Bulletin of the American Physical Society
2006 Division of Nuclear Physics Annual Meeting
Wednesday–Saturday, October 25–28, 2006; Nashville, Tennessee
Session 3A: CEU Poster Session |
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Chair: Warren Rogers, Westmont College Room: Gaylord Opryland Cheekwood ABC, 12:30pm - 2:00pm |
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3A.00001: An Automated Relative Time Calibration for the MoNA Daniel Albertson The Modular Neutron Array (MoNA) is a highly efficient time-of-flight neutron detector consisting of 144 individual plastic scintillation bars. It is used in conjunction with a sweeper magnet and charged particle detectors at the National Superconducting Cyclotron Laboratory to reconstruct neutron separation energies of neutron unbound nuclei from the velocities of the ejected neutrons and residual fragments. The PMT signals from each bar in the array have slightly different transit times. An offset to calibrate the bars relative to each other must be calculated using cosmic ray muons. The current relative calibration employs a labor intensive and imprecise method. A more precise procedure for finding the weighted average of the time difference between any two bars and calculating the calibration values was developed and automated. Details of the procedure will be presented. [Preview Abstract] |
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3A.00002: In-beam gamma-ray spectroscopy of 172Os K. Aleksandrova, P. Manchev, M.S. Fetea, A. Heinz, G. Gurdal, R. Casperson, R.F. Casten, M. Chamberlain, E.A. McCutchan, J. Qian, N.J. Thompson, V. Werner, R. Winkler A 30Si beam was used for a test experiment at the WNSL facility. The production of the compound nucleus 174Os was achieved through complete fusion in a 100 $\mu $g/cm2 144Sm target at beam energy of 134MeV. Gamma-rays from residual nuclei were detected with the YRAST ball array consisting of 7 Compton-suppressed clover detectors. A number of Os isotopes, in particular 172Os were also detected. While the main goal of the experiment was the commissioning of a gas-filled detector, we present here data from in-beam gamma-ray spectroscopy. [Preview Abstract] |
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3A.00003: Testing and Evaluation of PHENIX Reaction Plane Detector Photomultiplier Tubes Nicholas Anderson, Eric Richardson, Alice Mignerey The PHENIX Reaction Plane Detector (RxnP) at the Relativistic Heavy Ion Collider is designed to determine the reaction plane in heavy ion collisions. Currently the reaction plane is determined using the Beam Beam Counters. However, the RxnP will increase the resolution by nearly a factor of two over the currently achievable levels. This detector's location in the central region of PHENIX will expose it to a magnetic field of approximately 1 Tesla. The curvature of the field lines makes it necessary to understand the relationship between the angle of the photomultiplier tubes (PMTs) in the magnetic field and the PMTs' output. Results of bench-top tests of the PMTs in similar magnetic fields and their impact on the final design will be presented. [Preview Abstract] |
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3A.00004: Precision (n,$\gamma$) cross-section measurement of Cu at 8 and 12 MeV for shielding designs for the next generation of $\mathbf{0\nu\beta\beta}$ decay experiments. M. Antonacci, A. Chyzh, J.H. Esterline, S. Elliot, B. Fallin, A. Hime, C.R. Howell, A Hutcheson, H.J. Karwowski, J.H. Kelley, M.F. Kidd, D. Mei, B. Spaun, A.P. Tonchev, W. Tornow Renewed interest in observing $0\nu\beta\beta$ decay reactions has sparked efforts to experimentally verify the existence of such decays, and produce new physics beyond the Standard Model. These reactions, with half-lives around 10$^{27}$ years, require an extensive understanding of background sources. The potential for neutron induced excitation of the shielding and detector materials is important for understanding and designing future $0\nu\beta\beta$ decay experiments. Gamma transitions at 2041, 2615, and 3062 keV directly obscure $0\nu\beta\beta$ decay detection of $^{76}$Ge at 2040 keV. Due to lack of experimental information in the nuclear database, high-resolution $\gamma$-ray spectra from the interaction of mono-energetic and pulsed neutrons were measured at TUNL. The emitted gamma rays were detected with 3 HPGe segmented clover detectors at 62$^{\circ}$, 90$^{\circ}$, and 135$^{\circ}$. From these data, partial cross-sections for prominent $\gamma$ transitions in $^{63,65}$Cu were derived at En=8 and 12 MeV. This experimental information will also help to understand the existing $0\nu\beta\beta$ data and serve as a benchmark for statistical model calculations. Supported in part by DOE grant DE-FG02-97ER41033 and NSF grant NSF-PHY-05-52723. [Preview Abstract] |
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3A.00005: New precise $\alpha_{K}$ measurement as part of a test of electronic conversion theory - 166 keV transition in $^{139}$La Christine Balonek, Ninel Nica, John Hardy Precise internal conversion coefficients (ICCs) are crucial to the study of nuclear decay schemes, including spin and parity designations, transition rates, and branching ratios. However, various calculations of ICCs disagree with one another and with experiment by several percent. The situation is further confused by the fact that very few ICC measurements have uncertainties under 1{\%}. Until recently, it was even unclear if the calculations should incorporate the hole left by the departing conversion electron. To remedy this situation, we have set out to measure the K-shell ICC values of three different isotopes to that precision. The ICCs for 127.55 keV E3 transition of $^{134}$Cs$^{m}$ and 661.657 keV M4 transition of $^{137}$Ba have already been completed. We report here on the third and final case: the 165.858 keV M1 transition in $^{139}$La. [Preview Abstract] |
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3A.00006: Modeling nuclear stopping with in-medium modifications of nucleon-nucleon cross sections. Brent Barker, Pawel Danielewicz Stopping in heavy ion collisions is investigated with the aim of understanding microscopic dynamics of collisions and transport properties of nuclear matter. Boltzmann-equation simulations are compared to available data on stopping in the energy range between 0.02 A and 1.5 A GeV. Stopping observables used include momentum anisotropy, linear momentum transfer, and isospin tracing. The data clearly shows that modeling the transport with free elementary cross-sections is inaccurate and reduced cross-sections are required. Reduction of the cross-sections produce an increase in transport coefficients of nuclear matter, compared to calculations based on free cross-sections. [Preview Abstract] |
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3A.00007: RPC Detector Research and Development for PHENIX Austin Basye PHENIX, an experiment located on the RHIC ring at Brookhaven National Laboratory, is currently studying heavy ion collisions and polarized proton-proton collisions. To increase the effectiveness of the existing detector systems, Resistive Plate Chambers (RPCs) have been proposed for a level 1 trigger upgrade for the Muon Spectrometer Arms. These RPCs will improve W boson reconstructions from single high Pt muons by rejecting a large low Pt moun event background. This background will become larger as RHIC begins 500 Gev proton-proton collisions at higher luminosities. RPCs are currently being installed at all the major experiments at LHC, and it is from CMS, principally, that we have patterned the bulk of our design proposals. Based upon simulations, significant progress has been made to model signal pad layout, the mechanical structure and acceptance, and overcome design obstacles related to read-out and gas gap design. [Preview Abstract] |
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3A.00008: Primordial Nucleosynthesis of Lithium Isotopes Janilee Benitez, George Fuller, Chad Kishimoto, Christel Smith A key issue in modern cosmology involves the synthesis of Lithium in the early universe. We investigate the production of $^6$Li and $^7$Li in primordial nucleosynthesis. We discuss key nuclear reaction rates and the effects of lepton degeneracy. [Preview Abstract] |
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3A.00009: Integrating Wireless Networking for Radiation Detection Jeremy Board, Alexander Barzilov, Phillip Womble, Jon Paschal As wireless networking becomes more available, new applications are being developed for this technology. Our group has been studying the advantages of wireless networks of radiation detectors. With the prevalence of the IEEE 802.11 standard (``WiFi''), we have developed a wireless detector unit which is comprised of a 5 cm x 5 cm NaI(Tl) detector, amplifier and data acquisition electronics, and a WiFi transceiver. A server may communicate with the detector unit using a TCP/IP network connected to a WiFi access point. Special software on the server will perform radioactive isotope determination and estimate dose-rates. We are developing an enhanced version of the software which utilizes the receiver signal strength index (RSSI) to estimate source strengths and to create maps of radiation intensity. [Preview Abstract] |
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3A.00010: Behavior of a Radial Time Projection Chamber Peter Bradshaw Using Gas Electron Multiplying (GEM) foils for amplification, the detector allows for three-dimensional representations of particle tracks through two half cylinders filled with gas. Developed for the Bound Nucleon Structure (BONUS) experiment at Jefferson Lab, the RTPC allows experimenters to study the quark composition of the neutron by scattering electrons from deuterium nuclei. The defining feature of the detector is that it allows for a complete view of the interaction of the electron and target gas, including the protons left over after a reaction on the neutron. This experiment seeks to understand the efficiency of the detector and its amplification (signal strength for a given ionization, as a function of detector gas and high voltage), by making a measurement of the amount of energy deposited in the chamber per unit length from cosmic radiation. In order to test each half of the Radial Time Projection Chamber we use an 85{\%} Helium and 15{\%} Dimethyl Ether (85/15 HeDME) and an 80/20 HeDME at optimal voltages to detect cosmic particles. The detector takes an electronic snapshot of the incident particle by examining the charge deposited as a function of time. The importance of this technology should not be underestimated. Radial Time Projection Chambers could, in some applications, replace current Time Projection Chambers and Wire Chambers. [Preview Abstract] |
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3A.00011: Implementation of PC's in Control Systems for Large Physics Experiments Jennie Burns Traditionally large physics experiments have used dedicated specialized processors for their control systems. Increased processor speed has permitted the use of personal computers for the control and monitoring of these experiments. The control system for the STAR (Solenoidal Tracker At RHIC) experiment was implemented using VME-based front end processors for detector control and graphical work stations as the user interfaces. The system is being revised to accommodate new detector subsystems and to replace ten year old hardware with PC's which are less expensive and more easily maintained. The hardware control system for ALICE (A Large Ion Collider Experiment) is being developed in a PC-based environment. Personal computers are used for both front end functions and the user interface. The original STAR control system is compared with the upgraded system. The architecture and the implementation of the control system for the ALICE experiment are also presented. Comparisons between the STAR and ALICE systems are outlined. [Preview Abstract] |
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3A.00012: CLAS Simulations for $D(\vec e,e^\prime p)n$ Robert Burrell, Kuri Gill, Gerard Gilfoyle We are simulating the electrodisintegration of the deuteron in the $D(\vec e,e^\prime p)n$ reaction in the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. CLAS is a large, complex particle detector that measures the debris from collisions of electron and photon beams with nuclear targets with nearly $4\pi$ solid-angle coverage. To better understand the response of CLAS, to calculate its acceptance, and to test our analysis codes, we simulate the detector's performance. Working on the University of Richmond's supercomputing cluster, we have written a Perl script to perform the simulation by executing a sequence of commands running different programs, managing files, {\it etc}. We use a model of quasi-elastic scattering called QUEEG (Quasi-Elastic Electron Generator) to generate the initial four-vectors for each event. These events pass through a GEANT simulation of CLAS, are reconstructed with standard CLAS software, and final-stage analysis of the reconstructed four-vectors is performed with ROOT. We will report results of the application of this technique to the measurement of asymmetries in CLAS for the 2.56-GeV, reversed-polarity data set of the E5 running period. [Preview Abstract] |
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3A.00013: Characterization of Silicon Tetra-lateral PSDs Zhon Butcher This research project characterized the tetra-lateral position sensitive detectors (PSDs) in terms of energy and position resolution as well as non-linearity in position reconstruction. Measurements were made of impinging positions of alpha particles on three different PSDs. One 200 um and one 400 um thick detector with a resistive strip and one 200 um thick detector without the strip were tested. The resistive strip was framed around the detector active area and was approximately 1/10th the resistance of the active area. The detector with no resistive strip produced a very pronounced ``pin-cushion'' effect when the position data was analyzed. The 200 um thick detector with the resistive strip produced much greater energy and position resolution. This resolution of both energy and position was found to be enhanced by the 400 um thick detector. Optimal energy and position resolution were obtained with the 400 um detector using Indiana University preamplifiers in conjunction with a CAEN amplifier using a 3us shaping time. Energy and position resolution were found to be dependent on the type of preamplifier used as well as the shaping time of the amplifier. Further investigations of these dependencies are ongoing. [Preview Abstract] |
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3A.00014: A study on the reflectivity of Tyvek Alvaro Chavarria Tyvek is a permeable, strong, white material made by Dupont. Due to its high reflectivity, many physics experiments use Tyvek to increase the collection of light. The Super-Kamiokande neutrino experiment in Japan uses this material extensively in its outer detector and its reflective properties are part of the Super-K Geant3 Monte Carlo simulation. Currently, the reflective properties of Tyvek that are in the Super-K simulation are not precisely known. Thus, a good way to improve the outer detector (OD) simulation might be to implement a more realistic model for the reflection of photons on the Tyvek surface. An experiment was developed to measure the reflectivity (percentage of light reflected at a particular angle for a particular angle of incidence of the incoming photons) of Tyvek under water, for all angles of incidence and all angles of reflection. Preliminary results have been obtained and will be presented at the conference. Once all results are in, it will be attempted to fit the reflectivity function to Lambert's cosine law or some variation of it. After a successful experimental fit is found, the model will be implemented into Super-K's Monte Carlo simulation. [Preview Abstract] |
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3A.00015: Measuring scintillation light using Visible Light Photon Counters (VLPC) Alvaro Chavarria A new search for the neutron electric dipole moment (EDM) using ultra cold neutrons proposes an improvement on the neutron EDM by two orders of magnitude over the current limit (to $10^{-28}$ e*cm). Detection of scintillation light in superfluid $^4$He is at the heart of this experiment.\\ One possible scheme to detect this light is to use wavelength-shifting fibers in the superfluid $^4$He to collect the scintillation light and transport it out of the measuring cell. The fiber terminates in a visible light photon counter (VLPC). VLPCs are doped, silicon based, solid state photomultipliers with high quantum efficiency (up to 80\%) and high gain ($\approx$40000 electrons per converted photon). Moreover, they are insensitive to magnetic fields and operate at temperatures of $\approx$6.5K.\\ A test setup has been assembled at Duke University using acrylic cells wrapped in wavelength-shifting fibers that terminate on VLPCs. This setup is being used to evaluate the feasibility of this light detection scheme. The results obtained in multiple experiments done over the past summer (2006) and the current status of the project will be presented at the conference.\\ Reference:\\ A New Search for the Neutron Electric Dipole Moment, funding pre-proposal by the EDM collaboration; R. Golub and S. Lamoreaux, Phys. Rep. 237, 1 (1994). [Preview Abstract] |
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3A.00016: B(E2) in heavy Pd nuclei through the time-of-flight method Aaron Chester The onset of deformation in even nuclei is manifested by a decreasing energy of the 2$^{+}$ excited state, E(2$^{+})$, correlated with an increase in the reduced transition probability B(E2). It is surprising to observe for A$\ge $110 Pd nuclei that as E(2$^{+})$ decreases so does B(E2) as reported by the National Nuclear Data Center. This trend was investigated with the time-of-flight method using a plunger device designed in collaboration with the University of Cologne, Germany. The plunger consists of a moveable target and a stationary passive degrader. A fast beam of $^{114}$Pd was Coulomb-excited to the 2$^{+}$ state on the plunger target. The degrader, downstream of the target, was used to slow the nuclei. Gamma-rays emitted before and after the degrader were measured at different Doppler shifts due to the change in velocity. A modified Segmented Germanium Array setup used for gamma-ray detection provided an optimal balance of sensitivity to changes in velocity and energy resolution. The ratio of the peak intensities yields information about the lifetime of the state of interest. A new B(E2) value was found for $^{114}$Pd that is twice as large as the previous measurement, but follows the expected trend. [Preview Abstract] |
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3A.00017: Graphic User Interface for the NIMROD Silicon Detectors Christopher Crane Graduate student Sara Wuenschel and I created the ``Bias Box Control v3.2'' Graphic User Interface program. It was designed with the intent of monitoring voltage and current while biasing to Nimrod's detectors rings, including the newest addition to the Texas A\&M Cyclotron Institute ISIS a spherical particle detector. NIMROD and ISIS are both nuclear particle detectors located in the Texas A and M cyclotron. The program takes user input values and sends Biasing voltages to NIMROD's various rings. The GUI also monitors the actual charge held in the detectors of a specified ring, and the leakage current on a specific silicon of that ring. An experimentalist can load ``voltage'' files, save voltage values, set all channels at once, set all channels to zero, Refresh the monitoring status of the ADC, and change a voltage array load file. The current status of the GUI is functional and future revisions of versions may include support for Ion Chambers. The program was created in Linux but can easily be ported over to Windows and Macintosh formats. [Preview Abstract] |
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3A.00018: Analyzing Sources of Uncertainty in a Precision Measurement of $^3$He($\alpha, \gamma)^7$Be A.M. Crisp, T.A.D. Brown, C. Bordeanu, K.A. Snover, D.W. Storm The $^3$He($\alpha, \gamma)^7$Be reaction plays an important role in the solar p-p chain. The uncertainty in this reaction rate is currently the largest nuclear physics uncertainty in solar model calculations of the neutrino flux from the decay of both $^7$Be and $^8$B in the sun. At CENPA we are measuring the low energy cross section for this reaction at center-of-mass energies of 1.2 MeV and lower, using a $^3$He gas cell with a thin nickel entrance window. The goal of this experiment is to determine the astrophysical S-factor to $\pm$5\% or better, from measurements of both the prompt $\gamma$’s and the $^7$Be activity produced in the same irradiation. In order to reach this goal one must measure and minimize the important systematic errors. We will discuss beam heating of the target gas, sources of background radiation, and detector efficiency, as well as other important aspects of the experimental technique. [Preview Abstract] |
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3A.00019: Upstream Photon Veto Studies for the GlueX Project James Custer The Upstream Photon Veto (UPV), being developed at Florida State University, is a sampling electromagnetic calorimeter that will become part of the GlueX project. The detector will be placed upstream of the photon beam. The main goal of this detector is to veto photons in the backwards direction of the target. This study looks to optimize the detector configuration for resolution and efficiency. To do this, we've modeled the detector in the Geant4 simulation toolkit. Past studies have shown that the optimal configuration is 12 layers of lead-scintillator followed by 6 layers of double the thickness of lead, and scintillator. In this study, we test how the resolution and efficiency respond to changing the number of layers with a fixed total volume, by changing the sizes of the layers overall, and the addition of a pre-radiator. The results have shown that we can most effectively increase our resolution and efficiency by doubling the thickness of the scintillator, or by doubling the number of layers, but keeping the same overall volume. [Preview Abstract] |
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3A.00020: Environmental Radiation Measurements of Sea Sponges (\textit{Microciona prolifera }and\textit{ Halichondria bowerbanki}) Berta Darakchieva, Miloslava Evtimova, Cornelius Beausang, Shelly Lesher, Malcolm Hill The applications of radiometrics in the ecological sciences are numerous and of increasing importance. It is a powerful technique that can be used both for tracing various biological processes and for assessing levels of radioactive pollution in the environment. The aim of this project is to gather information on the levels of radioactivity in the Chesapeake Bay area by evaluating the radiation dose concentrations in sea sponges. Microciona prolifera and Halichondria bowerbanki, which are abundant in the Bay, serve as experimental organisms. A radiometric test is performed with two HPGe detectors located at the University of Richmond to identify any radionuclides present in the sponges. In order to increase the efficiency of the measurements, the collected sponges are frozen and ground in liquid nitrogen, thus forming a sample of condensed biomass which can be close packed around the germanium detector. The analysis includes measurement of the relative intensities of the detected gamma rays and identification of the elements. The spectral data will be used to calculate DCCs (dose conversion coefficients for the species), which will be compared with the values typical for natural radioacitvity and for anthropogenic contamination. This work is partly supported by the U.S. DOE under grant numbers DE-FG52-06NA26206 and DE-FG02-05ER41379 and by the University of Richmond HHMI fellowship. [Preview Abstract] |
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3A.00021: Modeling a Graphite Diagnostic System using MCNPX J. Deaven, S.L. Stephenson, S.J. Padalino, V. Yu. Glebov, T.C. Sangster Inertial Confinement Fusion (ICF) implosions can be characterized by the target areal density ($\rho $R). The $\rho $R of ICF targets in the National Ignition Facility (NIF) target chamber can be determined by tertiary-induced neutron activation of elements with appropriately high thresholds. In such materials as $^{12}$C, neutron activation results in beta decay and the emission of 511-keV coincidences which are detected by a pair of NaI(Tl) detectors. Optimal diagnostic thickness, contamination effects, and detector response have been modeled using MCNPX. Results will be presented. [Preview Abstract] |
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3A.00022: Analysis of Kinematics and Decay Energy in the Breakup of $^{7}$He Deborah Denby, Paul DeYoung, Graham Peaslee The energy resolution of the Modular Neutron Array and Sweeper magnet was studied by measuring the breakup of $^{7}$He. A 40 MeV/A $^{7}$Li beam was produced with the coupled cyclotrons at the National Superconducting Cyclotron Laboratory and following proton stripping in a Be target unstable $^{7}$He were produced. After breakup of the $^{7}$He into $^{6}$He and a neutron, the resultant charged fragments were deflected by the Sweeper magnet and detected, and the corresponding neutrons were detected in MoNA. The decay energy of $^{7}$He was calculated based on reconstructed fragment and neutron energies. Further analysis is in progress to verify results and determine uncertainty. Analysis procedures and the setup and operation of the experiment will be presented. Decay energy results and implications will also be discussed. [Preview Abstract] |
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3A.00023: Lifetime of the first excited state in $^{64}$Ge using the time-of-flight method. Athena DuNomes Picosecond lifetime measurements using the relativistic time-of-flight plunger method were performed at the NSCL from fragmentation and knockout reactions. The experiment was aimed at the predicted 5.4 ps lifetime of the $^{64}$Ge first excited state and tested the limits of the method. The $^{65}$Ge beam was delivered from the A1900 separator and impinged on the target of the plunger. The ensuing single neutron knockout reaction produced $^{64}$Ge nuclei. These excited nuclei emerged from the target and decayed in flight after a distance corresponding to the lifetime. A moveable reset foil positioned downstream from the plunger target was used to reduce the velocity of the investigated nuclei. As a consequence, the gamma rays, which decayed from the excited states before and after the degrader foil, were detected at different Doppler shifts by a modified Segmented Germanium Array setup with forward and backward rings at 30\r{ } and 140\r{ } with respect to the beam axis. The obtained decay curve provides information about the lifetime since the distance between the target and degrader foils and beam velocity are known. The result of the lifetime measurement will be presented. [Preview Abstract] |
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3A.00024: Off-Axis Calibration of KamLAND and Modeling of the ``FourPi'' Calibration System Gilly Elor KamLAND is 1000-ton liquid scintillator detector which uses the prompt and delayed signals from inverse beta decay to detect electron anti-neutrinos produced in nuclear reactors. KamLAND has made the first observation of the disappearance of reactor electron anti-neutrinos. The largest contribution to the systematic uncertainty in KamLAND is the fiducial volume uncertainty (4.7 $\%$ out of a total 6.5 $\% $). Until now the detector has been calibrated using gamma-ray sources of known energy deployed along the detector's vertical axis. A new 4$\pi$ calibration system allows for off-axis source deployment throughout the entire fiducial volume. The $4 \pi$ system is expected to reduce the fiducial volume uncertainty from 4.7 $\%$ to $\sim$ 1-2 $\% $, and improve KamLAND's sensitivity in the determination of the mass-difference parameter $ \Delta m_{12} ^{2} $. The 4$\pi$ system is currently in the initial stages of off-axis deployment. An off-line calculation is used to predict the location of the gamma-ray sources within the detector. The calculation takes into account the systems geometry, buoyancy effects in the liquid scintillator, and gravitational deflection of the 4$\pi$ pole from its neutral axis (deflection correction incorporates both a theoretical model, and survey data). Comparison of the predicted source location with the vertex reconstructed using the KamLAND analysis software, allows for an investigation of the biases in the reconstruction procedure. [Preview Abstract] |
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3A.00025: Investigating the Structure of High-Spin Francium M. Evtimova, C. Beausang, B. Darakchieva, B. Crider, R.B. Cakirli, V. Werner, D. Meyer, E. Novitski, G. Gurdal, J. Qian, L. Amon, R. Casperson, C. Fitzpatrick The purpose of this research is to investigate the structure of high-spin nuclei with odd atomic number, in particular Francium 209 and Francium 210 nuclei. This experiment was done in the Wright Nuclear Structure Laboratory at Yale University in the summer of 2005. I have been involved in the analysis of these results since September 2005. In the experiment a gold target is bombarded by a beam of accelerated oxygen ions. The beam was supplied by the ESTU accelerator at WNSL. Au-197 and O-16 nuclei fuse to produce Fr-213, which then ``evaporates'' neutrons, resulting in Fr-209 (4n) and Fr-210 (3n). These Fr nuclei emit gamma rays in order to lower their energy and achieve their ground states. These gamma rays were detected using the gamma detector array YRAST Ball, and the spectra they produce reveal information about the energy difference between levels in the level scheme. However, the gamma ray spectra do not directly show the order in which the transitions occur. Therefore, I am using various spectral analysis techniques, including gamma-gamma coincidences and gamma correlations, in order to determine what energies and what transformations are allowed for these nuclei. I have already found new information about both nuclei. However, there are still some discrepancies in the data for Fr-210. I am going to continue working on them, and I hope to resolve the problems soon. [Preview Abstract] |
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3A.00026: An Analysis of Simulated Identified Particle Spectra in ALICE at Intermediate and High Transverse Momentum Xieyue Fan High transverse momentum ($\mathrm{p_{T}}$) particles have provided a wealth of information on the hot and dense matter created in heavy-ion collisions at the Relativistic-Heavy Ion Collider (RHIC) at BNL. Charged, high-$\mathrm{p_{T}}$ particles were observed to be suppressed relative to binary scaling. Also, a difference between baryon and meson spectra at intermediate $\mathrm{p_{T}}$ was found. With the startup of the Large Hadron Collider (LHC) at CERN coming in 2007, it will be interesting to see how these effects evolve with increasing beam energy. To explore the capabilities of the ALICE experiment, we present an analysis of simulated events from \textsc{Pythia} ($p+p$) and HIJING (Pb+Pb) at 5.5 TeV/Nucleon. Particles from these simulated events are propagated through the ALICE GEANT model and reconstructed using the full software chain. Characterizations of identified particle spectra and yields are presented, with focus on the high $\mathrm{p_{T}}$ region. [Preview Abstract] |
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3A.00027: Nuclear and Nucleon Compton Scattering at the High Intensity Gamma Ray Source (HI$\gamma $S) and Commissioning of the \underline{HI}$\gamma$S \underline{N}aI \underline{D}etector \underline{A}rray (HINDA) W. Frederick, M.W. Ahmed, H.R. Weller The availability of a high intensity, nearly monochromatic, linearly or circularly polarized gamma ray beam at the Duke Free Electron Laboratory has set the stage for unprecedented precision measurements of the electric, magnetic, and spin polarizabilities of the neutron. These measurements will be performed by Compton scattering polarized gamma rays from polarized proton, deuteron, and $^{3}$He targets. In order to perform these measurements, a geometrically flexible, highly efficient NaI detector array with a large photon acceptance, dubbed HINDA, is being constructed. The HINDA detectors will be contained in 2'' thick segmented NaI anti-coincidence shields, in order to produce high resolution background free spectra. This research lays the foundation for HINDA's assembly. The purpose of this research was to maximize the energy resolution of the HINDA detectors utilizing an AmBe source and to establish an identification and record system to facilitate its assembly. [Preview Abstract] |
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3A.00028: Spin Polarization Diagnostics for Magneto-optical Trapped $\beta^{+}$-Decaying Atoms A. Gaudin, C. H\"{o}hr, D.G. Roberge, J.R.A. Pitcairn, M.R. Pearson, J.A. Behr To test the degree of parity violation in $\beta$ decay, the spin polarization of the decaying atoms must be known. In the TRIUMF Neutral Atom Trap project, the polarization of decaying atoms is achieved through optical pumping, which is a random walk through atomic spin states, biased to higher angular momenta with circularly polarized light. This poster presents work on spin polarization diagnostics for trapped $^{41}$K. $^{41}$K serves as a stable test base for $\beta^{+}$-decaying $^{37}$K and $^{80}$Rb, due to its similar hyperfine structure. Experimental techniques for measuring the fluorescence produced during the optical pumping are detailed. As the atom population is pumped to higher polarization states the atoms are excited less frequently and produce less fluorescence. Experimental tests precisely comparing measurements of the fluorescence and the excited state population, as determined by photoionization, will be shown; only the latter can be measured due to the small number of atoms. The circular polarization of the fluorescence also varies with atomic polarization. In addition, two computational models of the pumping process, used to fit to the data to obtain polarization values, will be presented. Determination of the atomic polarization to 5\% would be helpful for $\beta^{+}$-decay experiments. [Preview Abstract] |
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3A.00029: A Pyroelectric Crystal Particle Accelerator Amanda Gehring, Rand Watson Recent experiments have shown that the electric field produced by heating or cooling a pyroelectric crystal can be utilized to accelerate deuterons to sufficient energies to initiate the d + d fusion reaction., which suggests the possibility of developing a pyroelectric crystal neutron generator. The objective of this project was to investigate parameters that determine the energy and intensity of the particle beam with the final goal of maximizing the neutron output. A lithium tantalate pyroelectric crystal and two 25 W resistors were mounted on a copper block. An external power supply was connected to the resistors. Upon heating, the front face of the crystal becomes positively charged, creating positive ions from field ionization of nearby gas molecules. The positive ions are accelerated toward the target, and electrons from the target are accelerated toward the crystal where they collide, producing x rays and bremsstrahlung. Resulting spectra are measured with a Si(Li) detector, and the endpoint of the bremsstrahlung is used to determine the accelerating potential. Upon cooling, the polarity reverses. Heating cycles at different heating currents were observed, and the highest potential (88 kV) and intensity were achieved at 2.0 A. Next, a deuterated polyethylene target, deuterium gas, and a liquid scintillator neutron detector were added to the system. Runs were carried out at gas pressures ranging from 5x10$^{-3}$ to 1x10$^{-4}$ Torr, but the observed neutron counting rates were never above the background rate. [Preview Abstract] |
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3A.00030: Hadron Fiducial Cuts for the CLAS E5 Data Kristen Greenholt, Gerard Gilfoyle We have developed selection cuts for positively-charged hadrons from the $D(\vec e,e^\prime p)n$ reaction in the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. CLAS measures the scattering of electron and photon beams on nuclear targets and is a large, complex, particle detector. For accurate measurements we select data from regions of CLAS where its response is well understood and not changing quickly. We use fiducial cuts to define the regions of CLAS where the azimuthal dependence of positive hadrons is constant. First, a trapezoidal function is fitted to this azimuthal dependence in a particular scattering angle and momentum bin of a proton or positive pion. Next, the limits of the trapezoid's plateau are fitted as a function of the hadron scattering angle for each momentum bin. Last, the parameters of this second generation fit are, in turn, fitted as functions of hadron momentum to give us well-behaved functions defining the active region of CLAS. We will discuss the details of this method and apply it to the the electrodisintegration of the deuteron in the $D(\vec e,e^\prime p)n$ reaction. The data were collected at two beam energies, 2.6 GeV and 4.2 GeV. Different magnetic field polarities were used for the 2.6-GeV data to cover a broader $\rm Q^2$ range. [Preview Abstract] |
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3A.00031: Straggling Effects in the S800 Ion Chamber Joseph Grochowski, Brad Sherrill, Daniel Bazin A detailed investigation of the atomic number resolution of the S800 ion chamber has been performed. Accurate identification of the atomic number of ions resulting from nuclear reactions is essential to separate various reaction products. The main source of uncertainty in the identification of atomic number is energy loss straggling. Experimentally, energy straggling is an observed width of the energy loss distribution as ions traverse matter. To improve the resolution of ion identification, detector straggling must be minimized. First, the sources of straggling must be identified and quantified. An effort has been made to identify and minimize all source of error in the energy loss measurement. The most common source is energy loss straggling. This is the statistical variability in collisions, thus energy losses, as a large number of identical ions pass through matter. Charge exchange straggling is another potential source. This is described as the tendency of an incoming ion to capture a number of electrons, influencing its range through matter. Contributions from the finite momentum acceptance of the S800 and electronic noise were also evaluated. Details of the analysis and techniques to improve the atomic number resolution will be presented. [Preview Abstract] |
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3A.00032: Parton Momentum Distribution of the $\Lambda$ Stephanie Harp, Tom Shelly In the proton there exist valence quarks, two up and one down quark, as well as light flavor sea quarks: up, anti-up, down, anti-down; and gluons. Zhang et al. assumed a Fock state expansion for the proton and used the principal of detailed balance to find the probability of each state. They assumed that there are three types of transitions; a quark can split into a quark and a gluon, a gluon can split into a quark anti-quark pair and lastly a gluon can split into two gluons. In this model, the numbers of light flavor sea quarks were found to be asymmetrical (dbar-ubar $\ne $ 0), in agreement with experiment. We extend this model to the Lambda particle, the lightest strange baryon. The Lambda particle has three valence quarks: an up quark, a down quark and a strange quark. We calculate parton distributions for the Lambda, and find a symmetric light sea. Using the assumption of detailed balance of Zhang et al. and a Monte-Carlo calculation, we find the momentum distribution of the partons in the Lambda. [Preview Abstract] |
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3A.00033: Calibration of the Thick and Thin Scintillators for the NSCL/FSU Sweeper Magnet System Anne Hayes The MoNA (Modular Neutron Array) Sweeper-magnet setup at the NSCL is designed to measure neutron unbound states by full kinematic reconstruction of the neutrons and the decay fragments. One crucial aspect of these coincidence experiments is the particle identification of the charged fragments in the focal plane detectors following the sweeper magnet. The particle ID is achieved by the measurement of the energy-loss and total kinetic energy in large thin and thick plastic scintillation detectors, respectively. The pulse-height of the signals from these detectors is strongly position dependent. In order to achieve accurate Delta-E/E-identification for the fragments it is thus necessary to correct for these position dependencies. A procedure was developed to implement this correction quickly and efficiently for the on-line analysis. The procedure is based on Tcl-scripts sourced in the analysis program SpecTcl in combination with fitting routines in Excel. The performance of this procedure will be presented with data from experiment 05124, which studied neutron unbound states close to the neutron dripline. [Preview Abstract] |
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3A.00034: Pion efficiency analysis for ALICE Transition Radiation Detector prototypes using an LQ-X method David Hernandez One goal of ALICE, the only dedicated heavy-ion experiment at CERN's Large Hadron Collider (LHC), is to study the elusive Quark-Gluon Plasma (QGP), using theoretically predicted changes in the production of particles. Original particles can be reconstructed via their decay electrons. The Transition Radiation Detector (TRD) detects transition radiation from ultrarelativistic electrons, facilitating electron/pion discrimination in momenta ranges above 1 GeV/c. In addition to an increased energy deposit, electrons differ from pions in time signatures, because the transition radiation photons are absorbed in the first instants. The pion rejection is analyzed for 2004 electron/pion beams of momenta 4 to 10 GeV/c, with 6 layers of the TRD, by calculating and combining the two signatures in what is called a bidimensional LQ-X method. Rejection factors increase by more than 10\% with respect to a standard energy deposit analysis. The effects on pion rejection of tail cancellations in the signals and amplification regions in the TRD are explored. [Preview Abstract] |
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3A.00035: Beam Transport Efficiencies of the LEBIT Cooler/Buncher Matthew Hodek, Georg Bollen, Stefan Shwarz, Amanda Prinke, Josh Savory The Low Energy Beam and Ion Trap (LEBIT) facility at the NSCL is used to make high precision mass measurements of rare isotopes. A continuous beam of fragments from the NSCL's Coupled Cyclotrons Facility is stopped in a gas cell and extracted as a continuous ion beam. These ions are then accumulated and cooled using a linear radio frequency quadrupole (RFQ) ion trap filled with a low pressure buffer gas. On command the ions are ejected as a low emittance bunch. This pulsed beam is then injected into a 9.4T Penning trap for mass measurement. The cooling and bunching of the isotopes is essential for an efficient capture in the Penning trap and for obtaining high mass precision. Presented here is a study of the transport efficiencies of the RFQ cooler and buncher of LEBIT. The role of unwanted 'parasitic' traps inside this cooler and buncher was investigated. For this purpose detailed SIMION simulations were performed. These simulation results are compared to the results of dedicated experimental tests. [Preview Abstract] |
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3A.00036: Coulomb Excitation of $^{49}$Cr Kelly Hosier, Darren McGlinchey, Lewis Riley We measured gamma rays in coincidence with $^{49}$Cr particles scattered from a $^{209}$Bi target with a mid-target beam energy of 58 MeV/u at the National Superconducting Cyclotron Laboratory. We used GEANT simulations to extract the probability of populating the 272 keV 7/2$^{-}$ state of $^{49}$Cr via Coulomb excitation. This result is compared with existing measurements and shell model calculations. [Preview Abstract] |
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3A.00037: Elemental Analysis using Pulsed Neutrons Eric Houchins, Phillip Womble, Alexander Barzilov, Jon Paschal, Ian Rice, Jeremy Board, Joeseph Howard Elemental analysis using pulsed fast neutrons is a method in which elemental compounds can be analyzed during neutron bombardment using a pulsed d-T neutron generator. The 14 MeV neutrons impinging upon a material create a plethora of nuclear reactions including (n,n'), (n,p), (n,$\gamma )$, etc. Each isotope has a specific gamma ray pattern which leads to isotope identification and the intensity of each gamma ray can determine the relative amount of that isotope. From the elemental densities, the threat potential can be discerned. We will discuss the methodology as well as a recent examination of 53 naval ordnance items found in Yorktown VA. [Preview Abstract] |
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3A.00038: Benchmarking of ORRUBA via the $^{124}$Sn(d,p)$^{125}$Sn reaction J.A. Howard, R.L. Kozub, S.D. Pain, J.A. Cizewski, R. Hatarik, J.S. Thomas, D.W. Bardayan, J.C. Blackmon, C.D. Nesaraja, K.Y. Chae, K.L. Jones, Z. Ma, A.L. Gaddis, M.S. Johnson, R.J. Livesay At the Holifield Radioactive Ion Beam Facility, high quality radioactive beams are employed for measurements of importance to nuclear structure and astrophysics. Transfer reactions, measured in inverse kinematics, yield information on the development of nuclear structure away from stability. The Oak Ridge Rutgers University Barrel Array (ORRUBA) is a silicon detector array being developed for use in such measurements, specifically for (d,p) reactions. The array provides a large solid angle coverage utilizing resistive strip detectors, providing high resolution in energy and position, with a channel count which can be instrumented using conventional electronics. Recently, a $^{124}$Sn stable beam was used, via the (d,p) reaction, to determine the performance of the array in experiments with nuclei in the A$\sim$132 region. Details of this test measurement, and the results obtained, will be presented. [Preview Abstract] |
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3A.00039: Fiducial Cuts for the CLAS G3 Data Set Elliot Imler, Richard Bonventre, Christian Shultz, Michael Vineyard Fiducial cuts have been determined for protons and charged pions produced by photons with energies between 0.3 and 1.5 GeV incident on Helium targets in the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. This work is part of a systematic study of neutral meson photoproduction from the proton and light nuclear targets to investigate nuclear medium modifications of nucleon resonances and the meson-nucleon interaction. The fiducial cuts are performed to eliminate data from regions of the detector with non-uniform acceptance. The cuts were determined by fitting a trapezoidal function to the $\phi$ spectra binned in scattering angle and momentum for each particle type. The $\phi$ position of the corners of the trapezoids were then fitted as a function of scattering angle, and the parameters of these fits were fitted as a function of momentum to obtain the functions that are applied to the data to produce the cuts. The procedure will be described and the results will be presented. [Preview Abstract] |
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3A.00040: Integration constraints on a future high Pt muon trigger for PHENIX at RHIC Daniel Jumper The PHENIX experiment is a large-scale, complex detector system stationed at the RHIC accelerator ring. One of PHENIX's goals is to understand the long obscured contributing factors of the protons' spin structure. This is accomplished by studying the muon decay of W bosons produced by quark-anti quark interaction in polarized proton-proton collisions. A trigger upgrade of Resistive Plate Chambers (RPCs), currently funded for PHENIX, will significantly enhance the ability to trigger on muons at high Pt, where they are more prevalent than other signal sources. By triggering in this manner, the rejection factor of undesired sources is greatly increased, bringing the previously unmanageable rate of data acquisition within practical ranges. The RPCs, however, fall under serious design limitations due to integration constraints of experiment complexity leaving extremely limited space for the chambers, their support systems, and installation. Although these restrictions are far from trivial, careful designs and integration plans have been implemented that overcome them and will bring this spin study to a practical reality. [Preview Abstract] |
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3A.00041: Test of the Optical Readout of the UConn TPC Detector Tristan Kading, Moshe Gai, Kai Tittlemeier, Volker Dangendorf The UConn Time Projection Chamber (TPC) detector is being constructed as a UConn-Yale-Weizmann-PTB-TUNL-LLN collaboration to measure at the HI$\gamma $S at TUNL the $^{16}$O($\gamma $,$\alpha )^{12}$C reaction of importance for stellar evolution theory. We are currently constructing the readout system of this TPC using the optical chain of the CERN-CHORUS neutrino experiment. The Contrast Transfer Function (CTF) across the entire chain was measured at the Lab at PTB, Braunschweig, Germany, using a CCD camera and it was found be sufficient (sub-millimeter resolution) for resolving the expected tracks of particles in the TPC. Results of this measurement will be presented. [Preview Abstract] |
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3A.00042: Design, Construction, and Operation of a Small-Scale Radioactivity Assay Chamber Wesley Ketchum, J.A. Detwiler, P.J. Doe, R.A. Johnson, M.G. Marino, A.S. Reddy, A.G. Schubert, B.A. VanDevender, J.F. Wilkerson The ability to limit background signals from naturally occurring and cosmic ray induced radioactive materials is often essential for many nuclear physics experiments. Projects investigating the nature of neutrinos, such as the tritium single-beta decay experiment KATRIN and the neutrinoless double-beta decay experiment Majorana, require very low levels of backgrounds noise in order to succeed. To test the radioactivity of materials that may be used in these experiments, we have designed, constructed, and operated a small-scale low-background radiometric assay chamber at the University of Washington, CENPA. This chamber consists of two high-purity germanium detectors enclosed in both active and passive shields. We present early results showing energy calibrations, efficiency calculations for known sources, and the effectiveness of a lead shield and cosmic veto at reducing background radiation from the environment and the resulting increase in sensitivity to radioactive impurities. With the aid of computer simulations, we hope to be able to maximize this sensitivity by optimizing the detector geometry, shield, and cosmic veto design. [Preview Abstract] |
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3A.00043: Search for Triaxial Superdeformed Bands in $^{174}$W Andrew Knox Nuclei at high angular momentum occasionally stabilize in elongated ellipsoidal shapes, and, more rarely, in triaxial superdeformed shapes. Rotation of superdeformed nuclei leads to long sequences of regularly spaced gamma-ray transitions between successive states. Transitions from the sparsely populated superdeformed bands to normal deformed states are extremely weak due to the large difference in their wavefunctions. The approximately regular nature of a superdeformed band and strong intra-band gamma-ray coincidences allows a systematic grid search of coincidence data to identify such bands. A grid search was performed for theoretically predicted triaxial superdeformed bands in $^{174}$W by inspecting three- and four-fold coincidence data. High spin states in $^{174}$W were populated using a 225 MeV $^{50}$Ti beam from the ATLAS accelerator at Argonne National Laboratory incident on a thin $^{128}$Te target. The gamma-rays were detected using the Gammasphere array. [Preview Abstract] |
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3A.00044: g-Factors in 94Zr D.A. Kovacheva, C.A. Copos V.Werner2, P. Boutachkov3, E. Stefanova3, N. Benczer-Koller3, G. Kumbartzki3, N. Pietralla4, M. Perry5, M. Fetea1, H. Ai2, R.B. Cakirli2, 6, R.F. Casten2, M. Chamberlain2, 7, C.R. Fitzpatick2, 7, A.B. Garnsworthy2, 7, G. Gurdal2, 8, A. Heinz2, X.Liang2, 9, P. Maier-Komor10, E.A. McCutchan2, D.A. Meyer2, J. Qian2, K.-H. Speindel11, A.E. Stuchbery12, N.J. Thompson2, 7, E. Williams2, R. Winkler2, K. Aleksandrova1, G. Anderson1, B. Darakchieva1, M. Evtimova1, P. Manchev1, J.P. Greene2, C. Lambie-Hanson2. 1 U. of Richmond, 2 WNSL, Yale, 3 Rutgers University, 4 Universitat zu Koln, DE, 5 Florida State University, 6 Istanbul University, TR, 7 U. of Surrey, UK, 8 Clark University, 9 U. of Paisley, UK, 10 Technische Universitat Munchen, DE, 11 Universitat Bonn, DE, 12 Australian National University --- An experiment was performed to investigate the p-n configurations in symmetric and mixed-symmetric low-lying states, in 94Zr. A precession nuclear measurement was used to deduce g-factors. The 94Zr was accelerated at WNSL to 275 MeV with intensities of 1pnA. The 94Zr isotope was Coulomb excited in the C layer and exposed to a strong transient magnetic field in the Gd layer of the multilayered target. Gamma rays were detected in coincidence with the forward-scattered C in either of four clover Ge detectors. Preliminary results on anisotropy ratios of intensities at two angles will be presented [Preview Abstract] |
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3A.00045: Coulomb Excitation of $^{46}$V and Testing Isospin Symmetry in the $A=46$, $T=1$ Multiplet J.W. Kremenak, D.C. McGlinchey, L.A. Riley A beam of the rare isotope $^{46}$V was studied via intermediate energy Coulomb excitation at 60 MeV/nucleon at the National Superconducting Cyclotron Laboratory (NSCL). The $B(E2;0^{+}_{g.s.}\rightarrow 2^{+}_1)$ value of $^{46}$V was used to calculate the M$_{o}$ value for the nucleus. The extracted M$_{o}$ value in $^{46}$V was compared with the isoscalar multipole matrix element extracted from the previously determined $B(E2;0^{+}_{g.s.}\rightarrow 2^{+}_1)$ values of $^{46}$Cr and $^{46}$Ti. Preliminary results will be presented. [Preview Abstract] |
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3A.00046: A New Measurement of the Muon Lifetime with the MuLan Experiment Josh Kunkle Following recent theoretical calculations, the uncertainty on the Fermi coupling constant is now limited by the precision with which the muon lifetime is measured. The current world average uncertainty on the lifetime is 17~ppm. The MuLan experiment is designed to measure the muon lifetime to 1~ppm. To supply muons, a periodic, pulsed muon beam is created. During a $5~\mu$s ``fill period'', muons are directed to a thin stopping target. A $22~\mu$s ``measurement period'' follows with the beam ``off'' while the stopped muons decay. A spherical detector surrounding the target detects the decay positrons. A wire chamber with a $10 \times 10$~cm window is used during beam tuning and for regular measurements during data production. An FPGA is used to enable fast readout of the wire chamber. The firmware that controls the FPGA allows for prescaling during the fill period to reduce the data rate. A number of scalar signals are produced that reflect the flux of muons in specific areas of the chamber. This firmware is currently being used in the 2006 data production run. I have been responsible for the FPGA firmware, as well as various analysis studies. [Preview Abstract] |
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3A.00047: Investigation of 0$^{+}$ States in the Transitional Nucleus $^{108}$Pd Christopher Lambie-Hanson, R. Winkler, A. Heinz, R.F. Casten, J. Qian, R. Kruecken, T. Faestermann, H.F. Wirth, R. Graeger, S. Christen A (p,t) reaction on a $^{110}$Pd target at the MLL (Maier-Leibnitz Laboratory at LMU and TU Munich) MP tandem accelerator laboratory was used to populate excited 0$^{+}$ states of $^{108}$Pd, which lies in the transitional region between spherical and deformed nuclei. A Q3D spectrometer separated the components of the reaction products according to their energies. The angular distributions of the population cross sections of excited states along with their relative energies were used to assign spin, parity, and excitation energy. The unique shape of the angular distributions of 0$^{+}$ states allowed the identification of both previously known and previously unknown 0$^{+}$ states in $^{108}$Pd at and below the excitation energy of 3.5 MeV. The study of these excited states will lead to a greater understanding of collective behavior and nuclear deformation. This experiment extends previous research into the nature of 0$^{+}$ excitations in deformed and transitional nuclei in the rare earth region to a transitional nucleus of lower mass. Experimental results and details of data analysis will be presented. This work was supported by DOE Grant DE-FG02-91ER-40609. [Preview Abstract] |
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3A.00048: Measurements of $^{11}B(\vec{p},p)^{11}B$. Thomas Lewis, Ralph France III, AJ Richards, Mohammad Ahmed, Matthew Blackston, Seth Henshaw, Paul Kingsbury, Brent Perdue, Henry Weller, Richard Prior, Mark Spraker The vector analyzing powers, $A_y(\theta,E)$, of the $^{11}B(\vec{p},p)^{11}B$ reaction were measured as a function of angle and energy as part of a program to study the reaction $^{11}B(p,\alpha)2\alpha$. The experiment was performed at the Triangle Universities Nuclear Laboratory at Duke University, where polarized proton beams between 100 nA and 600 nA with energies ($E_p$) of 1.388, 2.65, 3.9, 4.0, 4.93, 5.11, and 5.5 MeV were produced using the ABPIS source and the FN tandem. These energies were selected to be on (and off) several of the known resonances in this region. The target was composed of $35\ \mu g/cm^2$ isotopically pure (99.9\% enriched) $^{11}B$ deposited on a $9\ \mu g/cm^2$ carbon backing. Scattered protons were detected by an array of six surface barrier detectors placed symmetrically to the left and right of the target. The analyzing powers will be used to further our understanding of the reaction dynamics of the elastic proton channel in this energy region. [Preview Abstract] |
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3A.00049: Describing Nuclei on the Alhassid-Whelen Arc of Regularity in a SU(3) Basis P. Manchev, M.S. Fetea, R.F. Casten, S. Eckel Until fairly recently, it was thought that most nuclei lie on or near the perimeter of the Casten triangle. It is now known this is not the case; in fact, most nuclei inhabit the interior of the Casten triangle. More than a decade ago Alhassid and Whelen discovered a striking benchmark. They identified an interior path connecting the U(5) and SU(3) vertices of the Casten triangle which unlike most of the rest of the interior does not exhibit chaos but rather preserves regularity. Jolie et al. [1] found 12 nuclei whose parameters lie along this regularity. They also identified an almost one-to-one correspondence between the near degeneracy of the $\gamma $ band head and the K=0$_{2}^{+}$ band head for those nuclei. Most of the calculations involving the IBA are done in a U(5) basis. Wave functions of the nuclei on the arc of regularity are complicated when expressed in a U(5) basis but may be easier to work with in a SU(3) basis. Our goal is to determine features of nuclei on or close to the Arc based on the SU(3) description of their wave functions. Preliminary results will be presented. References: [1] J. Jolie et al., Phys. Rev. Lett. 93, 132501 (2004). [Preview Abstract] |
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3A.00050: Systematics of Giant Electric Dipole Resonances in Hot, Rotating Nuclei Katherine McAlpine, Andreas Schiller, Michael Thoennessen The dependence of hot Giant Dipole Resonance (GDR) widths on spin, temperature, and mass is an exciting field of study. In 2001, Kusnezov et al.\ [1] developed a scaling law to predict the width as a function of these parameters. The law is a reliable description of their data set. Recently, Schiller and Thoennessen [2] prepared a compilation of GDR parameters built on excited states. The scaling law is tested over this larger data set, about five times the number of entries utilized by Kusnezov. Beyond a more detailed study of the dependence of the width on temperature and spin, the compiled data can be broken into subsets with common characteristics. By analyzing subsets of the data, we hope to gain a clearer understanding of the influence of shell effects, deformation, and gating conditions on the GDR width.\\[0mm] [1] D. Kusnezov et al., Phys.\ Rev.\ Lett.\ \bf 81\rm, 542 (1998).\\[0mm] [2] A. Schiller and M. Thoennessen, nucl-ex/0605004. [Preview Abstract] |
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3A.00051: Monte Carlo Simulation of New UCN Source at LENS Patrick McChesney My research has focused on a Monte Carlo study of a new ultracold neutron (UCN) source under development at the Low Energy Neutron Source (LENS) at the Indiana University Cyclotron Facility. UCNs are neutrons with energies below $3 \times 10^{-7}$ eV. They can be used to make extremely accurate measurements of the electric dipole moment of the neutron to test time reversal symmetry. LENS has successfully produced cold neutrons and we are designing an extension to study UCN production. I have modeled a UCN module which will test a novel technique involving magnon interactions in solid oxygen to produce UCNs. Our module slows down the fast neutrons produced by a (p,n) reaction in Be target with a polyethylene cold neutron moderator and directs the resulting cold neutrons into a half liter piece of solid oxygen with water and polyethylene as reflectors. Cold neutrons enter into solid oxygen and are down-scattered to the UCN energy range. These UCNs are then directed upwards toward a storage bottle at a higher elevation, being further slowed down by gravity. I have tested various design configurations trying to maximize the cold neutron flux through the solid oxygen component while minimizing the heat load in the cryogenic system. The simulations predict a cold neutron flux of $2 \times 10^{10}$ $n/cm^{2}/s$ with a heat load around 1 W from 2.5 mA of 13 MeV protons. My findings are being used as a guideline to design our module. [Preview Abstract] |
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3A.00052: Geant4 Simulations of Gamma Ray Detectors D.C. McGlinchey The Geant4 toolkit is used to develop simulations of the Segmented Germanium Array (SeGA) at the National Superconducting Cyclotron Laboratory (NSCL). A simple NaI detector is used as a starting example in order to test the Geant4 toolkit. Simulated spectra were compared with measured spectra from $^{137}$Cs, $^{133}$Ba, $^{22}$Na, and $^{60}$Co. It has been found that the lineshape of the simulated spectrum matches well with the lineshape of the collected spectrum within the tested energy range of 0-1400 keV. A similar comparison of source data from a single SeGA detector has been made and results will be presented. [Preview Abstract] |
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3A.00053: The Utilization of Free-Running Digital Signal Processors as a Method of Multi-channel Analysis Chris McGrath, Matthew Nichols, Phillip Womble, Alex Barzilov, Ivan Novikov, Jeremy Board, John Paschal A new generation of neutron-based explosives detection systems is beginning to be built. However, these systems are handicapped by low through-put data acquisition systems. We are developing a faster data acquisition system using a continuously digitizing (``free running'') analog to digital converter. In our method, the incoming electrical signals are processed directly from the anode output of the voltage divider chain on the photo-multiplier tube. The shape and duration of the waveform to be analyzed is strongly dependent on the time constants of the RC components in the last stages of the voltage divider chain. The rise times of these signals are typically less than one hundred ns and their fall times are much longer ($>$5 $\mu $s). Signal filters and signal amplitudes are calculated from the digital data stream without any front-end analog electronics. In addition, signals which normally would be rejected during high-counting rates because of ``pile-up'' conditions can be recovered under certain circumstances. This will allow the faster investigation times and reduce risk to personnel and the public. A potential spin-off application is the utilization of these electronics in medical imaging such as PET scanning. [Preview Abstract] |
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3A.00054: Investigating $\phi(1020)$ mesons from photo- and electro-production on nuclear targets with the CLAS detector. Will Morrison, Maurik Holtrop The data sets from two large experiments with the CLAS detector at Jefferson Laboratory were used to look for the $\phi(1020)$ meson in photo-production on deuterium and in electro-production on $^{2}$H, $^{12}$C and $^{56}$Fe. The $\phi$ mesons were identified by their decay to a $K^{+}$ $K^{-}$ pair. We investigate the possibility of extracting nuclear transparency ratios from this data and discuss implications for future experiments with an upgraded CLAS detector. The experimental setup, the data analysis technique and some preliminary results will be presented. [Preview Abstract] |
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3A.00055: Cosmic Muon Flux Variations Using the Modular Neutron Array Evan Mosby, Shea Mosby, Jamie Gillette, Malinda Reese, Warren F. Rogers We've developed an acquisition and analysis package for the Modular Neutron Array (MoNA), located at the National Superconducting Cyclotron Laboratory (NSCL), for offline monitoring of angular and temporal variations of cosmic muon flux in the sky. The Cosmic Muon Detector Array (CMDA), a device developed by undergraduate students at Westmont College, was modeled after MoNA for use in cosmic muon flux measurements. Much of the analysis routines for the CMDA were adapted for use in MoNA. Because of MoNA's larger and more numerous detectors, it is capable of gathering much better statistics in shorter time compared with the CMDA. The top and bottom layers of MoNA are used to optically image the muon distribution in the sky with the help Tcl scripts, which also apply optical corrections for angular efficiency of the array. Long term variations in cosmic flux anisotropies, as well as data binned into the 24 solar and sidereal hours are monitored, and compared with results from the CMDA. Results will be presented. [Preview Abstract] |
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3A.00056: Neutron Multiplicity Discrimination in MoNA Shea Mosby, Evan Mosby, Warren F. Rogers The Modular Neutron Array (MoNA) is a high efficiency neutron detector located at the National Superconducting Cyclotron Laboratory at Michigan State University and used in conjunction with the NSCL/FSU sweeper magnet to conduct coincidence experiments on unstable nuclei near the neutron drip-line. Experiments using this detector combination involve the loss of one or more neutrons from particle-unbound nuclei; it is therefore important to distinguish neutron multiplicity in MoNA in order to effectively analyze data from these experiments. We've developed an algorithm to distinguish neutron multiplicity based on the kinematic propagation properties of neutrons though MoNA. Scatter plots of neutron velocity, energy deposition, and scattering angle are constructed from which gates can be drawn for neutron multiplicity discrimination. Data from a few one- and two-neutron experiments have been analyzed, and results will be presented. [Preview Abstract] |
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3A.00057: A Gamma Ray Spectrometer Based on Mobile Phone Technology Kyle Moss, Alexander Barzilov, Phillip C. Womble, Jon Paschal We have developed a miniature spectrometer for gamma-ray detection and automatic isotope identification (RadPhone) which uses mobile phone technology to analyze the data and to distribute the results to security personnel. The RadPhone system consists of two modules, a detector module and wireless phone module. The detector module houses a detector, a small data acquisition system, Bluetooth transceiver, and power supply (battery). Using a Bluetooth channel, this module communicates to the Motorola$^{TM}$ MPx220 wireless phone with data acquisition and analysis software which serves as a data acquisition computer. RadPhone offers a small, portable means of gamma-ray detection and identification. [Preview Abstract] |
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3A.00058: Studies of nuclei around proton drip-line at the HRIBF Recoil Mass Spectrometer using a rotating target Clarke Nelson The investigations of nuclei around proton drip line allow us to verify nuclear structure models initially developed based on data obtained for the isotopes near a beta stability line. However, these exotic nuclei are very difficult to study, mainly because of very low production cross section. The fusion-evaporation reactions between heavy-ions and fragmentation of relativistic heavy-ions are preferred production methods for very proton rich nuclei. In both cases, the high intensity of primary beam helps to increase the amount of produced nuclei. This contribution analyses the yields of alpha and proton radioactivities produced in fusion-evaporation reactions and studied at the Recoil Mass Spectrometer at the Holifield Radioactive Ion Beam Facility (HRIBF). The recently commissioned rotating target device [1] allowing us a substantial increase in the primary beam current will be presented. In particular, the probability to reach doubly-magic nucleus $^{100}$Sn in so far unobserved superallowed alpha decay chain $^{108}$Xe$\rightarrow$$^{104}$Te$\rightarrow$$^{100}$Sn [2] will be discussed.\\ $[1]$ J.Johnson et al., HRIBF,Oak Ridge, 2006\\ $[2]$ S.Liddick et al., Phys. Rev. Letters, in press [Preview Abstract] |
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3A.00059: Single Particle Energies in Skyrme Hartree-Fock and Woods-Saxon Potentials Brian Newman Atomic nuclei exhibit the interesting phenomenon of single-particle motion that can be described within the mean field approximation for the many-body system. We have carried out Hartree-Fock calculations for a wide range of nuclei, using the Skyrme-type interactions. We have examined the resulting mean field potentials U$_{HF}$ by fitting r$^{2}$ U$_{HF}$ to r$^{2}$U$_{WS}$, where U$_{WS}$ is the commonly used Woods-Saxon potential. We consider, in particular, the asymmetry (x=(N-Z)/A) dependence in U$_{WS}$ and the spin-orbit splitting in the spectra of of $^{17}$F$_{8}$ and the recently measured spectra of $^{23}$F$_{14}$. Using U$_{WS}$, we obtained good agreement with experimental data. [Preview Abstract] |
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3A.00060: The Effect of Nuclear Cross-Section Data on the Measurement of Elemental Densities in Explosives Threat Analysis M.E. Nichols, P.C. Womble, A. Barzilov, E. Houchins, J.R. Moore, J. Board, J. Paschal, L. Hopper With the impending threat of terrorist attacks in the modern age, it is important to neutralize these threats as quickly and efficiently as possible. One critical means of doing this is to detect high explosives. Our research principally deals with the detection and quantification of the elements hydrogen, oxygen, nitrogen and carbon to differentiate between explosives and non-explosives and presents an effective means of detection via quantification of these elemental densities. Materials can be separated into innocuous and threat categories based on their elemental densities. For nuclear-based measurements, however, the nuclear cross-sections erode this segregation. We have been developing threat algorithms in which the nuclear cross-section has been coupled with the elemental density. [Preview Abstract] |
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3A.00061: Understanding the N*(1710) Resonance by Scanning the $\pi ^{-}p$ System in the (1610-1770) MeV Region Temitope Omiwade Abilene Christian University in collaboration with Petersburg Nuclear Physics Institute (PNPI) and Institute for Theoretical and Experimental Physics (ITEP) have been working to improve the pion-nucleon resonance by scanning of the $\pi ^{-}p$ system invariant mass in the (1610-1770) MeV region with the detection of $\pi ^{-}p$ and ${\rm K}\Lambda$ decays. Previous experiments indicate inconsistencies in the P$_{11}$(1710) resonance in the reaction $\pi ^{-}p \rightarrow \pi ^{-}p$, however, using the reaction $\pi ^{-}p \rightarrow {\rm K}\Lambda$, the nucleon resonance can be understood better. Using a GEANT4 simulation, we were able to model the particles from the target and retrieve information on these particles from the hodoscope. Using ROOT, a detailed analysis was retrieved from the data to differentiate between the protons and pions at the hodoscope. The goal of my work is to provide criteria for discrimination of proton from pion tracks in the final state using the TOF system. [Preview Abstract] |
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3A.00062: A Data Acquisition System for $\nu$-SNS Development S.V. Paulauskas, R.L. Kozub, J.C. Blackmon, D.W. Bardayan, Q. Zeng, Y.V. Efremenko, K. Scholberg, A. Crowell The $\nu$-SNS project at the Spallation Neutron Source aims to study neutrino-nucleus interactions important for understanding nuclear structure and astrophysics. Understanding the neutron background produced by the 1 GeV proton beam of the SNS is crucial to designing the shielding and detectors for $\nu$- SNS. To this end a facility is being constructed to study the neutron backgrounds at the SNS. In order to process data from scintillation detectors a LabVIEW\footnotemark[1] program was written. This program communicates with CAMAC based ADC modules via a GPIB crate controller and a USB interface. Three of the ADCs receive gates to store information from different time intervals for neutron-gamma discrimination. The fourth ADC stores TAC signals with neutron TOF information. The LabVIEW\footnotemark[1] program creates spectra that can be used to identify neutrons and gamma rays. Measurements with neutron and gamma sources were performed to study the effectiveness of different techniques of neutron-gamma discrimination. \footnotetext[1]{LabVIEW is a trademark of National Instruments Corporation.} [Preview Abstract] |
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3A.00063: p-n configurations of symmetric and mixed-symmetric states M. Perry, V. Werner, N. Pietralla, N. Benczer-Koller The first $2^+$ state in collective even-even nuclei is a proton-neutron (pn) symmetric quadrupole excitation. It has a mixed-symmetric counterpart, which has p-n anti-symmetric parts in the wavefunction. A strong p-n interaction mixes the proton and neutron configuration, creating a low-lying symmetric state and a higher-lying mixed-symmetric state. The significant energy difference between the proton and neutron j=2 configurations and rather weak mixing between the proton and neutron state wavefunctions in Zr isotopes results in a $2^+_1$ state with neutron dominance and a $2^+_2$ state with proton dominance, which was identified as the one-phonon mixed-symmetry $2^+$ state. This signature in Zr provides an ideal basis for studying configuration mixing. This mixing is studied experimentally by measuring g factors. Theoretical predictions will be compared with recent experimental results. [Preview Abstract] |
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3A.00064: The Beta Cage: Screening Low Radioactive Backgrounds K. Poinar, D. Akerib, D. Grant, R. Schnee, T. Shutt, S. Golwala, Z. Ahmed The beta cage is a proposed multi-wire proportional chamber that will be the most sensitive device available to screen low-energy (200 keV) betas emitted at rates as low as $10^{-5}$ counts $keV^{1}$ $cm^{-2}$ $day^{-1}$ (of order $10^{-4}$ Bq/$m^{2}$). The expected sensitivity and details of the construction and commissioning of its prototype chamber are presented. The prototype beta cage is a 50x50x25 cm frame gridded by stacked wire planes contained in a chamber of gas. To reduce background, the chamber contains only enough mass to stop betas of interest. Samples are placed beneath the grid; the wires multiply the betas and collect their electron avalanche. Readouts allow discrimination of its events from background and determination of the beta (or alpha) source. The beta cage has potential use in carbon or tritium dating, with $^{3}$H/$^{1}$H sensitivity of $10^{-20}$ and $^ {14}$C/ $^{12}$C sensitivity of $10^{-18}$. Its design was motivated by CDMS, whose sensitivity to the dark matter candidate WIMPs is currently limited by low-energy beta contamination. [Preview Abstract] |
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3A.00065: Hold-up Time Measurements for Various Actinide Targets Emily Prettyman, H.K. Carter, Andreas Kronenberg, Eugene Spejewski, Daniel Stracener At Oak Ridge National Laboratory the Holifield Radioactive Ion Beam Facility produces radioactive ion beams (RIBs) by proton-induced fission on an actinide target. The RIB yields depend on the chemical and physical properties of the target used. The rates at which chemical elements are released from the target ion source, called hold-up times, can give information about the movement of chemical elements within the target material. This information may be useful in designing optimal targets to maximize production of specific isotopes. Hold-up times are measured using the UNISOR isotope separator, connected to the tandem accelerator. The proton beam is turned on until the element of interest reaches equilibrium between production and release. It is then turned off and the decrease of the release is observed. The current analysis was done by fitting the data with two exponential decay functions and the trend is hold-up times decrease as target temperature increases. Another attempt to fit the data would be to use equations that take into account diffusion and effusion with the goal of determining the ratios of the processes to see which dominates. The results will be presented. [Preview Abstract] |
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3A.00066: Detector resolution in the ``EPECUR'' project. Aldo Raeliarijaona In order to study the N*(1710) in the ``EPECUR'' project, the hodoscopes were put at some reasonable distance. This resolved the triggering problem since within a 10 cm strip-horizontally as well as vertically- there are 4 times less of double hit from one event than a single hit, there are also negligible multiple (3 or 4) hit providing from the collision ïÎp the decays K\r{ } to ïÎï+ and $\Lambda $\r{ } to ïÎp. [Preview Abstract] |
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3A.00067: Determining the Feasibility and Precision of an On-Site Radioactivity Test Chamber A.S. Reddy, J.A. Detwiler, P.J. Doe, R.A. Johnson, Wesley Ketchum, M.G. Marino, A.G. Schubert, B.A. VanDevender, J.F. Wilkerson Backgrounds are a limiting factor to the sensitivity of many high precision nuclear physics experiments. Lowering these backgrounds is essential to experiments like Majorana and KATRIN, which look at neutrinoless double beta-decay and tritium beta-decay respectively. These backgrounds could be significantly reduced by using materials with low radioactivity. In order to aid these experiments in lowering backgrounds, we performed simulations to assess the feasibility and sensitivity with which an in-house radioactivity test chamber could be operated. Simulations were done in parallel with initial tests of the system. The system consists of two Ortec high purity germanium detectors housed in a lead chamber, which is shielded by scintillators used to determine cosmic coincidence. The programming utilized the Geant4 monte carlo toolkit, and analysis was done using ROOT. Simulations of calibration sources were compared with data in terms of spectral shape and overall normalization. The efficiency of the system was explored as a function of energy, detector orientation, and sample geometry. Simulations of the lead shielding and cosmic veto coverage were also done. [Preview Abstract] |
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3A.00068: Measurements of $^{11}B(\vec{p},\alpha)^8Be$ A.J. Richards, Henry Weller, Mohammed Ahmed, Matthew Blackston, Seth Henshaw, P. Kingsbury, Brent Perdue, Ralph France, Tom Lewis, Richard Prior, M. Spraker The vector analyzing powers of the $^{11}B(\vec{p},\alpha)^{8}Be_{g.s.}$ reaction were measured as a function of energy and angle as part of a program to study the $^{11}B(p,\alpha)2\alpha$ reaction at low energies. Polarized proton beams were produced by the ABPIS source and accelerated through the FN tandem at the Triangle Universities Nuclear Laboratory. The target was composed of $35\ \mu g/cm^2$ of isotopically enriched $^{11}B$ deposited on a $9\ \mu g/cm^2$ carbon backing. Emitted $\alpha$-particles were detected in an array of six surface-barrier detectors placed symmetrically to the left and right of the target. Measured asymmetries in scattering from the carbon backing were used to calibrate the beam polarization. Beams of 100 nA to 600 nA were used at energies of $E_p = 1.388$ MeV, 2.65 MeV, 3.9 MeV, 4.0 MeV, 4.93 MeV, 5.11 MeV and 5.5 MeV. An aluminum degrader foil was used to produce 575 keV through 775 keV beams (3 to 6 nA) to study the 675 keV resonance. These data will be used to develop a detailed understanding of the on- and off-resonance nature of this reaction. [Preview Abstract] |
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3A.00069: Analysis of the 11B(d,n)12C Reaction Nathan Ridling, Richard Prior, Mark Spraker, Henry Weller, Brent Perdue Studies have been performed on the \begin{math} ^{11}B(d,n)^{12}C \end{math} reaction to measure the absolute astrophysical S factor and its energy dependence, the reaction cross section, and tensor and vector analyzing powers \begin{math} T_{20}, T_{21}, T_{22}, \end{math} and \begin{math} iT_{11} \end{math}. The motivation behind this research project is not only its relevance to nuclear astrophysics, but also in the reaction dynamics of (d,n) reactions at very low energies. PSD (Pulse shape discrimination) was used along with PAW (Physics Analysis Workstation) in order to extract the neutrons from the gamma-rays. Using a neutron response function fitting routine in Root, we have determined the number of neutron counts leading to the ground and first excited states of \begin{math} ^{12}C. \end{math} These yields were used to construct the angular distributions of the cross section and analyzing powers. Ultimately, we will extract the reaction specific transition matrix elements. [Preview Abstract] |
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3A.00070: Application of THGEM to XENON Dark Matter Search Daniel Rubin Thick GEM-like (THGEM) multipliers made from copper-clad Cirlex (rather than the typical g10) were studied, with the goal of finding a low-background GEM that could be used in the XENON detectors. The Cirlex THGEMs were made with particularly large (1.0 mm) holes, in the hope that gain reduction due to xenon condensation in the holes could be avoided. Such THGEMs were found to have very high resistances (in the 10 TeraOhm range) in air, and gain curves similar to those of g10 THGEMs of the same thickness in a mixture of carbon dioxide and nitrogen at 75 torr. However, the THGEMs were found to spark easily, and had an inconsistent energy resolution. Both problems can be attributed to flaws in the drilling and etching of the THGEMs, which were found by visual inspection using a microscope. With some improvement in the manufacturing, Cirlex THGEMs should make an excellent addition to liquid xenon detectors. [Preview Abstract] |
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3A.00071: Using the Neutron-Deuteron Breakup Reaction as a Probe for the Three-Nucleon Force Kirby Runyon, Steven Wallace, Alexander Lipnicki, Mark Yuly An experiment is being performed at the Los Alamos Neutron Science Center to probe for a three-nucleon component (3NF) of the strong force. Historically, the strong force has been modeled as a two-nucleon interaction, but experimental evidence suggests interactions between nucleon triplets may contribute to the strong force. Neutrons with energies up to 800 MeV will strike a liquid deuterium target. Deuterium usage allows detection of the 3NF using the smallest possible nuclei since interactions will involve three nucleons. A magnetic spectrometer will measure scattered proton momenta and large plastic scintillators will detect neutrons. Neutron-proton elastic scattering will also be detected at conjugate angles for calibration purposes. Data collection is anticipated in October 2006. [Preview Abstract] |
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3A.00072: Lifetime Measurements and Deformation in $^{79}$Sr Y.K. Ryu, R.A. Kaye, S.R. Arora, S.L. Tabor, T. Baldwin, D.B. Campbell, C. Chandler, M.W. Cooper, C.R. Hoffman, J. Pavan, M. Wiedeking, J. D\"oring, Y. Sun, S.M. Gerbick, O. Grubor-Urosevic, L.A. Riley High-spin states in $^{79}$Sr were produced following the $^{54}$Fe($^{28}$Si, $2pn$) fusion-evaporation reaction using a beam energy of 90 MeV at the Florida State University (FSU) Tandem-Linac facility, and the resulting de-exciting $\gamma$ rays were detected with the FSU Ge array of 10 Compton-suppressed detectors. The $^{54}$Fe target was thick enough so that all of the synthesized nuclei could stop completely in the target, resulting in Doppler-shifted $\gamma$-ray line shapes that could be analyzed using the Doppler-shift attenuation method. In all, 23 lifetimes were measured in three separate band structures using this method, and then used to infer transition quadrupole moments ($Q_t$) and quadrupole deformations ($\beta_2$) using the rotational model. The results show good qualitative agreement with the predictions of both cranked Woods-Saxon (CWS) and projected shell model (PSM) calculations. The band based on a $d_{5/2}$ single-particle orbit, verified in this study through $\gamma - \gamma$ coincidences, intensity measurements, and directional correlation of oriented nuclei (DCO) ratios, was found to have the largest average deformation ($\beta _{2,ave} = 0.41$) among the three bands, in agreement with the CWS and PSM predictions. Supported in part by the NSF and the OWU SSRP. [Preview Abstract] |
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3A.00073: Astrophysical S(E)-factor of the $^{15}$N(p,$\alpha )^{12}$C reaction at sub-Coulomb energies via the Trojan-horse method Daniel Schmidt, M. La Cognata, S. Romano, C. Spitaleri, S. Cherubini, V. Crucilla, L. Lamia, R. Pizzone, A. Tumino, R. Tribble, L. Trache, Changbo Fu, V. Goldberg, A. Mukhamedzhanov, G. Tabacaru, S. Typel, B. Irgaziev The low-energy bare-nucleus cross section for $^{15}$N(p,$\alpha )^{12}$C is extended by means of the Trojan-horse method applied to the $^{2}$H($^{15}$N,$\alpha ^{12}$C)n reaction at E$_{beam}$=60 MeV. The astrophysical S-factor is compared to the direct data in the same energy region. A fair agreement is found at low energies between 80 keV and 250 keV, while the low-energy behavior of the S-factor suggests a smaller rate than reported in literature. There is a larger discrepancy between the direct data and Trojan-horse data at high energy. Further study is needed to clarify the source of this error. [Preview Abstract] |
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3A.00074: Excited State Lifetime Measurements in 96Mo using the GRID Method. A. Schmidt, V. Werner, J. Jolie, H. Borner, M. Jentschel, P. Mutti The Gamma-Ray Induced Doppler-broadening (GRID) [1] method was used to find lifetimes of excited states in 96Mo. A Mo target was placed close to the reactor core. Energies of gamma-rays emitted after neutron capture (n, gamma) were detected with ultra-high resolution using the double diffractometer GAMS- 4. By analyzing the Doppler-broadening of the spectral peaks of interest, lifetimes in the order of 100 fs to a few ps were determined. The short lifetime of the 2095 keV state, in the order of 100 fs, as well as its energy, make it the best candidate for the mixed-symmetric one-phonon state, which has been observed at similar energy in 94Mo. [1] H. G. Borner and J. Jolie, J. Phys. G 19, 217 (1993) [Preview Abstract] |
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3A.00075: Separating the Z$^{0}$ from Heavy Quark Background in Relativistic Heavy Ion Collisions Lewis Sharpnack The Compact Muon Solenoid at the Large Hadron Collider (LHC) is scheduled to begin experimental operations in late 2007. At full power, Pb-Pb collisions at LHC will produce quark gluon plasma (QGP), as well as numerous particle jets. In order to determine the energies of these jets, Z$^{0}$ bosons coming out of the plasma on the opposite side of the jet are examined. Direct observation of the Z$^{0}$ particle is impossible because it decays before reaching the detectors. It is possible to measure the decay products of the Z$^{0}$ to reconstruct the particle's energy prior to exiting the QGP. Some of the most useful decay products of the Z$^{0}$ to study are dimuons produced as a particle antiparticle pair. Dimuons are also copiously produced from decays of other particles, most notably, decays of D and B mesons originating from heavy quark pairs. These false Z0s constitute the background for experiments. Using various simulations, the dimuon signals from the Z$^{0}$ decays and the D and B decays have been modeled. Based on the simulated data, a series of limits on accepted values for such physical quantities as opening angle and decay momentum asymmetry have been established to maximize the signal to background ratio for Z$^{0}$ particles in the detector. [Preview Abstract] |
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3A.00076: Parton Distributions in the K$^{+}$ meson Thomas Shelly, Stephanie Harp The statistical model of [1] is extended to calculate the parton distributions in the K$^{+}$ meson (Kaon). The Kaon is the lightest particle containing a strange quark. It consists of two valence quarks (u and sbar) and a sea of other partons (quarks and gluons) that may be found inside the Kaon at any time. Here, the K$^{+}$ meson is represented as a superposition of states that contain a definite number of partons, known as Fock states. Using the method of [1], the probability of finding the Kaon in any given Fock state is calculated. From these results the average number of each type of parton in the Kaon is calculated. Asymmetry is found in the Kaon light quark sea, with a dbar -- ubar value of 0.2606. Using the Monte Carlo method of [2], the momentum distributions of the partons in the Kaon are calculated. These results for K$^{+}$ distributions are important for theoretical meson-cloud calculations of the strange sea asymmetry in the proton, which may resolve the NuTeV anomaly. This research has been supported in part by the Research in Undergraduate Institutions program of the National Science Foundation, Grant No. 0245101. \newline [1] Y-J. Zhang et al., Phys. Lett. B 523 (2001) 260 \newline [2] Y-J. Zhang et al., Phys Lett. B 528 (2002) 228 [Preview Abstract] |
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3A.00077: Momentum Corrections for Charged Particles Photoproduced on Christian Shultz, Richard Bonventre, Elliot Imler, Michael Vineyard Momentum corrections have been implemented and tested for charged particles photoproduced on Hydrogen and Helium targets in the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. This is part of a systematic study of meson photoproduction from the proton and Helium with the goal of investigating possible nuclear medium modifications of nucleon resonances and meson-nucleon interactions. The momenta of charged particles detected in CLAS are corrected for energy losses in the cryogenic targets and start counter by integrating a FORTRAN code written for this purpose into our C++ analysis code. The analysis will be described and the effects of the corrections on momentum and missing mass distributions will be presented. [Preview Abstract] |
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3A.00078: First observation of $^{109}$I alpha decay D. Simpson, C. Mazzocchi, R. Grzywacz, C.R. Bingham, A. Korgul, C.J. Gross, K.P. Rykaczewski, J.C. Batchelder, S.N. Liddick, J.H. Hamilton, J.K. Hwang, K. Li, S. Ilyushkin, J.A. Winger, W. Krolas, R.D. Page Charged particle spectroscopy can provide insight into the nuclear structure of exotic nuclei. Far away from the valley of stability nuclei become difficult to produce and observe. Short lifetimes and low count rates make experiments very challenging. One way to do these experiments is by implanting a nucleus into a silicon detector and observing its alpha or proton decay. At short lifetimes, the implantation induced signal distorts the energy measurement of the decay pulse. An algorithm was designed to correct this effect, making possible the observation of $^{109}$I alpha decay. The method and preliminary results will be presented. [Preview Abstract] |
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3A.00079: Statistical Analysis of Nucleon Resonances: Updating the Nuclear Data Ensemble D.J. Sissom, J.F. Shriner, Jr., G.E. Mitchell Statistical properties of both neutron and proton resonance data are thought to be described by the Gaussian Orthogonal Ensemble of Random Matrix Theory. The most convincing evidence is from the analysis by Haq \textit{et al.} of the Nuclear Data Ensemble (NDE),\footnote{Phys. Rev. Lett. \textbf{48}, 1086 (1982).} a collection of resonance levels from 32 different nuclides. Since the data that comprise the NDE are over 20 years old, it seems reasonable to examine current resonance data with the goal of providing an updated NDE. We have examined current resonance data not only for the nuclides in the original NDE but also for other even- even targets as well. Tests of data quality have included N(E) “staircase” plots and comparison of reduced width distributions with the Porter-Thomas distribution. New data exist for 16 of the 32 original nuclides, and data from five other nuclides also seem suitable for inclusion. A description of the new data set and results for several of the standard statistical measures, including the nearest-neighbor spacing distribution and the Dyson-Mehta $\Delta_3$ statistic, will be provided. [Preview Abstract] |
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3A.00080: One-Zone x-Ray Burst Model Adjustment Karl Smith, Matt Amthor, Alexander Heger, Emily Johnson, Hendrik Schatz Multi-zone x-ray burst models simulate thermonuclear explosions on the surface of accreting neutron stars. The underlying nuclear reaction sequence in the x-Ray burst is the rp-process. We explored the validity of one-zone approximations as tools to investigate nuclear physics by comparing to a full 1D multi-zone model. A one-zone model uses less computation time to run an x-ray burst than for a multi-zone model. The multi-zone model requires more time because it considers convection within the star. Our goal was to produce a one-zone model to quickly study changes in nuclear reaction rates, if interesting results were found to rerun the conditions with the multi-zone model. By changing the initial composition, temperature, and pressure in the one-zone model, we succeeded to match the x-Ray light curve and final produced ashes of the multi-zone model. [Preview Abstract] |
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3A.00081: Determination of Acceptance for the $\pi ^{- }p \to$ K Lambda Reaction Dolapo Soboyede, Michael Sadler ACU fairly recently became involved in an experiment proposed by the Institute for Theoretical and Experimental Physics (ITEP) and the Petersburg Nuclear Physics Institute (PNPI). In this experiment, our aim is to gain a better understanding of the second and third resonance regions in pion-nucleon scattering. In $\pi ^{-}p \to \pi ^{-}p$ scattering, the P$_{11}$ (1710) resonance is poorly seen, but in the $\pi ^{-}p \to {\rm K}\Lambda$ reaction the resonance is more clearly defined. In addition, previous experiments have been insensitive to narrow pion-nucleon resonances, but this experiment will be sensitive to such excited states of bound quarks. This research focuses on a GEANT4 simulation of the experiment and an analysis of the data using ROOT in order to determine the acceptance for the $\pi ^{-}p \to {\rm K}\Lambda$ reaction. Our experimental setup is designed to detect only charged particles, thus this simulation concentrates on charged decay modes. [Preview Abstract] |
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3A.00082: The Results of a Resistive Plate Chamber Study for the PHENIX Forward Muon Trigger Upgrade Nathan Sparks The aim of the PHENIX Forward Muon Trigger Upgrade is to allow the use of W boson physics, specifically the non-invariance of W decay under parity reversal, to elucidate a better understanding of the spin structure of the proton. A fast muon trigger system will be assembled by adding three Resistive Plate Chamber (RPC) stations to the existing PHENIX infrastructure at RHIC. There are a number of RPC prototypes being carefully studied to ensure that the upgrade succeeds. One such study is being conducted at the University of Illinois at Urbana-Champaign and involves the tracking of cosmic rays passing through an RPC test stand. The main objective of the study is to determine the cluster size, position resolution, efficiency, and rate capability of the RPCs. The analysis of the data collected during the study will be presented. [Preview Abstract] |
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3A.00083: Partial neutron induced gamma-ray cross section measurements of Pb at 8 and 12Mev for background subtraction of 0$\nu \beta \beta$ decay experiments B.N. Spaun, M.A. Atonacci, A.P. Tonchev, W. Tornow The Majorana collaboration is currently seeking to detect neutrinoless double beta decay (0$\nu \beta \beta )$ using $^{76}$Ge as both the source and detector. If 0$\nu \beta \beta $ decay were detected, it would indicate that neutrinos are there own antiparticles (Majorana particles), and it would provide an absolute mass scale for the three neutrino mass states. However, the predicted half life of such a decay is on the order of 10$^{27}$ years, making its detection above background extremely difficult. Although the $^{76}$Ge source and detectors are placed deep underground and shielded with lead, cosmic-ray muons still produce neutrons which interact with the lead shielding to produce gamma rays in the energy region of interest, 2040 keV. In an effort to determine the rate of neutron induced gamma production, we at TUNL, in collaboration with Los Alamos, have recently measured the partial cross section of several key lead transitions using both an 8 MeV and a 12 MeV neutron beam. We are especially interested in the partial cross sections of 2041 keV, 2614 keV, and 3062 keV lead transitions, which will directly interfere with the detection of 0$\nu \beta \beta $ decay events. We will present the results of these partial cross section measurements. Supported in part by DOE grant no. DE-FR02-97ER41003 and by NSF no. NSF-05-52723. [Preview Abstract] |
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3A.00084: Understanding Na22 Cosmic Abundances S. Stattel, J.A. Caggiano, L. Buchmann, J.M. D'Auria, D.A. Hutcheon, M. Trinczek, C. Vockenhuber, J. Pearson, C. Ruiz, K. Snover, J.J. Ressler, J. Jose, A. Sallaska, D. Storm, A. Garcia 22Na is an elusive cosmic gamma ray emitter that should be abundant as a product of novae, but this isotope is as of yet unobserved except in the central galactic bulge. The discrepancy could be resolved through a recent measurement of 23Mg structure, which discovered a level that may have significant implications on the rate for 22Na destruction via the 22Na(p,gamma)23Mg reaction. One of the main goals of this project is to perform a direct (p,gamma) measurement of the new resonance using a beam of protons that will be accelerated to impinge on a 22Na radioactive target. The target will be produced at TRIUMF-ISAC in Canada. We are currently in the beginning stages of setting up this experiment at CENPA. I will explain the motivations for the experiment, describe the set up, and present calculations that allow optimization of our beam-line design. [Preview Abstract] |
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3A.00085: Study of di-jets and the Sivers effect at STAR Justin Stevens, Steve Vigdor, Jan Balewski It has been known for a number of years that the preferential alignment of quark spins inside the proton can account for only a small fraction of the proton's total spin. The rest of the spin must arise from some combination of gluon spin alignment and parton orbital angular momentum. One possible manifestation of orbital angular momentum of the partons is the Sivers effect: transverse spin asymmetries that arise from a directional preference in the intrinsic transverse momentum of partons, correlated with the transverse spin direction of a polarized proton. One method of quantifying this effect is measuring high energy polarized proton collisions at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory using the STAR detector. The key to the analysis was di-jet events, where the Sivers effect would be manifested by a spin-dependent change in the azimuthal opening angle, zeta, between the two jets. Monte Carlo simulations were run in order to better understand the shape of the zeta distribution for these events. Also data from the 2006 run at STAR were analyzed using electromagnetic calorimeter information only, before charged-particle tracking information allowing full jet reconstruction was available. I will report an analysis looking in different subsets of the data where theory predicts non-zero Sivers effects should be, based on earlier experimental results for transverse spin asymmetries measured in semi-inclusive deep inelastic scattering from protons. [Preview Abstract] |
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3A.00086: Finite Size Effects on Dilepton Properties in Relativistic Heavy Ion Collisions Trent Strong, Hendrik van Hees, Ralf Rapp In order to understand better the basic properties of matter at the subnuclear level, relativistic heavy-ion collision experiments are utilized to explore the interactions of strongly interacting particles in hot and dense matter. A particularly valuable probe is dilepton radiation, since leptons do not strongly interact and therefore transmit direct information from the medium in which they were produced, in particular on the in-medium properties of vector mesons. Thus, electromagnetic probes could greatly enhance our understanding of the QGP and the relevant processes within, including information about phase transitions. Accordingly, the intent of this project has been to study recent data from the NA60 experiment and account for the observed dilepton spectrum by means of a two component model, which treats the spectra as being produced from separate thermal and non-thermal hadronic sources and aims to provide a consistent description of both invariant-mass and momentum spectra. [Preview Abstract] |
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3A.00087: Spectroscopic Factors of Mirror Nuclei Shi Chun Su Neutron spectroscopic factors have been extracted from all measured excited states of $^{36}$Cl, $^{27}$Mg, $^{35}$S and $^{31}$Si. These nuclei were chosen because of the availability of the (d,p) transfer reaction data and the astrophysical interest in the corresponding mirror nuclei ($^{36}$Ca, $^{27}$P, $^{35}$K and $^{31}$Cl). These latter four nuclei are important in the evolution theory of neutron stars. Since no SFs for these four nuclei are available experimentally, shell model is used to calculate them. To assess the uncertainties of the calculated SFs, we compare the experimental SF values to the calculated values from Oxbash. Three different interactions (USD, USDA and USDB) for sd shell nuclei are used. USDA and USDB are new interactions developed recently. The results from the three interactions agree to within 20{\%} when the experimental SFs are larger than 0.02. However, for SFs, as small as 0.003, good agreements can only be achieved with the new USDB interaction. The present work lowers substantially the validity limit of the shell model SFs calculations for the sd nuclei. It also quantifies the uncertainties of the calculated SF's. These theoretical uncertainties will be important to assess the outputs of the network calculations for evolution theory of neutron star. [Preview Abstract] |
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3A.00088: EPICS Slow Controls System in the Search for a Neutron Electric Dipole Moment Courtney Taylor The measurement of a nonzero electric dipole moment (EDM) of the neutron would significantly impact our understanding of the nature of the electro-weak and strong interactions. The goal of the current experiment is to improve the measurement sensitivity of the EDM by two orders of magnitude. The experiment is based on the magnetic-resonance technique of rotating a magnetic dipole moment in a magnetic field. The measurement of the neutron EDM comes from a measurement of the difference in the precession frequencies of neutrons when a strong electric field parallel to the magnetic field is reversed. This construction project is divided into a number of subsystems, five of which require automated control. The Experimental Physics and Industrial Control System (EPICS) is a slow-controls data acquisition (DAQ) system and is the system of choice for this experiment. It was selected for both its ease of use and ability to act as a total control system for large systems. As part of the initial research and development for the EDM project, we are setting up a prototype system that will eventually be copied and sent to the subsystem managers. This prototype consists of a VME crate housing a single board computer and DAQ modules. EPICS, running on a PC with CentOS Linux-x86, interfaces with the VME single board computer and provides a graphical user interface for the control system. The details on building this prototype DAQ system will be presented. Supported in part by the U.S. DoE. [Preview Abstract] |
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3A.00089: Limitations and Improvement of the Gamow Window Approximation for Thermonuclear Reaction Rates J. Tokiwa, R.L. Kozub, M.S. Smith, J.P. Scott, E.J. Lingerfelt, K. Chae The knowledge of thermonuclear reaction rates is vital to simulate numerous types of astrophysical events. Standard codes to calculate rates, such as the tools at nucastrodata.org, utilize a Gaussian approximation\footnotemark [1] to estimate the relative energy range (Gamow window) over which the calculation is performed numerically. This approximation fails by returning an energy range that extends to negative values for some reactions involving low Z particles at low temperatures, such as the d($d,n$)$^3$He and d($d,p$)t reactions, which are important for Big Bang Nucleosynthesis. A new code has been written to numerically determine the energy range for the calculation needed to obtain an accuracy of less than 1\% in the reaction rate, based on rate contributions from various energies in the Gamow window at a given temperature. This extends the rate calculation capabilities at nucastrodata.org to include Big Bang Nucleosynthesis. This research is supported by the U. S. Department of Energy under grants DE-AC05-00OR22725 (ORNL) and DE-FG02-96ER40955 (TTU). \footnotetext[1]{See, e.g., C. E. Rolfs and W. S. Rodney, ``Cauldrons in the Cosmos,'' The University of Chicago Press, Chicago (1988), p. 158.} [Preview Abstract] |
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3A.00090: $\mathbf{\vec{n}}$-d Analyzing Power at $\mathbf{E_{n} = 21.0}$ and 22.7 MeV Jeromy Tompkins, M.W. Ahmed, A.S. Crowell, J.H. Esterline, C.R. Howell, W. Tornow, B.J. Crowe III, R.S. Pedroni, G.J. Weisel, I. Slaus, H. Witala The $\vec{n}-d$ analyzing power $A_{y}(\theta)$ was measured for $E_{n} = 21.0$ MeV and $E_{n} = 22.5$ MeV. Polarized deuterons were accelerated using the TUNL FN-Tandem into a $^{2}$H gas cell to produce the incident polarized neutrons using the $^{2}$H($\vec{d},\vec{n})^{3}$He source reaction. We used a deuterated scintillator as the center detector in our $A_{y}(\theta)$ measurements and a $^{4}$He gas cell to determine the beam polarization. $A_{y}(\theta)$ values were taken at lab angles $39^{\circ}$, $60^{\circ}$, $81^{\circ}$, $94^{\circ}$, $107^{\circ}$, and $128^{\circ}$. This data addresses the long standing discrepancy between rigorous three-nucleon calculations and experimental data (3NAPP) in the unexplored neutron energy range from 19.0 to 30.0 MeV. Our results confirm the 3NAPP. They also show a sensible trend in the maxima and minima between $E_{n} = 19.0$ and 30.0 MeV. This suggests that the theoretical treatment of the three-nucleon systems needs revision. \\ \\ Funded by the NSF (NSF-PHY-05-52723) and the DOE, Office of Nuclear Physics (DE-FG02-97ER41033). [Preview Abstract] |
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3A.00091: Two-Body Scattering Observables in a Truncated Harmonic Oscillator Basis J. Torkkola, B. Barrett, I. Stetcu, U. van Kolck The no-core shell model (NCSM) is a powerful many-body method which provides the solution to the Schr\"odinger equation for $A$ interacting nucleons in a restricted space [1]. The conventional approach uses high precision nucleon-nucleaon (NN) potentials (and three-body forces) and involves a unitary transformation that takes into account the truncation of the (infinite) Hilbert space to a model space which allows for an exact large-scale diagonalization. However, in the process, one has to make a cluster approximation, which is under control for some observables (short-range observables), but less so for others (long-range observables) [2]. Based on a effective field theory (EFT) that integrates out the pions as degrees of freedom (pionless theory), we present a new approach to the derivation of effective interactions suitable for many-body calculations to be used within a NCSM framework. In this contribution, we concentrate on the description of two-body scattering observables in a restricted harmonic oscillator (HO) basis, and the inherent Gibbs oscillation problem that arises from the truncation of the Hilbert space using HO wave functions. In particular, we investigate the connection between the results obtained in leading order in the restricted HO basis and the corresponding continuum results. [1] P. Navratil, J. P. Vary, and B. R. Barrett, Phys. Rev. Lett. 84, 5728 (2000). [2] I. Stetcu, B. R. Barrett, P. Navratil, and J. P. Vary, Phys. Rev. C 71, 044325 (2005); ibid. 73, 037307 (2006). [Preview Abstract] |
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3A.00092: Measurement of the Neutral Pion $A_{LL}$ with the PHENIX Muon Aaron Veicht The PHENIX experiment at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory commissioned a new forward calorimeter during the 2006 polarized proton run. The Muon Piston Calorimeter, MPC, is a $PbWO_4$ based electromagnetic calorimeter that will cover $3.1<\eta<3.65$ in pseudo rapidity and $2\pi$ in azimuthal angle. The MPC will be able to reconstruct neutral pions with momenta up to $p \sim 10 GeV$, allowing a measurement of the double helicity asymmetry $A_{LL}$ in a kinematic region previously inaccessible in the PHENIX experiment. In this poster I will present the commissioning, operation, and calibration of the MPC, as well as the latest status from the analysis of the neutral pion $A_{LL}$ from the $\sqrt{s} = 62 GeV$ run at RHIC. [Preview Abstract] |
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3A.00093: Muon Piston Calorimeters for the PHENIX Forward Upgrade at RHIC Cole Watts New forward electromagnetic calorimeters for the PHENIX experiment at Brookhaven National Laboratory have been integrated into the PHENIX muon spectrometer magnet yokes. The two~Muon Piston Calorimeters (MPCs) each consist of an array~of PbWO$_{4}$ crystals, closely installed~around the beam pipe.~The South MPC was installed during the RHIC shutdown in 2005, while the North MPC, still in construction, is scheduled to be installed during the RHIC shutdown in 2006. The detectors~have an angular acceptance of 3.1 $<$ eta $<$ 3.65 and 0 $<$ phi $<$ 2pi in azimuth. The two~MPCs make it possible to measure cross sections and spin asymmetries~for neutral pions in d-Au and polarized proton-proton collisions, respectively.~We discuss the detector design, as well as the assembly and integration of the MPC in PHENIX, including the techniques used to prepare the PbWO$_{4}$ crystals. [Preview Abstract] |
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3A.00094: Search for Cosmic Neutrinos Using UHE Upward-Going Muons in SK-II Katie West Astrophysical models predict a diffuse flux of cosmic neutrinos which should be an observable excess to the diffuse flux of atmospheric neutrinos at higher energies. Such high energy neutrinos are postulated to come from cosmic accelerators such as Active Galactic Nuclei (AGN's), and Gamma Ray Bursts (GRB's). This study searches for HE neutrinos (in the 1 TeV range) among Super-Kamiokande II's highest energy sample by looking for ultra-high energy upward-going muons induced by HE neutrinos interacting in the rock beneath the detector. A total of three UHE-upmu candidates were found in 860.37 days of live-time. We are now in the process of determining the efficiencies of the cuts that were made. The search will be used to place a 90{\%} classical confidence level limit on an assumed E$^{-2}$ spectrum for cosmic neutrino flux. [Preview Abstract] |
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3A.00095: Setting limits on a new parameter outside of Standard Model muon decay. Kristen Williams This work is a response to predictions concerning a new tensor interaction which is outside of the Michel local interactions of Standard Model muon decay. This interaction is assumed to be parameterized by the addition of a new variable, $\kappa $, to the differential decay probability spectrum. The \textit{TWIST} experiment is measuring the Michel parameters $\rho $, $P_{\mu }\xi $, and $\delta $ in muon decay to search for deviations from the Standard Model. Our analysis was of the approximate contribution that $\kappa $ would make to the \textit{TWIST} measurements and the sensitivity of this contribution to the fitted momentum range. Efforts were made to set a limit on $\kappa $ in accordance with both past \textit{TWIST} fit ranges and assumed future ones. [Preview Abstract] |
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3A.00096: Proton Recoil Detectors and Fission Ionization Chambers for Neutron Dosimetry Brent Wilson, Peggy McMahan, Brad Barquest, Mike Johnson This research involved the creation and development of detectors for the measurement of neutron flux. These detectors will be utilized to obtain dose information for fast neutron irradiations of electronic components, materials, and biological samples in the new neutron beamline at the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory. As a first step, we have developed two well-established neutron detectors –- the proton recoil detector and the fission ionization chamber –- for the energy range of the neutrons at our facility, 5 to 30 MeV. Using activation foil measurements (to obtain absolute neutron flux) and time-of-flight measurements with a Stilbene detector (to obtain the neutron energy spectra), we can calculate the efficiency of our detectors for both monoenergetic and white spectrum neutrons in this energy range. [Preview Abstract] |
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3A.00097: Data Acquisition in Research and Development of Resistive Plate Chambers for the Trigger Upgrade for the PHENIX experiment at RHIC John Wood To study the contributions of different flavors of quarks to the total spin of the proton, the PHENIX experiment at RHIC is installing a first-level trigger system employing Resistive Plate Chambers (RPC's). The trigger will allow data to be taken from the decay of bosons produced in the parity-violating interactions of quarks during polarized p-p collisions with far less background by triggering on detection of high-p${_t}$ muons produced during the decay. Prototypes of RPC's are being built with different materials and tested at the University of Illinois to determine characteristics such as position resolution, timing resolution, and rate capability. The data acquisition system and visualization softwar for the test stand is presented in this poster. The system uses a number of CAMAC modules including a Jorway 73A crate controller. [Preview Abstract] |
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3A.00098: Resistive Plate Chamber Test Stand and Read Out System for the PHENIX RPC Forward Upgrade Ryan Wright The PHENIX experiment, using the Relativistic Heavy Ion Collider at BNL, uses polarized proton-proton collisions to study the origin of the proton spin. In order to facilitate this, the forward muon arms are being upgraded in order to provide a first level trigger for high p$_{T}$ muons resulting from W-boson interactions. The new trigger will be based on fast Resistive Plate Chambers to provide a fast trigger to reject low momentum muons. A test stand at the University of Illinois Urbana-Champaign has been set up to study the behavior of a small RPC. The setup used for the research contains drift chambers, scintillators, and a multitude of electronics for data acquisition. This allows for the tracking of cosmic rays through the RPC to study details of the behavior of the RPC. The test setup and goals of the research will be presented, with special attention given to the read out system and the pre-amps for the data acquisition. [Preview Abstract] |
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3A.00099: Optics Simulations for the optimization of the CLAIRE Ion Beam Extraction and Transport System Nan Xu, Damon Todd, Daniela Leitner CLAIRE (Center for Low Energy Astrophysics and Interdisciplinary REsearch) is a proposed nuclear astrophysics facility under design at the Lawrence Berkeley National Laboratory. The facility will measure cross sections relevant to stellar burning, namely $^{3}$He($^{4}$He,$\gamma )^{7}$Be, a reaction which is one of the leading sources of uncertainty when correlating solar neutrino data with theoretical solar models. A beam line concept has been developed to extract and transport a tightly focused ($<$5mm), high current (100mA), low energy (50keV$\sim $300keV) $^{3}$He$^{+}$ ion beam to a high density$^{ }$gas jet target. The beam is first extracted from a plasma ion source, and is then focused by two solenoid lenses mounted on a 300kV high voltage (HV) platform. The envelope of the accelerated beam leaving the HV platform is kept as small as possible by another lens before going through a 60\r{ } analyzing magnet. The last focusing solenoid lens produces the desired beam size on the target. An extensive simulation program was employed to optimize the extraction and the transport of the beam over the desired energy range. The detailed analysis of this simulation will be shown and discussed. [Preview Abstract] |
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