel Array (ORRUBA) of Silicon Resistive Strip Detectors (SRSD) was developed to measure light-ion products from transfer reactions in inverse kinematics with radioactive ion beams. The rise times of signals from resistive detectors are dependent upon the position of the incident charged particle; using analog electronics, the shaping time must be matched to the average response. By using a digital data acquisition system, event-by-event rise time information can be recorded, allowing for better optimized readout of resistive strip detectors. Investigations were made into the effectiveness of different shaping algorithms, such as smoothing filters and derivative filters, on the position resolution. Preliminary results demonstrate that improved position resolution can be obtained from the fast rise slope of the signals. Preliminary results and the first in-beam tests with the Gammasphere ORRUBA Dual Detector for Experimental Structure Studies (GODDESS). [Preview Abstract] |
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EA.00112: The GODDESS ionization chamber: developing robust windows Rose Blanchard, Travis Baugher, Jolie Cizewski, Steven Pain, Andrew Ratkiewicz Reaction studies of nuclei far from stability require high-efficiency arrays of detectors and the ability to identify beam-like particles, especially when the beam is a cocktail beam. The Gammasphere ORRUBA Dual Detectors for Experimental Structure Studies (GODDESS) is made up of the Oak Ridge-Rutgers University Barrel Array (ORRUBA) of silicon detectors for charged particles inside of the gamma-ray detector array Gammasphere. A high-rate ionization chamber is being developed to identify beam-like particles. Consisting of twenty-one alternating anode and cathode grids, the ionization chamber sits downstream of the target chamber and is used to measure the energy loss of recoiling ions. A critical component of the system is a thin and robust mylar window which serves to separate the gas-filled ionization chamber from the vacuum of the target chamber with minimal energy loss. After construction, windows were tested to assure that they would not break below the required pressure, causing harm to the wire grids This presentation will summarize the status of the ionization chamber and the results of the first tests with beams. This work is supported in part by the U.S. Department of Energy and National Science Foundation. [Preview Abstract] |
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EA.00113: Characterization of Bismuth Germanate Detectors for Reaction Studies A. Carls, R.L. Kozub, K.A. Chipps, S.D. Pain, D. Hertz-Kintish, P. Thompson, D. Waddell Nuclear reactions utilizing radioactive ion beams emit particles and electromagnetic radiation that can provide useful information about reaction mechanisms, nuclear structure, and nuclear astrophysics. Owing to their high density and high Z, Bismuth Germanate (BGO) detectors are used in $\gamma$-ray decay studies where high efficiency is required. An array of such detectors will be used for future $\gamma$-ray studies with the new gas jet target JENSA\footnote{K. A. Chipps et al., Nucl. Instr. Meth. Phys. Res. A 763, 553 (2014).} (Jet Experiments in Nuclear Structure and Astrophysics), and the properties of each detector must be well known to better understand the data collected with them. Using the $\gamma$-ray sources $^{137}$Cs and $^{60}$Co along with background radiation, several BGO detectors were characterized by measuring their resolutions and efficiencies as functions of distance between source and detector. A detailed description of the procedure and results will be presented. This work is supported in part by the U.S. Department of Energy and the National Science Foundation. [Preview Abstract] |
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EA.00114: Preamp Testing for GODDESS A. Engelhardt, R.L. Kozub, S.D. Pain, A. Ratkiewicz In nucleon transfer reactions, measurement of charged ejectiles alone is often inadequate for resolving closely spaced energy levels. However, by detecting $\gamma$ rays in coincidence with identified light ejectiles and heavy recoils, energies and angular distributions can be measured for individual final states. The Gammasphere ORRUBA Dual Detectors for Experimental Structure Studies (GODDESS)\footnote{A. Ratkiewicz et al., AIP Conf. Proc. 1525, 487-491 (2013) and references therein.} is designed for this purpose. The ORRUBA silicon strip detector array is used for the charged-particle measurements and requires 720 working channels and preamp chips to process the signals. The preamps were tested by placing one of the silicon detectors in a vacuum chamber with a $^{244}$Cm source. A preamp box containing 72 channels and chips, located outside the chamber and connected to the detector via vacuum feedthroughs, was used to test both the box's functionality and the quality of the chips. Cooling fans were placed at various positions on the preamp box and testing was performed to determine the configuration of fans that contributed minimal noise and optimal cooling. Details of the testing procedures and results will be presented. Research supported by the U.S. Department of Energy. [Preview Abstract] |
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EA.00115: Characterization of Bias Effects on Sodium Iodide Detectors for Reaction Studies Daniel Hertz-Kintish, Jolie Cizewski, Alex Carls, Kelly Chipps, Steve Pain, Paul Thompson, Deion Waddell Nuclear physics reaction and decay studies with radioactive ion beams need high-efficiency detectors for all radiations, including gamma rays. Sodium iodide crystals are well established as $\gamma$-ray detectors, favored for many years for their high efficiency and relatively low cost. Several thallium-activated sodium iodide detectors have been characterized with $\gamma$-ray sources in order for their properties to be well understood and that they may be properly utilized in future experiments. These detectors could be used in nuclear reaction measurements with radioactive ion beams to measure coincident $\gamma$-rays and light charged particles. My contribution was a careful analysis of the effects of the level of bias on the photomultiplier tubes to show how the efficiency and resolution of these detectors can be optimized by controlling this voltage. An analysis of gain shifts due to temperature variations, the photomultiplier aging process, and the bias was also included. This presentation would summarize the status of the characterization of the NaI detectors. [Preview Abstract] |
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EA.00116: ABSTRACT WITHDRAWN |
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EA.00117: Deuterated Polyethylene Target Production for Inverse Kinematic Transfer Reactions S.C. Shadrick, R.L. Kozub, D. Walter, M. Febbraro, S.D. Pain Inverse kinematic transfer reactions play an important role in the study of nuclear structure far from stability, where the radioactive heavy reactant cannot be used as a target. These reactions can give insights into the production of proton-rich species in nova explosions (rp process) and of heavier, neutron-rich isotopes produced in the r-process, where such unstable isotopes could form and quickly react with neutrons to make even heavier species. In general, deuteron stripping reactions [(d,p), (d,n)] serve to provide the single particle structure needed to understand these nucleosynthesis processes. Such experiments require a target containing deuterium, such as a pure gas jet or a solid compound. In preparation for upcoming experiments using the GODDESS array,\footnote{A. Ratkiewicz et al., AIP Conf. Proc. 1525, 487-491 (2013).} deuterated polyethylene films, (C$_2$D$_4$)$_n$, of thicknesses ranging from .04 - 5 mg/cm$^2$ were created. The method used, while similar to previous approaches, involved a number of extra procedures to make the technique more reliable; these procedures will be presented. This research is supported by the Office of Nuclear Physics in the U.S. Department of Energy. [Preview Abstract] |
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EA.00118: Characterization of Resolution and Efficiency of Sodium Iodide Detectors for Reaction Studies Deion Waddell, Alex Carls, Paul Thompson, Daniel Hertz-Kintish The study of nuclear physics with radioactive ion beams requires the understanding of detectors to be used for measuring all types of radiation. Several thallium-activated sodium iodide (NaI(Tl)) detectors were characterized with gamma-ray sources to better understand their properties so they may be utilized for future experiments. A detailed understanding of the resolution and efficiency of the detectors as a function of distance from the sources to the detector, allow us to optimize the detector placement in an experimental setup. Details of the procedure and results will be presented. Work supported in part by the U.S. Department of Energy and the National Science Foundation. [Preview Abstract] |
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EA.00119: Nab Experiment Ryan Whitehead The Nab experiment proposes to precisely measure the electron-neutrino angular correlation parameter, $\textit{a}$, as well as the Fierz interference term, $\textit{b}$, within the triple differential equation that describes neutron beta decay. The experiment will be performed using the Fundamental Neutron Physics Beamline at the SNA in ORNL, using a new electromagnetic field spectrometer and detector design. The parameter $\textit{a}$, is expected to be measured with an accuracy of $10^{-3}$, and will provide a measurement of $\lambda$, the ratio of axial-vector to vector coupling constants. The measurement of $\textit{b}$ is also the first to be done with neutron decay, and will provide an independent limit on the tensor weak coupling. The experimental method will be presented and prototype analysis algorithms discussed. [Preview Abstract] |
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EA.00120: Determination of Concentrations of Radioactive Nuclides in Soil Samples using Gamma Ray Spectroscopy Arsalan Adil, Joshua Weaver A hyper-pure Germanium detector system was used to determine the contents and concentrations of various nuclides in soil samples collected from different parts of the United States. These include areas in close proximity to nuclear power plants, areas susceptible to nuclear fallout from weapons testing from the pre Comprehensive Nuclear Test Ban Treaty (CTBT) period, and areas vulnerable to fallout from Fukushima from the west coast. The concentrations of naturally occurring nuclides in the $^{238}$U, $^{232}$Th, and $^{40}$K decay chains as well as that of synthetic isotopes of $^{137}$Cs and $^{60}$Co were measured with the aid of Genie-2000 and Radware (gf3m). An efficiency curve was obtained by designing a simulation and compared with standard sources. The research, now in its next stage, aims to do the same in samples from Karachi (Pakistan) which is home to three nuclear power plant projects but has no available baseline radioactivity measurements. [Preview Abstract] |
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EA.00121: Dual Target Design for CLAS12 Omair Alam, Gerard Gilfoyle, Steve Christo An experiment to measure the neutron magnetic form factor ($G^M_n$) is planned for the new CLAS12 detector in Hall B at Jefferson Lab. This form factor will be extracted from the ratio of the quasielastic electron-neutron to electron-proton scattering off a liquid deuterium ($LD_2$) target. A collinear liquid hydrogen ($LH_2$) target will be used to measure efficiencies at the same time as production data is collected from the $LD_2$ target. To test target designs we have simulated CLAS12 and the target geometry. Electron-nucleon events are produced first with the QUasiElastic Event Generator (QUEEG) which models the internal motion of the nucleons in deuterium.$^2$ The results are used as input to the CLAS12 Monte Caro code gemc; a Geant4-based program that simulates the particle’s interactions with each component of CLAS12 including the target material. The dual target geometry has been added to gemc including support structures and cryogenic transport systems. A Perl script was written to define the target materials and geometries. The output of the script is a set of database entries read by gemc at runtime. An initial study of the impact of this dual-target structure revealed limited effects on the electron momentum and angular resolutions. [Preview Abstract] |
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EA.00122: Study of the Neutron Detection Efficiency for the CLAS12 Detector Keegan Sherman, Gerard Gilfoyle One of the central physics goals of Jefferson Lab is to understand how quarks and gluons form nuclei. The 12 GeV upgrade is nearing completion and a new detector, CLAS12, is being built in Hall B. One of the approved experiments will measure the magnetic form factor of the neutron. To make this measurement, we will extract the ratio of electron-neutron (e-n) to electron-proton (e-p) scattering events from deuterium in quasi-elastic kinematics. A major source of systematic uncertainty is the neutron detection efficiency (NDE) of CLAS12. To better understand the NDE we used the Monte Carlo code {\it gemc} to simulate quasi-elastic e-n events like those expected in the experiment. We then analyzed the simulated e-n events by using the measured, scattered electron information to predict the neutron's path. The neutron is detected in CLAS12's electromagnetic calorimeter (EC). If the predicted neutron path intersected the fiducial volume of the EC, then we searched for a hit near that point. The NDE is the ratio of the number of neutrons found in the EC to the number of neutrons predicted to hit the EC. The analysis was done using the newly released CLAS12 reconstruction tools. We observe a rapid rise in the NDE at low neutron momentum and a plateau above 60\%. [Preview Abstract] |
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EA.00123: Investigating QGP through Monte Carlo Jet Event Topology Jennifer Coulter Thrust, an infrared safe, perturbatively calculable event shape variable, has been used to explore the geometry of energy momentum flow in $e^{+}e^{-}$ annihilation. The calculation of thrust, thrust major, and thrust minor is dictated by equations arising from QCD. Current QCD theory in $e^{+}e^{-}$ predicts that thrust could have implications for determinations of the strong coupling constant and branching structure of collisions. In order to extend the work done in $e^{+}e^{-}$ to apply to pp and PbPb collisions, analysis of Monte Carlo simulations was developed to create plots of thrust, thrust major, and thrust minor. Going forward, pp and PbPb thrust values from these simulations will be compared in order to study the effects of quenching and hopefully imply new information about quark-gluon plasma. [Preview Abstract] |
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EA.00124: Monte Carlo Investigation of Quark Gluon Plasma Ian Hunt-Isaak The Quark Gluon Plasma (QGP) is a hot, dense state of matter in which the Quarks and Gluons which make up Hadrons are freed hypothesized to be similar to the conditions of the very early universe. The QGP can be generated via the collision of Heavy Ions, Lead (Pb) for this work, at ultrarelativistc velocities. However in QGP is short lived so it cannot be investigated by external probes. Instead internal probes such as jets are used, jets are sprays of particles from a hard scattering of quarks and gluons. It is expected that Proton-Proton (pp) collisions do not generate a QGP so by comparing jet observable in PbPb and pp collisions, we can gain information about the medium. Through comparison of Monte Carlo simulations to data, information about medium can be deduced. For this work a framework to run {\sc PYTHIA, JEWEL, Q-PYTHIA,} and {\sc PYQUEN} was improved upon. The {\sc JEWEL} generator was then used to investigate the 3-Jet to 2-Jet ratio $R_{32}$, a quantity thus far unstudied in Heavy Ion collisions which shows promise as a way to investigate the medium. [Preview Abstract] |
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EA.00125: Time of flight and the MUSE experiment in the PIM1 Channel at the Paul Sherrer Institute Wan Lin The MUSE experiment~in the PIM1 Channel at the Paul Sherrer Institute~in Villigen, Switzerland, measures scattering of electrons and muons from a liquid hydrogen target. The intent of the experiment is to deduce from the scattering probabilities whether the radius of the proton is the same when determined from the scattering of the two different particle types. An important technique for the experiment is precise timing measurements, using high precision scintillators and a beam Cerenkov counter. We will describe the motivations for the precise timing measurement. We will present results for the timing measurements from prototype experimental detectors. We will also present results from a simulation program, Geant4, that was used to calculate energy loss corrections to the time of flight determined between the beam Cherenkov counter and the scintillator.~ [Preview Abstract] |
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EA.00126: Multiple Scattering in Beam-line Detectors of the MUSE Experiment Heather Garland, Clay Robinette, Steffen Strauch The charge radius of the proton has been obtained precisely from elastic electron-scattering data and spectroscopy of atomic hydrogen. However, a recent experiment using muonic hydrogen, designed for high-precision, presented a charge radius significantly smaller than the accepted value. This discrepancy certainly prompts a discussion of topics ranging from experimental methods to physics beyond the Standard Model. The MUon Scattering Experiment (MUSE) collaboration at the Paul Scherrer Institute, Switzerland, is planning an experiment to measure the charge radius of the proton in elastic scattering of electrons and muons of positive and negative charge off protons. In the layout for the proposed experiment, detectors will be placed in the beam line upstream of a hydrogen target. Using Geant4 simulations, we studied the effect of multiple scattering due to these detectors and determined the fraction of primary particles that hit the target for a muon beam at each beam momentum. Of the studied detectors, a quartz Cherenkov detector caused the largest multiple scattering. Our results will guide further optimization of the detector setup. Supported in parts by the U.S. National Science Foundation: NSF PHY-1205782 [Preview Abstract] |
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EA.00127: The 132Sn giant dipole resonance as a constraint on nuclear matter properties Brandon Roach, Giacomo Bonasera, Shalom Shlomo Nuclear giant resonances provide a sensitive method for constraining the properties of nuclear matter (NM) - many of which have large uncertainties - and thereby improve the nuclear energy-density functional. In this work, self-consistent Hartree-Fock random-phase approximation (HF-RPA) theory was employed to calculate the strength function and energy of the isovector giant dipole resonance (IVGDR) in the doubly-magic $^{132}$Sn nucleus. Several (17) commonly-used Skyrme-type interactions were employed. The correlations between the IVGDR centroid energy and each nuclear matter property were explored, as were correlations between the nuclear matter properties and the $^{132}$Sn neutron skin thickness $r_n - r_p$. Experimental data for the IVGDR centroid energy was used to constrain the symmetry energy density, the symmetry energy, and its first and second derivatives, respectively, of NM. Further investigation, particularly of nuclides far from stability, will be needed to extend the nuclear energy-density functional to the extremes of density and neutron abundance found in neutron stars and astrophysical nucleosynthesis environments. [Preview Abstract] |
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EA.00128: The Dynamic Range of LZ Jun Yin The electronics of the LZ experiment, the 7-ton dark matter detector to be installed at the Sanford Underground Research Facility (SURF), is designed to provide a 70{\%} efficiency for events that produce three photoelectrons in the photomultiplier tubes (PMTs). This corresponds approximately to the lowest energy threshold achievable in such a detector, and drives the noise specifications for the front end. The upper limit of the LZ dynamic range is defined by the electroluminescence (S2) signals. The low-energy channels of the LZ amplifiers provide the dynamic range required for the tritium and krypton calibrations. The high-energy channels provide the dynamic range required to measure the activated Xe lines. S2 signals induced by alpha particles from radon decay will saturate one or more channels of the top PMT array but techniques are being developed to recover the information lost due to saturation. [Preview Abstract] |
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EA.00129: Development of the Focal Plane Detection System for the Future Gas-Filled Separator at the Cyclotron Institute Erin Bertelsen, Dmitriy Mayorov, Charles ``Cody'' Folden III A focal plane detection system is being developed for use with the gas-filled separator previously known as SASSYER (Small Angle Separator System at Yale for Evaporation Residues) that will be installed at the Cyclotron Institute at Texas A{\&}M University. This system will be used to study heavy (Z $\ge $ 90) elements and features two 60x40 strip double-sided silicon detectors (DSSDs) and accompanying multiplexing read-out electronics. The DSSDs cover an area of 120x40 mm$^{2}$ and are read-out by fourteen 16-channel multiplexers (Mesytec MUX-16) that perform the function of a preamplifier, shaper, and leading-edge discriminator in one unit. The multiplexers are controlled by four ``MUX drivers,'' each of which serves as a signal bus for multiple MUX-16 boards. The system allows a single 16-channel ADC to read the combined 200 strips of both DSSDs. A four peak source composed of $^{148}$Gd, $^{239}$Pu, $^{241}$Am, and $^{244}$Cm was used to characterize the performance of the system, with a preliminary energy resolution of $\sim$ 60 keV measured for the $^{241}$Am alphas. This contribution will discuss the work performed in assembly of the test setup, optimization and performance check of the multiplexers, and the preliminary energy and position data collected with the $\alpha $-source. [Preview Abstract] |
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EA.00130: Momentum spectra of bottomonium in heavy-ion collisions Jordan Fox, Xiaojian Du, Ralf Rapp The early universe consisted of a dense nuclear medium that took a short time to expand and form hadrons; this medium is called the quark-gluon plasma (QGP). It is believed that a QGP can be created in URHICs, and that heavy quarks created early in the collision act as a probe of the QGP. We investigate models of producing bottomonium ($b\bar{b} \to Y$) states in URHICs at RHIC and LHC energies in order to describe the regeneration of bottomonia from the QGP as it depends on transverse momentum ($ p_T $). To simulate the evolution of the bottomonium abundance in URHICs, we rely on the results of a kinetic rate equation approach, which describes the number of bottomonia $ N_Y $ as it approaches equilibrium. We first implement a blastwave model to estimate the $ p_T$-spectra of locally thermalized $ \Upsilon^{1S} $ and $ \Upsilon^{2S} $ states, boosted by a flow field. However, since bottomonium is not fully thermalized in the QGP, we employ a quark coalescence model with realistic $ b$-quark spectra in the calculation of its in-medium distributions. Finally, the total nuclear modification factor ($ R_{AA}(p_T) $) is calculated accounting for the interplay of suppression and regeneration mechanisms of bottomonium in URHICs as compared to proton-proton collisions. [Preview Abstract] |
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EA.00131: R-Matrix Analysis of the 13C($\alpha$,n)16O Reaction Arthur Kock, Grigory Rogachev \let\s\textsuperscript The \s{13}C($\alpha$,n)\s{16}O reaction plays a crucial role in the main \emph{s}-process occurring in low-mass thermally-pulsing asymptotic giant branch (TP-AGB) stars, which produces about half of all nuclei heavier than iron. However, direct measurements of this reaction cross section near the Gamow-peak energy are currently not possible due to very small reaction cross sections. Additionally, available cross-section data at higher energy have some inconsistencies, leading to significant uncertainties in low energy extrapolations. A global R-matrix fit was conducted, using all available data for the \s{13}C($\alpha$,n)\s{16}O, \s{13}C($\alpha$,$\alpha$)\s{13}C, and \s{16}O(n,n)\s{16}O reactions. Of particular importance was the inclusion of the fixed ANC for the $1/2$+ state at $6.356$ MeV in \s{17}O, which was measured recently using the sub-Coulomb $\alpha$-transfer reaction, as well as the new \s{13}C+$\alpha$ elastic-scattering data measured in the low-energy region $1.6 - 3.8$ MeV. Important constraining information on various resonances was found, and the uncertainty for the astrophysical \s{13}C($\alpha$,n)\s{16}O reaction rate was dramatically reduced. [Preview Abstract] |
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EA.00132: A PYTHIA Simulation Study of Direct-Photon- and $\pi^{0}$-Triggered Hadron Correlations in p$+$p Collisions at $\surd $s$_{NN\, }=$ 200 GeV in Comparison to STAR Data Christopher Marble Heavy-ion collisions at the Relativistic Heavy Ion Collider (RHIC) have provided evidence for the existence of a new hot and dense state of matter called the Quark-Gluon Plasma (QGP). Proton-proton (p$+$p) collisions provide a baseline measurement in order to understand the properties of the QGP in heavy-ion collisions. Comparisons of jet yields in Au$+$Au collisions to those in p$+$p collisions are done to determine the attenuation of hard-scattered partons in the QGP. In this study, p$+$p collisions are simulated at a center of mass energy $\surd $s$_{NN\, }=$ 200 GeV using the PYTHIA 8.185 event generator. Jets are studied via two-particle azimuthal correlations, with the recoil jet analyzed via charged-hadron yields on the away-side ($\Delta \varphi $ approx. $\pi )$ of a $\pi ^{0}$ or a direct-photon trigger. The away-side charged-hadron per-trigger yields at mid-rapidity (\textbar $\eta $\textbar \textless 1), for transverse momenta p$_{T}^{assoc.}$ \textgreater 1.2 GeV/c, are obtained for $\pi^{0}$ and direct-photon triggers for \textbar $\eta $\textbar \textless 1 and p$_{T}^{trig.}$ \textgreater 8 GeV/c. The fraction of transverse momentum carried by triggered $\pi^{0}$ from its hard-scattered ancestors is studied to understand the energy imbalance between the triggered $\pi^{0}$ and the outgoing parton in p$+$p collisions. PYTHIA simulation results of the away-side charged-hadron yields, for $\pi^{0}$ and direct-photon triggers, are in reasonable agreement with the data collected in p$+$p collisions at the STAR experiment. [Preview Abstract] |
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EA.00133: A Study of the Contribution from Non-Perturbative Effects to Di-jet Yields at Forward Rapidity Anna Poulsen, Zilong Chang, Carl Gagliardi It is well known that the proton's spin is equal to $\hbar$/2, but its internal structure and the spin contributions made by its parton constituents, especially gluons, remain enigmatic. By studying asymmetric di-jets produced in polarized proton-proton collisions at forward rapidity, more information about the spin contribution of the gluon can be attained. Next-to-leading order perturbative QCD calculations indicate that measurements of di-jets at forward rapidity with transverse momenta of 5 and 8 GeV/c can provide valuable information regarding the gluon polarization. However these calculations do not include background contributions from initial state-radiation, underlying events and beam remnants that can create additional particles which appear in the detector as jets. In this study, PYTHIA simulations were used to analyze jets of stable final state hadrons. A simple procedure is found to reject the background. Most of the di-jets that remain can be matched to initial hard scattered partons with momentum fractions x$_{2}$ of the order 10$^{-3}$ and x$_{1}$ of 0.4 or greater. These kinematics indicate that the remaining di-jets will provide relevant information about the gluon's polarization and lead to a better understanding of the proton's structure at the partonic level. [Preview Abstract] |
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EA.00134: Study of Gamow-Teller transitions with J=0 and J$_{max}$ pairing Ricardo Garcia, Larry Zamick Allowed Gamow-Teller transitions are sensitive to the interactions which are used. In this single j shell study, we consider the 2 extremes J=0 pairing and J$_{max}$ pairing as well as ``half.'' Also, for comparison, a realistic interaction, MBZE. For $^{43}$Sc decay J=0 pairing yields a maximum B(GT) for I=7/2 to 7/2 but is zero for 7/2 to 9/2 and 7/2 to 5/2. This is tied to a selection rule that one cannot simultaneously change reduced isospin and seniority. For $^{46}$Ti I=1 to I=0 there is not monotonic behavior as one goes from J$_{max}$ to J=0 pairing, explained by the fact that that there is an isospin crossover of J=1 T=2 as one goes to the J=0 pairing limit. Comparison with experiment is made. [Preview Abstract] |
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EA.00135: Distribution of Ions in Laser-Driven Fusion Reactions MacKenzie Warrens, Matteo Barbarino, Aldo Bonasera, Dario Lattuada Experiments of laser-driven fusion reactions are important for many aspects, such as measuring the cross section of plasma. In the experiments at University of Texas using the Texas Petawatt laser, deuterium clusters of various sizes suspended in $^{\mathrm{3}}$He gas absorb the laser's energy and are irradiated. The clusters undergo a Coulomb explosion, forming a hot plasma which initiates the reactions. This analysis studies two possible fusions: D(d, $^{\mathrm{3}}$He)n and $^{\mathrm{3}}$He(d,p)$^{\mathrm{4}}$He. Signals are recorded using a Faraday cup detector, then transformed and analyzed in energy space. In this work, we investigate if the log-normal distribution is an appropriate description of the energy distribution of the ions. If the log-normal distribution is a good fit, the energy distribution can be thought of as chaotic enough to appear thermalized. The chaos may be due to many-body interactions over long distances, as well as the different charges and masses of the particles involved. Using the well-known S-factor for the two reactions and the extrapolated fits, the number of fusions is calculated and compared with experimental data. [Preview Abstract] |
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EA.00136: Electrical properties of various gas mixtures for active target detector application Daniel Yates, Grigory Rogachev, Evgeniy Koshchiy, Ethan Uberseder, Josh Hooker Experiments with rare isotope beams (RIBs) open new opportunities to study properties of exotic nuclei and measure reaction cross sections relevant for nuclear astrophysics with radioactive ions. However, the low intensity of RIBs requires the development of new, more efficient detectors such as the Texas Active Target (TexAT) detector currently being developed at the Cyclotron Institute. With this detector, the target gas is also used as the active medium for tracking and energy loss measurements of charged recoils. Various gas mixtures will be used under different conditions and it is important that drift velocity and gas gain are well established. This study uses a time projection chamber with an applied electric field to measure drift velocity and electron gains of four gases to be used as targets in TexAT. The experimental values are then compared to simulation. Drift velocities of electrons were measured as a function of the electric field for each gas and pressure and then were compared to simulated values obtained from CERN's Garfield$++$ simulation package. The simulated and experimental drift velocities matched with root-mean-square deviations typically less than 10{\%} ~for each pressure. These results provide important accuracy verification of the simulation programs and determine systematic uncertainties in track reconstructions with TexAT which rely on these simulations. [Preview Abstract] |
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EA.00137: Exploration of similarity renormalization group generators in 1-dimensional potentials Matthias Heinz The Similarity Renormalization Group (SRG) is used in nuclear theory to decouple high- and low-momentum components of potentials to improve convergence and thus reduce the computational requirements of many-body calculations [Phys. Rev. C 75, 061001 (2007)]. The SRG is a series of unitary transformations defined by a differential equation for the Hamiltonian. It includes a matrix called the generator that defines how the transformation will change the Hamiltonian. The commonly used SRG generators evolve the Hamiltonian into a band-diagonal shape. Evolving potentials using SRG induces many-body forces. If these forces are truncated at the N-body level, this systematically introduces errors from omitted (N+1)-body forces when modeling many-body systems. While established generators are fairly successful, alternative generators may converge faster, be faster to calculate, or lead to smaller many-body forces. In particular, recent findings suggest that a block diagonal generator may induce smaller many-body forces [Phys. Rev. C 90, 034302 (2014)]. We use 1-dimensional systems of two, three, and four bosons [Nuclear Physics A 818 (2009) 152-173] as a theoretical laboratory for studying how these alternative generators perform, and to observe how they induce many-body forces. [Preview Abstract] |
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EA.00138: Improved numerical projection of angular momentum Kevin O'Mara, Calvin Johnson Nuclear many-body states have good angular momenta, but many theoretical building blocks such as deformed Slater determinants do not. Hence one must numerically project out states of good angular momenta, usually through a computationally taxing three-dimensional integral. We took an existing code for angular-momentum projected Hartree-Fock\footnote{J. T. Staker and C. W. Johnson, arXiv: 1304.7292} and improved its performance, partly through judicious ordering of the loops, precomputing arrays of important combinatorics, and careful application of parallelization. We also investigated a novel inversion scheme. This work is potentially applicable to multiple approaches in many-body calculations,\footnote{T. Otsuka, et al. Prog. Part. Nucl. Phys. 47, 319 (2001); J. Dobaczewski and P. Olbratowski. Comp. phys. Comm. 167, 214 (2005); J. M. Yao, et al. Phys Rev C 81, 044311 (2010)} and should also be generalizable to particle number projection. [Preview Abstract] |
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EA.00139: Modeling Initial Conditions in Light-Ion Collisions Kevin Welsh, Jordan Singer, Brian Baker When particles collide at relativistic speeds, they generate an exotic form of matter called quark gluon plasma. Currently, the only way to observe this type of matter in nuclear collisions is at particle accelerators, such as the Relativistic Heavy Ion Collider. The relative initial position and orientation of the colliding nuclei has a large influence on the anisotropies found in the plasma that evolves from it, and the initial orientation depends on everything from the energy of the nuclei to the internal structure of their nucleons, and there are aspects of the plasma evolution that remain undetermined. In order to improve the modeling of high energy particle collisions I study proton-gold collisions where previous evolution models fail to quantitatively describe the observed flow pattern. I have added sub-nucleonic structure and gluon field fluctuations to the energy density profiles created in nuclear collisions that we hope improves the description of light-heavy collisions. I show the effects of these fluctuations on the initial eccentricities that drive anisotropic flow of the QGP. I found increased ellipticity and triangularity which offer the chance to better reproduce the experimentally measured large elliptic and triangular flows seen in p$+$Pb collisions at the LHC. [Preview Abstract] |
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EA.00140: Beta Decay Study of Neutron-rich Magnesium John Ash, Mustafa Rajabali Within the ``island of inversion'' around the N = 20 shell gap, isotopes of magnesium, and aluminum deviate from the expected closed-shell structure. Particles promoted across the N = 20 shell gap result in a lower energy deformed ground state configuration rather than the expected spherical configuration. An experiment was conducted at TRIUMF laboratory in the summer of 2015 to study the decay of ``island of inversion'' isotopes $^{33,34,35}$Mg and the structure of the respective daughter nuclei. The isotopes of interest were produced by a proton beam from TRIUMF's 500 MeV cyclotron impacting on a UC$_{x}$ target. The magnesium decays populated states along the decay chain in Al, Si, P, and S isotopes. The new GRIFFIN spectrometer in the ISAC-I facility was used to detect the gamma rays. Two sets of scintillators, one for detecting the beta particles (SCEPTAR) and the other for detecting beta-delayed neutrons (DESCANT), were also used in conjunction with GRIFFIN. The GRIFFIN data were energy calibrated and partially analyzed for this project. New algorithms were developed for the analysis. Preliminary results for new transitions detected in $^{34}$Mg as well as the half lives obtained will be presented in their current form. [Preview Abstract] |
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EA.00141: Measurement of the neutron-capture cross section on 63,65Cu between 0.4 and 7.5 MeV Isabel Bray, Megha Bhike, (none) Krishichayan, W Tornow Copper is currently being used as a cooling and shielding material in most experimental searches for 0$\nu $$\beta $$\beta $ decay. In order to accurately interpret background events in these experiments, the cross section of neutron-induced reactions on copper must be known. The purpose of this work was to measure the cross section of the $^{{63},{65}}$Cu(n,$\gamma $)$^{{64},{66}}$Cu reactions. Data were collected through the activation method at a range of energies from approximately 0.4 MeV to 7.5 MeV, employing the neutron production reactions $^3$H(p,n)$^3$He and $^2$H(d,n)$^3$He. Previous data were limited to energies below approximately 3 MeV. The results are compared to predictions from the nuclear data libraries ENDF/B-VII.1 and TENDL-2014. [Preview Abstract] |
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EA.00142: Applicability of fluid-dynamical modeling of nucleus-nucleus collisions at relativistic energies Dean Hazineh, Jussi Auvinen, Marlene Nahrgang, Steffen Bass At sufficiently high temperatures and densities, similar to the conditions found in the early universe, QCD matter forms a deconfined state called the quark gluon plasma (QGP). This state of matter can be created in collisions of ultra-relativistic heavy-ions, and RHIC data suggests that this QGP behaves similar to an ideal fluid. Viscous relativistic fluid dynamics therefore is one of the preferred theoretical tools to model the time-evolution and properties of the QGP. As the collision energy or the system size is decreased, the range of applicability of viscous fluid dynamics becomes smaller as the length scale of the interaction among the basic constituents is similar to the overall scale of the collision system itself. In order to investigate the validity of fluid-dynamical modeling of proton-nucleus and nucleus-nucleus collisions at LHC and RHIC, we conduct an analysis of the spatial and temporal evolution of the Knudsen number, i.e. the ratio of the microscopic mean free path to the macroscopic length scale of the system. We show results for large and small collision systems, as a function of the specific shear viscosity, and discuss the range of applicability of fluid-dynamical modeling in relativistic proton-nucleus and nucleus-nucleus collisions at different energies. [Preview Abstract] |
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EA.00143: A Brierf Exploration of Low-Threshold, Gas-Filled Detectors Kirollos Masood Low-threshold detectors possess a wide variety of uses, such as detecting inverse $\beta$ decay. Additionally, with a sufficiently low threshold and low background, they could be sensitive enough for Coherent, Elastic Neutrino-Nucleus Scattering (CEvNS) and spin-dependent WIMP searches. Our aim was to explore prototypes and operating conditions of such gas-filled detectors. We have successfully operated at pressures from 1-30 psi (above atmosphere), and biases from 2-4 kV. These settings can be adjusted according to the desired energy range. Using an $^{55}$Fe source for calibration, we have achieved a threshold of 150 eV, under preliminary optimal conditions. As a result of moderate shielding, background radiation has been easily reduced to no more than 1000 counts kg$^{-1}$keV$^{-1}$day$^{-1}$. [Preview Abstract] |
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EA.00144: Nuclear Data Compilation for Beta Decay Isotope Susan Olmsted, John Kelley, Grace Sheu The Triangle Universities Nuclear Laboratory nuclear data group works with the Nuclear Structure and Decay Data network to compile and evaluate data for use in nuclear physics research and applied technologies. Teams of data evaluators search through the literature and examine the experimental values for various nuclear structure parameters. The present activity focused on reviewing all available literature to determine the most accurate half-life values for beta unstable isotopes in the A=3-20 range. This analysis will eventually be folded into the ENSDF (Evaluated Nuclear Structure Data File). By surveying an accumulated compilation of reference articles, we gathered all of the experimental half-life values for the beta decay nuclides. We then used the Visual Averaging Library, a data evaluation software package, to find half-life values using several different averaging techniques. Ultimately, we found recommended half-life values for most of the mentioned beta decay isotopes, and updated web pages on the TUNL webpage to reflect these evaluations. To summarize, we compiled and evaluated literature reports on experimentally determined half-lives. Our findings have been used to update information given on the TUNL Nuclear Data Evaluation group website. [Preview Abstract] |
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EA.00145: Development and Commissioning of an External Beam Facility in the Union College Ion Beam Analysis Laboratory Joshua Yoskowitz, Morgan Clark, Scott Labrake, Michael Vineyard We have developed an external beam facility for the 1.1-MV tandem Pelletron accelerator in the Union College Ion Beam Analysis Laboratory. The beam is extracted from an aluminum pipe through a 1/4'' diameter window with a 7.5-$\mu $m thick Kapton foil. This external beam facility allows us to perform ion beam analysis on samples that cannot be put under vacuum, including wet samples and samples too large to fit into the scattering chamber. We have commissioned the new facility by performing proton induced X-ray emission (PIXE) analysis of several samples of environmental interest. These include samples of artificial turf, running tracks, and a human tooth with an amalgam filling. A 1.7-MeV external proton beam was incident on the samples positioned 2 cm from the window. The resulting X-rays were measured using a silicon drift detector and were analyzed using GUPIX software to determine the concentrations of elements in the samples. The results on the human tooth indicate that while significant concentrations of Hg, Ag, and Sn are present in the amalgam filling, only trace amounts of Hg appear to have leached into the tooth. The artificial turf and running tracks show rather large concentrations of a broad range of elements and trace amounts of Pb in the turf infill. [Preview Abstract] |
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EA.00146: Inverse-kinematics Proton Scattering from 51Ca Sean Gregory We have studied 51Ca using inverse kinematics proton scattering. The experiment was run at the National Superconducting Cyclotron Laboratory (NSCL) using the GRETINA gamma-ray tracking array and the Ursinus College/NSCL liquid hydrogen target. We used geant4 simulations to extract gamma-ray intensities from the measured gamma-ray spectrum. The reaction populated five excited states of 51Ca. We observed a new gamma ray with an energy of 3950 keV. Preliminary results will be discussed. [Preview Abstract] |
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EA.00147: Simulation of the GRETINA Scanning Table at Lawrence Berkeley National Laboratory Ethan Haldeman We developed a GEANT4 simulation of the GRETINA scanning table at Lawrence Berkeley National Laboratory. The scanning table is used to study signal decomposition and to map the segmentation of GRETINA crystals. The data can also be analyzed to better understand characteristics of GRETINA like its geometry, resolution, and efficiency. The simulation is used both to plan measurements and interpret results. Complex components of the scanning table were implemented in the simulation using STL files created from CAD drawings which were imported to the code using the open source package CADMesh. Measurements of a GRETINA module will be presented and compared with simulations. [Preview Abstract] |
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EA.00148: Stability of the Gains of the STAR Endcap Calorimeter from 2009 to 2012 Chamindu Amarasinghe The Solenoid Tracker at RHIC (STAR) experiment, based at Brookhaven National Laboratory's Relativistic Heavy Ion Collider, uses polarized-proton collisions to investigate sea quark and gluon contributions to the known proton spin. The STAR detector's Endcap Electromagnetic Calorimeter (EEMC) is of particular interest in this experiment because it covers a kinematic region which is sensitive to gluons carrying a low fraction of the proton momentum, where the gluon spin is almost entirely unconstrained. The EEMC is located in the intermediate pseudorapidity range, $1 < \eta < 2$, and measures the electromagnetic energy of particles produced by the collisions using a lead-scintillator sampling calorimeter. The calorimeter consists of several layers that include pre-shower, shower maximum, tower, and post-shower detectors. In these detectors, the energy gains, which convert a measured signal into an energy deposition, have been determined using data taken from the years, 2009, 2011, and 2012. A comparison of the gains from the three years will be presented. [Preview Abstract] |
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EA.00149: A Voltage Multiplier for the nEDM Experiment Nathaniel Bouman, Shirantha Stanislaus The nEDM experiment at Oak Ridge National Laboratory aims to search for the electric dipole moment of the neutron (nEDM) at the $10^{-28}$ level. The experiment is currently at the research and development phase. One of the variables proportional to the sensitivity of the measurement is the strength of the electric field in the measurement cell where the effect of an nEDM is to be generated. The design of the experiment calls for an electric field of 75 kV/cm in this cell. A unique voltage multiplier involving a variable capacitor has been proposed to achieve this large required electric field. Electrostatic calculations using two independent software packages, COMSOL and Field Precision, were carried out to study the feasibility of the proposed voltage multiplier. A prototype of the electrodes and the voltage multiplier whose size was 25\% of full size was also built to verify the predictions of the electrostatic calculations. Results of the tests with the prototype and the electrostatic calculations, will be presented. [Preview Abstract] |
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EA.00150: New Analysis of levels in $^{103}$Mo H.L. Fryman-Sinkhorn, E.H. Wang, C.J. Zachary, J.H. Hamilton, A.V. Ramayya, Y.X. Luo, J.O. Rasmussen, S.J. Zhu Excited states of $^{103}$Mo have been studied by analyzing $\gamma $-$\gamma $-$\gamma $ and $\gamma $-$\gamma $-$\gamma $-$\gamma $ coincidence data from the spontaneous fission of $^{252}$Cf at Gammasphere. 23 new transitions and 12 new levels identified have been identified in this work. Spins and parities have been assigned based on systematics and their decay properties to the existing levels. The newly identified band has been assigned as a one-phonon $\gamma $ band by comparing the energy level spacings and transition energies with that of $^{104,105}$Mo. [Preview Abstract] |
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EA.00151: New analysis of levels in 147 La W.J. Lewis, E.H. Wang, C.J. Zachary, J.H. Hamilton, A.V. Ramayya, Y.X. Luo, J.O. Rasmussen, S.J. Zhu \newcommand{\g}{\gamma} Analysis of $\g\!-\!\g\!-\!\g$ and $\g\!-\!\g\!-\!\g\!-\!\g$ coincidence data from the spontaneous fission of $^{252}$Cf has been performed to identify new levels in $^{147}$La. These data were taken with Gammasphere at Lawrence-Berkeley National Laboratory. Twenty-two new transitions and fourteen new levels are established including a spin $39/2^+$ state and spin $47/2^-$ state. $^{147}$La lies very close to the center for octupole deformation; strong $E1$ transitions are observed connecting two opposite parity doublets validating this expected octupole deformation. Additionally, back bending in the moment of inertia plot is observed in one band. [Preview Abstract] |
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EA.00152: New energy levels in $^{107}$Mo J.L. Marcellino, E.H. Wang, C.J. Zachary, J.H. Hamilton, A.V. Ramayya, Y.X. Luo, J.O. Rasmussen, S.J. Zhu New energy levels and transitions in $^{107}$Mo have been established through the analysis of $\gamma $-$\gamma $-$\gamma $ and $\gamma $-$\gamma $-$\gamma $-$\gamma $ coincidence data from the spontaneous fission of $^{252}$Cf taken with Gammasphere. Twenty-five new transitions have been placed into eleven levels. Spins and parities are assigned tentatively by comparing the levels with $^{106,105}$Mo. Based on the energy level spacing, a one-phonon $\gamma $ vibrational band has been proposed similar to the ones observed in $^{106,105}$Mo. [Preview Abstract] |
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EA.00153: Surface reflectance and material studies for the PROSPECT Experiment Alyssa Bowes The PROSPECT Experiment aims to probe the existence of sterile neutrino oscillations by measuring the energy spectrum of antineutrinos emanating from nuclear reactors in a matrix of optically separated target scintillator cells at a variety of reactor-detector baselines. By measuring the absolute spectrum we also learn about reactors and what isotopes they produce. In order to properly model and optimise PROSPECT's energy resolution and background rejection capabilities, the reflective properties of the cell surfaces must be well understood. To address this, a study of various reflective surfaces under consideration to be used in the detector was conducted at non-normal incident angles through liquid using a custom-built laser-based reflectance measurement system. This presentation will describe the apparatus, reflectance measurements, and implications for the PROSPECT optical cell performance. Future plans to incorporate measurements into existing optical simulations will also be discussed. [Preview Abstract] |
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EA.00154: Coincident Muon Analysis Between the DM-Ice17 and IceCube Detectors Nikita Dutta DM-Ice17 is a direct detection dark matter experiment with two detectors located within the volume of the IceCube Neutrino Observatory at the South Pole. We report the use of muons coincident between DM-Ice17 and IceCube to verify muon identification in DM-Ice17 and provide a novel calibration technique for IceCube. Such events are unique within the IceCube data sample because they are known to pass through each 2,309\,cm$^3$ DM-Ice17 crystal volume within IceCube's 1\,km$^3$ total volume. Different muon track reconstruction techniques are explored to optimize resolution by minimizing distance from DM-Ice17 and maximizing accuracy in angles of approach. Reconstructions are performed both on data and simulation. Results indicate a strong improvement in the reconstruction accuracy of low-energy events with the addition of DM-Ice17 information. [Preview Abstract] |
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EA.00155: Characterization of Detector Response for PROSPECT -- A Precision Reactor Oscillation and SPECTrum Measurement Brian Goddard, Michelle Dolinski Recently, several experiments have reported an approximately 5{\%} deficit of antineutrinos from nuclear reactors when the measured flux is compared with that predicted by current nuclear models. This is termed the ``Reactor Antineutrino Anomaly''. Furthermore, the predicted shape of the antineutrino spectrum is not in agreement with measurements from those experiments. The PROSPECT (Precision Reactor Oscillation and SPECTrum Measurement) collaboration plans to investigate this anomaly and constrain the shape of the spectrum with a high precision, short baseline (7-20m) measurement of the antineutrino spectrum from Oak Ridge National Laboratory's High Flux Isotope Reactor (HFIR) which will include a search for sterile neutrinos as one possible solution to the anomaly. PROSPECT will utilize a segmented, lithium-loaded liquid scintillator detector and is taking a phased approach to detector design by building progressively larger prototypes of this final detector with several prototypes already constructed and taking data. This poster will report on the ongoing analysis of the detector response of these prototypes including aspects such as position reconstruction, energy resolution, and pulse shape discrimination. [Preview Abstract] |
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EA.00156: Temperature Dependence of Pulse Shape in Sodium Iodide Field Rogers Thallium-doped sodium iodide (NaI(Tl)) scintillating crystals are used as the sensitive detectors in several direct detection dark matter experiments. DM-Ice is a NaI(Tl) dark matter experiment which employs pulse shape discrimination methods for background characterization and event selection. An understanding of the temperature dependence of NaI(Tl) response is required to compare experimental locations and run parameters. The first generation detector, DM-Ice17, is operating under a 2200 m.w.e. overburden in the South Pole ice at -20$^{\circ}$C. Meanwhile, a set of R$\&$D test detectors, DM-Ice37, is operating under a 2850 m.w.e. overburden in the Boulby Underground Laboratory at +20$^{\circ}$C. We describe the differences in pulse shape and light yield at varying temperatures for gamma, alpha, and neutron scintillation events in NaI(Tl) and demonstrate temperature dependence for NaI(Tl) scintillations across a broad range of energies. [Preview Abstract] |
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EA.00157: Widening the Scope of a Partial Dynamical Symmetry Wesley Pereira, Ricardo Garcia, Larry Zamick In a single j shell calculation in which only T=1(even J) two-particle matrix elements were non-zero there was a partial dynamical symmetry e.g. for 2 protons and 2 neutrons in the f$_{7/2}$ shell there is a degeneracy of states with angular momenta I=3,7,9,10. These have non -zero components only for (J$_{p}$, J$_{n}$) =(4,6) or (6,4). These I's cannot occur for 4 identical partices ($^{44}$ Ca).We then consider a ``123'' interaction which for J=0 to 7 is (0,0,1,0,2,0,3,0). Then I=6 and I=8 also come into play. Fot these (J$_{p}$+J$_{n}$ ) is a good quantum number .One gets an equally spaced multidegerate levels ( ``vibrational spectra'') with separation of 1.5 MeV. Each of these levels has fixed (J$_{p}$ +J$_{n}$ . For (J$_{p}$+J$_{n}$) equal to 6 we have I=3 an I= 6 as ;for 8 we get 6,7 ,8; for 10,we get 3,7,9,10 and for 12 we get 10,12. In the g$_{9/2}$ shell with a ``1234''(J$_{p}$ +J$_{n}$) ranges from 8 to 16 and in h$_{11/2}$with ``12345'' from 10 and 20. [Preview Abstract] |
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EA.00158: On the Optimization of Homogenous Light Output in Scintillator Panels for the sPHENIX Collaboration Sebastian Vazquez-Carson The sPHENIX detector at RHIC will contain an electromagnetic and a hadronic calorimeter used for the detection of particles ejected in jets from heavy ion collisions. The hadronic calorimeter will be composed of layers of steel plates that are alternated with plastic scintillators. Within the scintillator panels, wavelength shifting fiber optic cables are embedded and coupled to silicon photo multipliers (SiPMs). The signal from the SiPMs pass through a preamp that shapes and amplifies the signal before passing it to a analog to digital converter (ADC) from which the energy deposited in the scintillator is calculated. The scintillator panels are manufactured with a diffusive coating to improve reflection and increase sensitivity. With the test setup at the University of Colorado at Boulder, we explored the correlation between the presence and density of the diffusive coating and the uniformity of light output within the panels. We prototyped various SiPM mounting systems and characterized the performance of the preamps with the aim of optimizing light collection, panel response sensitivity, and signal clarity. [Preview Abstract] |
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EA.00159: Optical Simulations and Studies with the PROSPECT-20 Detector Nathaniel Stemen The PROSPECT (Precision Reactor Oscillation and SPECTrum) experiment at the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory will make a precise measurement of the reactor antineutrino spectrum from a highly-enriched uranium nuclear reactor while also probing for short-baseline oscillations as a signature of possible sterile-neutrinos. Two liquid scintillator detectors at distances of 7-10m and 16-20m from the reactor will identify inverse beta decay events initiated by reactor antineutrinos. The near detector will be divided into optically separated segments filled with lithium loaded liquid scintillator read out by photomultiplier tubes (PMTs) on either end. Light guides will be employed to direct photons from the scintillator cells to the active PMT photo-cathodes. An optical simulation was built to optimize the performance of the detectors with respect to both light collection and detector uniformity and guide the design of the scintillator cells. We present experimental data and simulation results from the PROSPECT-20 prototype detector. [Preview Abstract] |
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EA.00160: Tungsten Scintillating Fibers Electromagnetic Calorimeters for sPHENIX upgrade Siyang Li, Vera Loggins, Michael Phipps, Anne Sickles sPHENIX, a planned new detector at RHIC, features electromagnetic and hadronic calorimetry that covers {\textbar}$\eta ${\textbar} {\textless} 1.1 and $\varphi $ = 2$\pi $. The large acceptance calorimeter design is optimized for the study of jets in heavy ion collisions. The design includes a tungsten fiber EmCal that is made out of a tower array of plastic scintillating fiber embedded inside a mixture of tungsten powder and epoxy. For this calorimeter, silicon photomultipliers will be attached at the end of the module to convert scintillated optical photons into electrical signals. The sPHENIX group at Illinois is currently making samples of these modules to study the production process and achievable density. In addition, we have set up a silicon photomultiplier read out test system which will be used to evaluate the module performance. [Preview Abstract] |
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EA.00161: A cross-platform GUI to control instruments compliant with SCPI through VISA Eric Roach, Jing Liu In nuclear physics experiments, it is necessary and important to control instruments from a PC, which automates many tasks that require human operations otherwise. Not only does this make long term measurements possible, but it also makes repetitive operations less error-prone. We created a graphical user interface (GUI) to control instruments connected to a PC through RS232, USB, LAN, etc. The GUI is developed using Qt Creator, a cross-platform integrated development environment, which makes it portable to various operating systems, including those commonly used in mobile devices. NI-VISA library is used in the back end so that the GUI can be used to control instruments connected through various I/O interfaces without any modification. Commonly used SCPI commands can be sent to different instruments using buttons, sliders, knobs, and other various widgets provided by Qt Creator. As an example, we demonstrate how we set and fetch parameters and how to retrieve and display data from an Agilent Digital Storage Oscilloscope X3034A with the GUI. Our GUI can be easily used for other instruments compliant with SCPI and VISA with little or no modification. [Preview Abstract] |
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