Session GB: Conference Experience for Undergraduates Poster Session (1:30-3:00PM)

Studies of the Magnetic Field Interference in the UCN$\tau$ Experiment

The mean lifetime of free neutrons undergoing beta decay is an important parameter in the Standard Model of particle physics and nuclear-astrophysics. The UCN$\tau$ experiment is designed to measure the neutron lifetime to a better precision than the existing world average value, hoping to resolve the puzzle of large discrepancies between measurements using different methods. In the UCN$\tau$ apparatus, ultracold neutrons (UCNs) are trapped by gravity from the top and reflected by the magnetic force from an array of permanent magnets. However, this magneto-gravitational trap is located in close proximity of the high magnetic field (7 T) created in the adjacent UCNA experiment. Because the magnetic field within the neutron trap is integral to storing the neutrons, any interference potentially creates a serious systematic effect. In particular, cancellations of the fields could lead to depolarization that shortens the neutron storage time. Measurements of the field from UCNA were used to construct magnetic field simulations that when combined with similar simulations of the UCN$\tau$ field allow the effects from UCNA on UCN$\tau$ to be studied. We report the results of these simulations and the methods used to perform them, and discuss means of mitigating the magnetic interference.   

An Ortho/Para Deuterium Converter for Ultra-Cold Neutron Production at Los Alamos National Laboratory

The production of Ultra-Cold Neutrons (UCN) is essential for a number of experiments whose goal is to make precise measurements of neutron properties. With order-of-magnitude improvements in precision provided through the use of UCN, scientists plan to push towards physics beyond the Standard Model. At Los Alamos National Laboratory (LANL) a solid deuterium target is used for UCN production. As a result of previous studies, it is known that the storage time of UCN is dependent on the spin state of the deuterium target. The spin $=$ 1 state of deuterium (para-D$_{2})$, in which approximately one-third of the D$_{2}$ molecules can be found, results in a shorter UCN residence time. Therefore, to lengthen the storage time, a conversion to the ground state (ortho-D$_{2})$ is required. Because, in a solid sample of D$_{2}$ it would take months for the sample to spontaneously relax to the required percentage of 99.8{\%} ortho-D$_{2}$, an Ortho/Para converter is used to accelerate the conversion. This project focuses on the design of a new, improved Ortho/Para Converter. The production of UCN at LANL and the work done to design the new Ortho/Para Converter for the LANL UCN system will be discussed.   

The Adiabatic Fast Passage magnet for Ultracold Neutron spin manipulation

The Ultracold Neutron source at the Los Alamos Neutron Science Center is used to investigate the weak interaction of the Standard Model through the decay of the free neutron, such as a precise measurement of the correlations between the decaying neutron's polarization and the emitted electron or neutrino momenta (the A and B correlation coefficients). These angular correlation measurements require precise control of the neutron polarization. The neutrons are polarized by a 7-Tesla magnetic field, and their spins are flipped by a radio-frequency birdcage resonator using the adiabatic fast passage technique in a 1-Tesla field. Precise knowledge of their polarization and spin-flip efficiency requires the achievement of greater than roughly 99\% polarization and 99.9\% spin-flipper efficiency. This target performance requires precise characterization and control of the static magnetic field profile in the spinflipper, and the resonator must produce large, uniform radio-frequency fields at 29.2 MHz. Studies of the static field profile in our spin-flipper and measurements of the performance of a modified resonator utilizing silver-coated components will be presented along with its impact of our measurements and the system's performance optimization.   

Design of a magnetic field mapping rover system for a neutron lifetime experiment

The beta decay lifetime of the free neutron is an important input to the Standard Model of particle physics, but values measured using different methods have exhibited substantial disagreement. The UCN$\tau$ experiment in development at Los Alamos National Laboratory (LANL) plans to explore better methods of measuring the neutron lifetime using ultracold neutrons (UCNs). In this experiment, UCNs are confined in a magneto-gravitational trap formed by a curved, asymmetric Halbach array placed inside a vacuum vessel and surrounded by holding field coils. If any defects present in the Halbach array are sufficient to reduce the local field near the surface below that needed to repel the desired energy level UCNs, loss by material interaction can occur at a rate similar to the loss by beta decay. A map of the magnetic field near the surface of the array is necessary to identify any such defects, but the array's curved geometry and placement in a vacuum vessel make conventional field mapping methods difficult. A system consisting of computer vision-based tracking and a rover holding a Hall probe has been designed to map the field near the surface of the array, and construction of an initial prototype has begun at LANL. A description of the design and prototype will be presented.   

The Art of Neutron Spin Flipping

Low energy precision measurements complement high energy collider results in the search for physics beyond the Standard Model. Neutron spin rotation is a sensitive technique to search for possible exotic velocity and spin-dependent interactions involving the neutron from the exchange of light ($\sim$ meV) spin 1 bosons [1-3]. We plan to conduct such searches using beams of cold neutrons at the Los Alamos Neutron Science Center (LANSCE) and the National Institute of Standards and Technology (NIST). To change the spin state of the neutrons in the apparatus we have developed an Adiabatic Fast Passage (AFP) neutron spin flipper. I will present the mechanical design, static and RF magnetic field modeling and measurements, and spin flip efficiency optimization of the constructed device. I would like to acknowledge the NSF REU program (NSF-REU grant PHY-1156540) and the Indiana University nuclear physics group (NSF grant PHY-1306942) for this opportunity.\\[4pt] [1] F. M. Piegsa and G. Pignol, Phys. Rev. Lett. 108, 181801 (2012)\\[0pt] [2] E. G. Adelberger and T. A. Wagner, Phys. Rev. D 88,031101(R) (2013)\\[0pt] [3] H. Yan, and W. M. Snow, Phys. Rev. Lett. 110, 082003 (2013)\\[0pt]   

Radiative Capture Cross Sections of $^{139}$La(n,$\gamma$) for Thermal Neutrons

A set of partial-production neutron-capture $\gamma$-ray cross sections corresponding to the $^{139}$La$(n,\gamma)$ reaction were measured at the Budapest Research Reactor using a supermirror-guided near-thermal neutron beam. Absolute values for these quantities were obtained through an internal-standardization procedure where the observed $\gamma$-ray intensities were normalized to well-known comparator $^{35}$Cl($n,\gamma$) transitions using a LaCl$_{3} \cdot 7{\rm H}_{2}$O standard. These measurements have been used, together with statistical-model predictions calculated using the Monte Carlo program DICEBOX to simulate the thermal-capture $\gamma$-ray cascade, to evaluate the decay scheme of the compound nucleus $^{140}$La. An independent measurement of the total radiative thermal neutron-capture cross section, $\sigma_{0}$, has also been determined; our preliminary result $\sigma_{0} = 8.51(43)$ b, is consistent with earlier literature. The total mean capture-state width is currently being investigated and may provide further insight into the validity of the Brink hypothesis in $\gamma$ decay.   

Investigations of p-type point contact detectors for the MAJORANA Experiment

The importance of studying neutrinoless double-beta decays and techniques used to do so are described. The use of germanium detectors to search for such decays is of particular interest because of their high intrinsic energy resolution. Germanium detectors also represent a mature technology, as they have been used extensively in many applications for several decades. The MAJORANA DEMONSTRATOR project uses novel p-type, point-contact (PPC) germanium detectors, enriched to 87\% Ge-76, to search for those rare decays. This poster will present the results of a characterization study on the temporal stability of PPC germanium detectors. Any instability could potentially influence the sensitivity to the search for neutrinoless double-beta decays.   

Front-End Electronics Characterization, Production, and QA for the Majorana Demonstrator

The Majorana Demonstrator will search for the neutrinoless double beta decay $\beta\beta(0\nu)$ of the isotope $^{76}$Ge. In anticipation of the future tonne-scale experiments, its goal is to demonstrate a path forward to a background rate of one cnt/(ROI-t-y) in a 4 keV region around the Q-value of the $^{76}$Ge $\beta\beta(0\nu)$. Such a background requirement significantly constrains the design of the front end electronics. Low background and low noise qualifications are a necessity. This poster first presents the characterization and noise performance in single and multi detector systems of the front end electronics developed for {\sc Majorana} . The poster next reviews the full production process and finally describes the Quality Assurance tests developed for the electronics before installation in the experiment.   

The trigger card system for the MAJORANA DEMONSTRATOR

The aim of the MAJORANA DEMONSTRATOR is to demonstrate the feasibility of providing low enough background levels to search for neutrinoless double-beta decay (0$\nu \beta \beta )$ in an array of germanium detectors enriched to 87{\%} in $^{\mathrm{76}}$Ge. Currently, it is unknown if this decay process occurs; however, observation of such a decay process would show that lepton number is violated, confirm that neutrinos are Majorana particles, and yield information on the absolute mass scale of the neutrino. With current experimental results indicating a half-life greater than 2 x 10$^{\mathrm{25}}$ years for this decay, the minimization of background events is of critical importance. Utilizing time correlation, coincidence testing is able to reject multi-detector events that may otherwise be mistaken for 0$\nu \beta \beta $ when viewed independently. Here, we present both the hardware and software of the trigger card system, which provides a common clock to all digitizers and the muon veto system, thereby enabling the rejection of background events through coincidence testing. Current experimental results demonstrate the accuracy of the distributed clock to be within two clock pulses (20 ns) across all system components. A test system is used to validate the data acquisition system.   

Ge Detector Data Classification with Neural Networks

The \textsc{Majorana Demonstrator} experiment is searching for neutrinoless double beta-decay using p-type point contact \textit{PPC} germanium detectors at the Sanford Underground Research Facility, in South Dakota. Pulse shape discrimination can be used in PPC detectors to distinguish signal-like events from backgrounds. This research program explored the possibility of building a self-organizing map that takes data collected from germanium detectors and classifies the events as either signal or background. Self organizing maps are a type of neural network that are self-learning and less susceptible to being biased from imperfect training data. We acknowledge support from the Office of Nuclear Physics in the DOE Office of Science, the Particle and Nuclear Astrophysics Program of the National Science Foundation and the Russian Foundation for Basic Research.   

Stopping Muons Study for Ultra-Low Background Experiments

Stopping negative muons can be captured by nucleus in various materials in which neutrons and gamma rays can be produced. These energetic secondary particles can be background events for ultra-low background experiments in searching for dark matter and neutrinoless double-beta decay. The stopping negative muons captures rates in different materials have been mostly evaluated theoretically. The secondary particles in particular the energy of neutrons is not well understood for heavy elements. Experimental study of the capture rates and secondary particles is of interest of nuclear physics and rare event physics. Two plastic scintillation panels were used to create a muon detection system allowing study of stopping muons. These panels are each made of EJ200 scintillator measuring approximately 100x50x2.54cm and attached on one side to EJ280 plastic strip measuring 2.54x2.54x50cm. A 1'' Hamamatsu R1924A PMT is affixed to the end of each strip to collect light. The setup measures the lifetime of muons at earth's surface by detecting the time difference between stopped muons and muon decay. Data is collected for 21 hours and a mean muon lifetime of 2.02 $\pm$ .06 microseconds is obtained. The setup will be used at Homestake to measure captures rates and secondary neutron energy spectrum.   

Automation of the Characterization of High Purity Germanium Detectors

Neutrinoless double beta decay is a rare hypothesized process that may yield valuable insight into the fundamental properties of the neutrino. Currently there are several experiments trying to observe this process, including the Majorana DEMONSTRAOR experiment, which uses high purity germanium (HPGe) detectors to generate and search for these events. Because the event happens internally, it is essential to have the lowest background possible. This is done through passive detector shielding, as well as event discrimination techniques that distinguish between multi-site events characteristic of gamma-radiation, and single-site events characteristic of neutrinoless double beta decay. Before fielding such an experiment, the radiation response of the detectors must be characterized. A robotic arm is being tested for future calibration of HPGe detectors. The arm will hold a source at locations relative to the crystal while data is acquired. Several radioactive sources of varying energy levels will be used to determine the characteristics of the crystal. In this poster, I will present our work with the robot, as well as the characterization of data we took with an underground HPGe detector at the WIPP facility in Carlsbad, NM (2013).   

Setting Limits on Double $\beta$ Decay of $^{136}$Xe to the Excited State of $^{136}$Ba using EXO-200

When a single $\beta$ decay is energetically forbidden, it is possible for certain even-even nuclei to undergo the very rare process of two neutrino double $\beta$ decay ($2\nu\beta\beta$). Further, the $2\nu\beta\beta$ decay to the excited state of a daughter nucleus has been directly observed for $^{150}$Nd and $^{100}$Mo with half lives on the order of 10$^{20}$ years, several orders of magnitude longer than the age of the universe. A better understanding of this type of decay could put constraints on current models for nuclear matrix elements. Using data from EXO-200, a 110-kg liquid xenon time projection chamber designed to search for the neutrinoless double $\beta$ decay ($0\nu\beta\beta$) of $^{136}$Xe, we search for the $2\nu\beta\beta$ decay of $^{136}$Xe to the first 0$^+$ excited state of $^{136}$Ba, a process expected to have a half life on the order of 10$^{25}$ years.   

Calculating Neutrino Oscillations with Sterile Neutrinos

In particle physics, it is currently known that three types of neutrinos exist that interact via the weak force. Referred to as ``flavors,'' they are distinguishable and named for the lepton they produce through charged current interactions: electron, muon, and tau. In a process called neutrino oscillation, one flavor of neutrino can change into another flavor as it propagates through space. At the moment, mild discrepancies between expected and measured neutrino oscillations suggest that more types of neutrinos that do not interact via the weak force exist: sterile neutrinos. The goal of this project was to calculate non-sterile flavor oscillation probabilities when 1, 2 or 3 sterile neutrinos were assumed to exist. An application has been written in Mathematica that calculates these probabilities with the neutrino masses, linear relationships between mass and flavor states, values of CP symmetry violating constants, and constant densities of media in which the neutrinos propagate set as parameters. The application was published online for researchers to use as a tool when considering the existence of sterile neutrinos. In the immediate future, the insights this application gives into neutrino oscillations will be studied and reported.   

Producing Mono-energetic Neutrons for Research

Free neutrons are seldom produced in nature and are unstable, decaying back to protons with a mean life of 881s. The only natural sources are spontaneous fission of actinides and cosmic ray interactions, both of which are rare processes. The detection of neutrons indicates unusual nuclear activity, allowing neutron detection the roll of the ``smoking gun'' for seeking potential nuclear terrorism. Recently, there has been a push for the development of new neutron detectors, ideally sufficiently inexpensive that a detector can be carried by all first responders such as police and fire fighters. One promising new material is the inorganic scintillator CLYC, a crystal of chlorine, lithium, yttrium and cesium. CLYC has a high energy resolution not only for gamma rays, but also for fast neutrons. At the University of Massachusetts, Lowell, CLYC is being developed in collaboration with local industrial companies. To evaluate its response to neutrons, in to 500keV to 4MeV energy range, the CN Van de Graaff generator is used to produce neutrons, via the 7Li(p,n)7Be reaction. However, the important energy regime of 4-10MeV is currently inaccessible. This current project is to build a gas-cell target to enable the D(d,n)3He reaction and produce neutrons of energy up to 9MeV, an approach that has been used successfully at the University of Kentucky. The project involves some mechanical engineering management, then chamber construction, vacuum testing, developing thin window technology, and finally commissioning of the gas cell using accelerated beams. The commissioning will be physics rich in quantifying the flux and energy resolution of the neutron beam produced.   

Magnetic Field and Particle Tracking Simulations for Project 8

Project 8 is a new experiment being developed to measure the neutrino mass. The neutrino mass is measured by using the energy of electrons that are emitted from the beta-decay of tritium. Each decay of tritium releases an electron and an antineutrino. Since the beta-decay energy distribution depends on whether the neutrino is massive or not, a measurement of this distribution is equivalent to a neutrino mass measurement. Project 8 will detect the electron energy by looking at the cyclotron frequency of the electron due to the fact that the electron is moving within a magnetic field. Currently, Project 8 is using a NMR magnet and a ${}^{83}$Rb source to see if the proposed experiment would be plausible. ${}^{83}$Rb decays to ${}^{83{\mathrm{m}}}$Kr, and then to ${}^{83}$Kr. Electrons are emitted in the decay of ${}^{83{\mathrm{m}}}$Kr to ${}^{83}$Kr with the energy of 18 keV and 32 keV. I run magnetic field simulations to characterize the field that the electrons move in and simulations that track electron movement inside the magnetic field. I also work with the prototype and assist with data runs and hardware. I will be presenting field and electron tracking simulations and analysis from data runs.   

Wavelength Shifters and Interactions of EDTA with Acrylic {\&} LAB

The SNO$+$ experiment, an upgrade to the Sudbury Neutrino Observatory, will use linear alkyl-benzene (LAB) liquid scintillator to probe new physics, including 0$\nu \beta \beta $ decay. Event detection efficiency is heavily affected by radioactive backgrounds, two sources being Rn-222 and Po-210 daughters, some of which has become embedded in the SNO$+$ acrylic vessel after years underground. The leading candidate for polonium leaching is Ethylenediaminetetraacetic acid (EDTA). Before deployment on-site, EDTA's effects on the mechanical integrity of acrylic must be determined. It also must not be soluble in LAB or must be removed before scintillator fill of the vessel, as its presence would result in reduced light yield due to scattering. It was found that EDTA had negligible effects on the Young's Modulus of acrylic. EDTA is also slightly soluble in LAB, but can be completely removed by rinsing with water. Additionally, the study of the light yield and alpha/beta timing profiles of two wavelength shifters -- bisMSB and perylene -- is critical to determining which should be added to the 0$\nu \beta \beta $ isotope (tellurium) LAB cocktail. Small-scale results hint that perylene might be better, but this is being confirmed with larger-scale tests.   

Spectral Study of a Broad Energy HPGe Detector for First Measurement of Coherent Neutrino Scattering

Intense neutrino flux at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) in the energy domain below E$_\nu$ = 50MeV makes SNS a suitable location for measurement of Coherent Neutrino Scattering. Coherent scattering is assumed to occupy vital roles in supernovae (SN) events and measurement offers promising insight into SN mechanics and advancements in SN-$\nu$ detection. Furthermore, this interaction is well-calculable and therefore, a strong test of the Standard Model. P-Type Point Contact High-purity germanium detectors are excellent candidates for this measurement due to their sensitivity to low-energy nuclear recoils. One such, a Canberra Broad Energy HPGe detector, was tested for quality degradation from exposure to fast neutrons in the SNS target building, to assess usefulness in a future coherent scattering experiment. Analysis of the lead-shielded spectra was handled using tools developed for the \textsc{Majorana Demonstrator} neutrinoless double-beta decay experiment. Broad spectrum energy resolution and \textsuperscript{68}Ge decay rates were calculated. This poster will present findings that will help determine this detector's eligibility and exposure limitations for measurement in a future coherent neutrino scattering experiment at the SNS.   

SuperORRUBA in the JENSA Gas Target

The Jet Experiments in Nuclear Structure and Astrophysics (JENSA) gas jet target is a state-of-the-art device for performing beam experiments with gas targets.\footnote{K. A. Chipps et al., NIM A, in press (2014).} Experiments with pure hydrogen and helium targets are especially useful for astrophysics studies. JENSA can accommodate a large silicon detector array, such as SuperORRUBA (Oak Ridge Rutgers University Barrel Array) so that a large angular range for detecting charged particles can be covered in any experiment. A structure to hold such an array is being designed using modeling and CAD software. The structure can be rotated and translated relative to the beam axis. A number of designs are being considered, the status of which will be presented. This work was supported by the U.S. Department of Energy and CNPq - Brazil (National Council for Scientific and Technological Development).   

Measurement of the $^{19}$F($\alpha$,n) Cross Section for Nuclear Safeguards Science

A precise measurement of the $^{19}$F($\alpha$,n) cross section will improve Non Destructive Assays (NDA) of UF$_{6}$ and other actinide-fluoride samples via neutron detection techniques. The cross section will be determined with two complementary approaches. We have already bombarded a LaF$_{3}$ target with a pulsed $^4$He beam from the Notre Dame FN tandem accelerator; next, we will send a fluorine beam from the ORNL tandem through a pure helium gas target. The neutron spectra from both of these reactions will be measured using the Versatile Array of Neutron Detectors at Low Energy (VANDLE), and coincident $\gamma$ rays with a HPGe detector. We report here on data taken with VANDLE and a HPGe detector on a LaF$_{3}$ target. This poster outlines the motivation for this experiment, explains the stages of this experiment, and presents both of our experimental setups and preliminary data.   

Upgrading the Vandle Analysis code for Transfer Reactions

The Versatile Array of Neutron Detectors at Low Energy (VANDLE) is a detection system composed of over 200 plastic scintillating bars of various sizes. The detector setup is highly modular and therefore can be optimized to meet the experimental requirements for beta-delayed neutron and transfer reaction experiments which are important for nuclear structure and astrophysics. When mounted in an array around the target VANDLE has good angular resolution with a high intrinsic efficiency. Recent $(\alpha,n)$ and $(d,n)$ experiments require enhancements to the custom analysis code in order to determine transferred energy in the center of mass frame. We present results of the enhanced analysis code and some preliminary transferred-energy spectra for $^{19}F(\alpha,n)\:^{22}Na$.   

Development of the new trigger for VANDLE neutron detector

Beta-delayed neutron emission ($\beta $n) is the dominant decay channel for the majority of very neutron-rich nuclei. In order to study these decays a new detector system called the Versatile Array of Neutron Detectors at Low Energy (VANDLE) was constructed. A critical part of this neutron time of flight detector is a trigger unit. This trigger is sensitive to electron from beta decay down to very low energies, insensitive to gamma rays and have a good timing performance, better than 1 ns. In order to satisfy these condition, we have developed a new system, which utilizes plastic scintillator but uses recently developed light readout technique, based on the so called Silicon Photomultiplier, manufactured by Sensl. New system has been developed and performance tested using digital data acquisition system at the University of Tennessee and will be utilized in future experiments involving VANDLE.   

Characterization of Silicon Photomultiplier based detectors with digital electronics

Due to their compact design and good timing performance Silicon Photomultipliers (SiPMT) were chosen to be used to readout the light from the plastic scintillator detector used as a trigger for the Versatile Array of Neutron Detectors at Low Energy (VANDLE) [1,2]. Prior to development of the new system, we have performed proof of principle studies, to demonstrate that the SiPMT, provided by Sensl [3] is a viable replacement for the conventional photomultiplier. We have build a prototype detector, develop electronics readout chain and characterized its performance using the Digital Data Acquisition system at the University of Tennessee. This experience led to construction of segmented trigger detector which will be used in future VANDLE experiments. *This research was sponsored in part by the National Nuclear Security Administration under the Stewardship Science Academic Alliances program through DOE Cooperative Agreement No. DE-FG52-08NA28552 and the DOE Office of Nuclear Physics. \\[4pt] [1] C. Matei et al., Proceedings of Science, NIC X, 138 (2008).\\[0pt] [2] S. Paulauskas et al., NIM A 737, 22 (2014).\\[0pt] [3] http://sensl.com/products/silicon-photomultipliers/   

Investigation of the Sensitivity of WATCHMAN to Measure the Neutrino Mass Hierarchy

WATCHMAN is a gadolinium-doped water-Cherenkov reactor-monitoring antineutrino detector currently under development for nuclear nonproliferation purposes. Experimental sites under consideration lie 13 km and 20-25 km away, respectively, from the nearest nuclear reactor. We simulate the response of a WATCHMAN-type detector receiving a 100 GW$\cdot$kt$\cdot$yr exposure from a reactor 13 km away. We transform the detected electron-antineutrino disappearance oscillation spectrum from $L/E$ space into the $|{\Delta}m^2|$ frequency domain. There, we perform a shape analysis on the Fourier peak geometry in the hierarchy-dependent region around $|{\Delta}\mathrm{m}^2_{31}|$ to attempt a mass hierarchy reconstruction. We find that the WATCHMAN detector at 13 km lies in a previously undiscovered region of sensitivity to the ordering of the neutrino masses, and that for some regions of the oscillation parameter space, a mass hierarchy determination is achievable.   

Explosive Material Identification via Neutron-Induced Gamma Rays

With the increase in the usage of improvised explosive devices, both vehicle-borne and buried, it has become increasingly important to quickly identify potentially explosive materials before they can be detonated. In a field test performed in January of 2014, 14 MeV neutrons generated in a deuterium-tritium reaction induced gamma emissions in explosive material targets. The resulting gamma rays were counted in LaBr3 detectors in both a time-binned associated particle imaging (API) mode and a repetitively pulsed mode. The details of the resulting data sets were analyzed, and gamma lines for carbon, oxygen, and nitrogen were identified in the spectra produced by both modes. Post-test noise reduction techniques included empty hole background subtraction, Compton background subtraction, peak area integration, and time-of-flight gating. The induced C, O, and N gamma line intensities and ratios were compared to the elemental weight ratios expected for each type of material. The composition results are indicative of the known elemental weights in the target materials. The statistics are limited because of the short, 20 second data collection periods, and would improve greatly with longer exposure times in the future.   

Beam optics studies for a uranium ion micro-beam

The proposed XMAT (eXtreme MATerials) facility at the Argonne Advanced Photon Source (APS) promises to advance our understanding of and aid in the development of advanced materials for fusion and fission reactor fuels and structural elements. An ion-beam accelerator for this facility is being designed by the nuclear physics accelerator group in the Argonne Physics Division. The ion energy of $\sim$ 1 MeV/u was chosen to create damage at a depth of 10 microns, far enough below the surface to affect the bulk material. By co-locating this accelerator at the APS, the XMAT facility will have the unique capability of in-situ 3D X-ray imaging of the material as the damage evolves in time. This sub-project is to design the focusing optics with the high accuracy needed to simulate a heavy ion micro-beam to deliver at least 10$^{7}$ ions/s into a 10 micron diameter spot. The plan is to use 2 superconducting solenoids, a first stage magnification of 0.2 and the second 0.5 to achieve an overall flux density increase of 100 times that at the linac output while maintaining a final working distance of at least 50 cm between the superconducting solenoid and the sample. High accuracy transfer maps using COSY Infinity and a custom-written ion tracking program have been shown to agree at the sub-micron level.   

A Fast Ionization Chamber for GODDESS

Transfer reactions are among the main methods used in nuclear physics to probe the structure of nuclei. Such information is needed to constrain nuclear models and to understand various nucleosynthesis processes. In many cases, the nuclear level densities are too high to be resolved in transfer reactions via charged particle detection alone. This problem and issues arising from contaminants in radioactive beams can be addressed by using particle-$\gamma$ coincidence techniques along with heavy recoil identification in inverse kinematics. A device to accomplish these tasks is Gammasphere ORRUBA: Dual Detectors for Experimental Structure Studies (GODDESS),\footnote{D. Pain, AIP Advances 4, 041015 (2014) and references therein.} currently being commissioned for the ATLAS facility at ANL. We are currently building a compact, tilted grid ionization chamber for GODDESS to detect and identify beam-like recoils near zero degrees in the lab. The tilt (30 degrees off normal to the beam) helps the ion pairs to be detected quickly, after drifting only a short distance away from the beam axis. This reduces the response time, allowing counting rates of $\sim$500,000/s.\footnote{Pain (2014)} The design and current status of the project will be presented. Research supported by the U. S. DOE.   

TOF-counter calibration for spectroscopy experiment of pionic atoms at RIBF

We used the $^{122}$Sn(d,$^{3}$He) reaction at T$_{d}=$500 MeV to measure the binding energy of $^{121}$Sn and pion at RIKEN RIBF. To identify $^{3}$He and determine its momentum, we installed TOF-counters and MWDCs at the focal planes of BigRIPS. The TOF-counters worked as particle identifier and triggered the MWDCs, and the MWDCs enabled us to detect the incident position of $^{3}$He. The TOF-counters consisted of two groups set in upper (F5-counter) and lower (F7) streams. The F5-counter, which worked under severe rate environment, was segmented into two pieces of plastic scintillators (240*45*3.2 mm) with two PMTs on left and right edges. We conducted F5-counter calibration by using a $^{90}$Sr source to get the ideal gain by setting a proper impressed voltage to the PMTs, so that we could successfully distinguish $^{3}$He from intense backgrounds of proton and deuteron by determining an appropriate discriminator threshold.   

Production of drip-line nuclei at RIKEN RI Beam Factory

Production cross-sections and secondary-beam yields of very neutron rich nuclei near neutron drip-line at 200-250MeV/u have been investigated at RIKEN RI Beam Factory (RIBF). RIBF is the next generation RI beam facility, which can produce a variety of exotic nuclei with high intensity. The measurement of production yields of ${}^{19}$B, ${}^{22}$C, which are located on the neutron drip-line, and neighboring isotopes was made on the occasion of the Coulomb and nuclear breakup experiments of these halo nuclei at SAMURAI (Superconducting Analyzer for MUlti-particle from RAdioIsotope beams) facility at RIBF. We used 345MeV/u ${}^{48}$Ca beam as primary beam, which impinged on 30mm-thick Be target, to obtain secondary beams by projectile fragmentation. The projectile fragments were then separated through Superconducting RI beam separator BigRIPS, and were identified by measuring time of flight (TOF), energy loss ($\Delta E$), and magnetic rigidity ($B\rho$) by the standard detectors at 2nd stage of BigRIPS. We thus obtained production cross-sections and yields of carbon and boron isotopes. The production cross-sections and yields extracted were compared with the simulation code LISE using EPAX. We discuss these results and comparisons in this poster presentation.   

Test of multi-wire drift chambers for the precision spectroscopy of pionic atoms at RIBF

We conducted a spectroscopy experiment of the pionic atom in the $^{122}$Sn(d,$^{3}$He) reaction at the RIKEN RIBF in June 2014. We had two sets of multi-wire drift chamber (MWDC) on focal plane at BigRIPS and measured precisely $^3$He hit positions. Each MWDC consisted of 8 layers (X-X$'$-X-X$'$-U-U$'$-V-V$'$) and each layer had 48 sense wires every 5mm. Before the experiment, we tested them by electrons from a $^{90}$Sr source placed in front of the chamber. A scintillator placed behind the chamber provided trigger signals. Timing information was converted into drift lengths on each plane, and hit positions were calculated on the base of wire position data. Applying the least square fitting for them, 3D tracks were reconstructed, and proper operation of MWDCs was successfully confirmed in the test.   

Performance test of the Gd$_3$Al$_2$Ga$_3$O$_{12}$ (GAGG) scintillator for the nuclear astrophysics experiment

The $\gamma$-decay widths of the excited states in $^{12}$C are very important quantities to understand the nucleosynthesis in the universe, but the $\gamma$-decay widths for the $3^-_1$ and $2^+_2$ states in $^{12}$C have never been measured. To determine the $\gamma$-decay widths of the $3^-_1$ state, we propose to measure the $^1$H($^{12}$C, $^{12}$C*p) reaction under the inverse kinematics condition. The energies and emission angles of the scattered $^{12}$C and the recoil proton will be measured by the magnetic spectrometer Grand Raiden and the Si-CsI counter telescope, respectively. We carried out a test experiment at RCNP, Osaka and found that the energy resolution of the CsI detector is poorer than expected due to the high counting rate. To solve the pile-up problem in the recoil proton detector, we have started the performance test of the Ce-doped Gd$_3$Al$_2$Ga$_3$O$_{12}$ (GAGG) scintillator. The Ce-doped GAGG was recently developed and it has better light output and shorter scintillation decay time than CsI. In the present talk, the results of the performance test of the Ce-doped GAGG scintillator will be reported.   

Systematic measurement of the optical potential for the alpha elastic scattering

Alpha inelastic scattering is one of the most widely used probes to measure the isoscalar excitation strengths in atomic nuclei. Very recently, the alpha inelastic scattering from self-conjugate $N=Z$ nuclei at $E_\alpha = 130$~MeV were measured. In the recent work, the optical potentials for the elastic scattering were used in the DWBA analysis. The optical potentials were determined so as to reproduce the differential cross sections for the elastic scattering. However, the optical potentials were not uniquely determined because the experimental data of the elastic scattering was limited to the forward angles of $\theta_{lab} < 30^\circ$. Therefore, the systematic uncertainties due to the ambiguities in the optical potentials still remain in the deduced excitation strengths. In the present work, the differential cross sections for the elastic scattering at the backward angles $(\theta_{lab}=30-45^\circ)$ were measured in order to uniquely determine the optical potentials by using a 130-MeV $\alpha$ beam accelerated by AVF cyclotron at RCNP, Osaka. As the result, we succeeded in the unique determination of the optical potentials. These potentials are useful to reduce the systematic uncertainties in the isoscalar excitation strengths measured by alpha inelastic scattering.   

Study of the pure double folding optical model for 100 MeV/u deuteron scattering

The centroid energies of the giant monopole resonance (GMR) in nuclei are important because they are directly related to the nuclear incompressibility, an important quantity in the nuclear equation of state. It is necessary to examine the properties of the GMR in nuclei far from stability using advanced experimental techniques. The optical model for deuteron scattering is important from the point of view of performing these studies in inverse kinematics. Most studies on deuteron optical potentials have been done at lower energies and using the phenomenological optical model. However this model has been shown to overestimate the cross-sections for the low-lying discrete state. Recent developments in theory allow for the optical model real and imaginary volume potentials to be calculated using a double folding model with the help of the computer code dfpd5. For the first time these calculations are used to model the elastic and inelastic angular distributions in $^{28}$Si, $^{58}$Ni, and $^{116}$Sn nuclei. The experiment was performed at the Research Center for Nuclear Physics, Osaka University, Japan, using a $100$ MeV/u deuteron beam. Results of the analysis will be presented.   

Technical Developments in the Search for a Short-Range Spin-Dependent Fifth Force Interaction

Theoretical treatments of the possible interactions between two fermions from boson exchange in the nonrelativistic limit\footnote{B. Dobrescu and I. Mocioiu, J. High Energ. Phys. 2006.11 (2006): 005.} include a short-range monopole-dipole interaction proportional to $\vec{S} \cdot \vec{r}$. This potential would generate an NMR frequency shift in an ensemble of polarized nuclei when an unpolarized mass is brought nearby.\footnote{M. Bulatowicz et al, Phys. Rev. Lett. 111, 102001 (2013).}$^,$\footnote{P.-H. Chu et al, Phys. Rev. D 87, 011105(R) (2013).} Techniques to move the mass as close to the polarized nuclei as possible are needed to access sub-millimeter interaction ranges. We describe the preparation of nonmagnetic test masses and a mechanical system to bring the test mass close to an ensemble of polarized $^{3}$He nuclei, which are polarized in a spin-exchange optical pumping cell at Duke University. We describe how the masses are prepared to conform to the slightly asymmetric contours of the 100-micron thick glass cell window by a combination of coordinate measuring machine data and a spring-loaded suspension system that allows the mass to slightly rotate.   

Development of Nonmagnetic Materials for Spin-Dependent Fifth Force Searches

Theories beyond the Standard Model predict the possible existence of a spin-dependent force between polarized and unpolarized masses proportional to $\hat{S} \cdot \hat{r}$, called the ``monopole-dipole'' force in the literature [1]. Experiments that introduce a nonmagnetic mass close to and far from an ensemble of polarized nuclei and search for NMR frequency shift have set the best limits on neutron monopole-dipole interaction with matter in the range of 1 cm to several microns [2]. We are investigating various means of reducing systematic error in experiments of this type stemming from the finite magnetic susceptibility of the moving mass. We have designed a teflon container with a thin teflon membrane which can move liquid gallium in an inert atmosphere and with the slightly acidic environment required to suppress oxidation which causes gallium to stick to surfaces. We have also hot-pressed mixtures of two materials with high nucleon densities and opposite signs of magnetic susceptibility (tungsten and bismuth powders) in proportions chosen to give a magnetic susceptibility near zero at room temperature. We will present the results of these investigations. \\[4pt] [1] J. Moody and F. Wilczek, Phys. Rev. D (1984).\\[0pt] [2] P. Chu et al, Phys. Rev. D {87}, 011105(R) (2013).   

Progress in thermal neutron radiography at LENS

An end station for thermal neutron radiography and tomography is in operation at the Indiana University LENS facility. Neutrons from proton-induced nuclear reactions in Beryllium are moderated and collimated into a beam which is attenuated by a scanned object on a remotely-controlled rotating table. Neutron signal is then converted to a light signal with a ZnS scintillating screen and recorded in a cooled CCD. The author has performed diagnostics on the radiography hardware and software and has tested the system's capabilities by imaging a stack of high density polyethylene cubes with diverse inlet holes and grooves on an 80/20 aluminum base. The resolution of the radiographs are seen to be less than 1mm and 3D rending software is capable of reconstructing the internal structure of the aluminum.   

Development of an improved active gas target design for ANASEN

The Array for Nuclear Astrophysics and Structure with Exotic Nuclei (ANASEN) is a charged particle detector array with an active gas target-detector capability for sensitive measurements using radioactive ion beams. One of the main goals is to improve our understanding of nuclear reactions important in stellar explosions. Following initial experimental campaigns with ANASEN, we have been developing an improved active gas target design for ANASEN that incorporates an innovative cylindrical gas ionization detector for heavy ions surrounding the beam axis inside of the other ANASEN charged particle detectors. The detection of heavy ions in coincidence with lighter ions in a redesigned proportional counter will provide greater discriminating power. The new active gas target design will be presented, and its simulated performance will be compared with test data.   

Transition Strengths in $^{67}$Ga

High-spin states in $^{67}$Ga were studied using the $^{55}$Mn($^{18}$O,$\alpha$2$n$) reaction at 50 MeV performed at Florida State University. Prompt $\gamma$-$\gamma$ coincidences were measured with a Compton-suppressed Ge array consisting of three Clover detectors and seven single-crystal detectors. The existing level scheme was verified based on the measured $\gamma$-$\gamma$ coincidences. Lifetimes of 13 excited states were measured using the Doppler-shift attenuation method. Reduced electric quadrupole transition rates $B$($E2$) were calculated from the lifetimes and compared with the predictions of the Interacting Boson-Fermion Plus Broken Pair Model (IBFBPM) from previous work. The evolution of shape with spin was inferred from cranked Woods-Saxon calculations.   

Search for Tetrahedral Symmetry in $^{70}$Ge

The even-even Ge isotopes have recently become an active testing ground for a variety of exotic structural characteristics, including the existence of tetrahedral symmetry (pyramid-like shapes). Although theoretical shape calculations predict the onset of tetrahedral symmetry near $^{72}$Ge, the experimental signatures (including vanishing quadrupole moments within high-spin bands) remain elusive. This study searched for possible experimental evidence of tetrahedral symmetry in $^{70}$Ge. Excited states in $^{70}$Ge were populated at Florida State University using the $^{55}$Mn($^{18}$O,p2n) fusion-evaporation reaction at 50 MeV. Prompt $\gamma$-$\gamma$ coincidences were measured with a Compton-suppressed Ge array consisting of three Clover detectors and seven single-crystal detectors. The existing level scheme was enhanced through the addition of 20 new transitions and the rearrangement of five others based on the measured coincidence relations and relative intensities. Lifetimes of 24 states were measured using the Doppler-shift attenuation method, from which transition quadrupole moments were inferred. These results will be compared with those obtained from cranked Woods-Saxon calculations.   

Transition Strengths in $^{70}$As

High-spin states in $^{70}$As were produced at Florida State University through the $^{55}$Mn($^{18}$O,$3n$) reaction at 50 MeV. Prompt $\gamma$-$\gamma$ coincidences were measured with a Compton-suppressed Ge array consisting of 3 Clover and 7 single-crystal detectors. An enhanced level scheme was developed from the coincidence relations and relative intensity measurements. Spin assignments were based on directional correlation of oriented nuclei ratios. Lifetimes were determined using the Doppler-shift attenuation method. Transition quadrupole moments inferred from the lifetimes will be compared with those predicted from cranked Woods-Saxon calculations, which indicate near-prolate collective structures competing with single-particle excitations in the lowest positive- and negative-parity bands.   

Unbound Resonances in Light Nuclei

Currently there has been no comprehensive study undertaken to compile experimental results from neutron unbound spectroscopy using invariant mass measurements, gamma resolutions, and half-lives. At Central Michigan University, Hampton University, and the NSCL, a project was initiated to catalog all unbound resonances in light nuclei (Z$=$1-12). Unbound resonances were characterized by having a confirmed neutron decay branch and/or an energy level greater than the neutron binding energy listed for that isotope according to either the National Nuclear Data Center's Evaluated Nuclear Structure Files or Experimental Unevaluated Nuclear Data List and the referred journals therein. Unbound resonances will be presented for twelve elements: H, He, Li, Be, B, C, N, O, Fl, Ne, Na, and Mg. The isotopes in which unbound resonances occur will be identified, along with unbound energy levels for these isotopes. If known, each unbound resonance's gamma resolution, half-life, method of production and journal reference were also determined and a selection of these will be presented.   

Detector Calibrations for Fragmentation Reactions with Relativistic Heavy Ions at the NSCL

Prefragmentation dynamics, when neutron-rich beam nuclei interact with reaction target nuclei, have not been the subject of much experimental study. Recent data taken at the National Superconducting Cyclotron Laboratory (NSCL), in an experiment to further understand prefragmentation processes, is currently being analyzed. To experimentally determine the momentum distributions of the charged fragments made after the prefragmentation interaction between a $^{32}$Mg beam and a $^{9}$Be reaction target, the charged fragments' velocity vectors must be known. Four detectors give us position information, and two others give us energy. I worked on calibrating the four position detectors for this experiement.   

Decay Energies for 24O $\rightarrow$ 23O + n using MoNA-LISA-Sweeper Detector Systems and Monte Carlo Simulations

The LISA Commissioning experiment, conducted at NSCL at Michigan State University, used the Modular Neutron Array (MoNA) and the Large multi-Institutional Scintillator Array (LISA) in conjunction with the Sweeper Magnet and Detector Chamber, in order to investigate unbound excited states of $^{24}$O produced by proton knockout from a secondary $^{26}$F beam. Experimental energy spectra for the $^{24}$O $\rightarrow$ $^{23}$O + n decays were obtained through invariant mass spectroscopy using neutron and charged fragment trajectories and energies following decay. GEANT4-based Monte Carlo simulations, which included MENATE\_R for modeling neutron scattering, and STMONA developed by the MoNA group at NSCL, were used to take into account specific reaction dynamics and geometry, as well as all detector acceptances and efficiencies, in order to extract individual decay energies and widths from our experimental data. Results for this decay will be presented.   

Electron Capture in Core Collapse Supernovae

In stars with mass $M \geq \approx 8 M_{\odot}$, core collapse supernovae occur when the mass of the core reaches the Chandrasekhar Limit. This collapse is followed by a ``bounce,'' after which the star explodes and completes the type II supernova process. Just before bounce, electron degeneracy pressure in the star's core is removed through electron capture. Low entropy levels in the star cause electron capture on heavy nuclei to affect the supernova much more strongly than capture on free protons, which makes understanding the weak reaction rates of stellar nuclei essential to characterizing the core collapse process (Langanke et al, ``Electron capture rates on nuclei and implications for stellar core collapse''). We combine two programs, NuLib and GR1D, which respectively provide a library of neutrino interaction rates and a hydrodynamic simulation of stellar collapse, to study the consequences that varying weak reaction rates have on the supernova process. In doing so, we find groups of nuclei that contribute most strongly to the core collapse process, and better understand the level of certainty needed for accurate astrophysical modeling. This work allows us to advise for and against experimental efforts on nuclei in order to use resources as efficiently as possible.   

A Statistical Analysis of Background Contributions for Experiments Measuring Neutrinoless Double Beta Decay

Large-scale experiments are underway to observe the neutrinoless double-beta decay of $^{\mathrm{76}}$Ge with a respective energy of 2039.0-keV. A 2040.7-keV $\gamma $ ray from the 69$^{\mathrm{th}}$ excited state of $^{\mathrm{76}}$Ge could create false signals in the $^{\mathrm{76}}$Ge-enriched detectors used in these experiments. It is therefore crucial to estimate the background contribution of this 2040.7-keV $\gamma $-line. A recent experiment performed at the National Superconducting Cyclotron Laboratory was able to populate the energy state of interest and observe the 2040.7-keV $\gamma $-line. The present work focuses on the statistical analysis of this experiment in order to determine the branching ratio of the 2040.7-keV $\gamma $ ray from the 69$^{\mathrm{th}}$ excited state of $^{\mathrm{76}}$Ge. This branching ratio is to be applied to experiments attempting to observe 0$\nu \beta \beta $ events. Successful observations of 0$\nu \beta \beta $ events would be the best way to obtain the mass of the neutrino and determine its nature as a Dirac or Majorana fermion.   

Inverse-kinematics proton scattering and analysis of $^{54}$Ti and $^{56}$Ti

In May 2014, several inverse-kinematics proton scattering measurements were made by the Ursinus College nuclear structure group at the Coupled-Cyclotron Facility at the National Superconducting Cyclotron Laboratory at Michigan State University. A stable $^{76}$Ge primary beam was fragmented, which produced a ``cocktail beam'' of fifty different nuclei. This resulting beam of nuclei passed through the Ursinus College Liquid Hydrogen Target. When the beam nuclei hit the protons in the Liquid Hydrogen Target, they became excited and emitted gamma rays which we collected with the GRETINA gamma ray tracking array. In the present work, we focus on measurements of $^{54}$Ti and $^{56}$Ti and implications for the possible shell closures at $N = 32$ and $N = 34$.   

Fragment yield corrections in tin-tin collisions

In nuclear collisions that occur at the NSCL and FRIB, many different species of nuclei are produced. Most of these nuclei are stripped of all the electrons but some still have electrons attached. They will be misidentified in a mass spectrometer and the yield of other fragments will be affected. In my research, we compare the yields of fragments produced in the collisions of different Sn isotopes which have same number of protons but different number of neutrons. Such measurements help us to study the differences in the interactions of neutrons and protons, which is important in our understanding of very neutron rich objects such as the neutron stars. The S800 mass spectrograph is used to identify different fragments produced in these Sn reactions at 70 MeV per nucleon. We show that the hydrogen-like fragments contaminate mainly the yields of isotopes with two extra neutrons. Then we use the algorithm GLOBAL to estimates of the contamination fractions of each fragments to obtain correct yields for fragments we want to measure. Contamination fractions depend on the velocity of the particles but most of them are small values. In this poster, I will present how we estimate the effects of contamination fractions on the fragment yield and the physics results we obtain.   

Inverse-kinematic proton scattering from $^{52}$Ca and Implications for the GRETA Array at FRIB

The GRETINA gamma-ray tracking array is used to map the nuclear structure of unstable isotopes at Argonne National Laboratory, Lawrence Berkeley National Laboratory, and the NSCL at Michigan State University. GRETINA consists of 28 germanium crystals each packaged in 7 clusters of four crystals, which are capable of measuring the gamma rays given off by unstable nuclei. GRETINA is the first stage of the planned GRETA array, which will consist of 30 clusters rather than 7. We present a recent inverse-kinematics proton scattering measurement of $^{52}$Ca carried out at the NSCL in May 2014. We illustrate the power of the full GRETA array at the planned Facility for Rare Isotope Beams (FRIB) by comparing this measurement with simulations of a similar measurement with GRETA at FRIB.   

Laser system for collinear laser spectroscopy on neutron-deficient potassium isotopes

Nuclear moments and charge radii of neutron-deficient potassium isotopes, 35, 36, 37K, were investigated to study nuclear structure near proton dripline. The experiment was performed at the BEam COoling and LAser spectroscopy facility (BECOLA) at NSCL at MSU. Low energy radioactive ion beams were transported to BECOLA and laser light was collinearly overlapped with the ion beam. I was responsible for setting up the laser light for collinear laser spectroscopy (CLS) as well as ion beam polarization using an optical pumping technique. The laser light profile was adjusted by a telescope to be weakly focused along the 5-m long beam line with a 1 mm diameter at the detection region (a cooled PMT), which was verified using a CCD camera. A quarter wave plate was used to convert linearly polarized laser light into circularly polarized light, which was verified by measuring power variation after a polarizer. The optimum conditions for the laser system were determined by performing CLS on an offline 39K beam. The results of the offline tests as well as the online experiment will be reported.   

Implementation of Stored Waveform Inverse Fourier Transform at the LEBIT Facility

Penning traps are one the most important recent developments in mass spectrometry, and have been used successfully in the study of stable particles and short-lived, rare isotopes. The Low Energy Beam and Ion Trap facility (LEBIT) at NSCL was the first to implement Penning trap mass spectrometry at a high-energy, rare-isotope facility using projectile fragmentation. LEBIT was designed to be efficient and sensitive in order to make optimal use of the most exotic beams available at NSCL. Contaminant isotopes of similar masses also enter the trap and need to be identified and cleaned before recording data. To optimize experimentation time the stored waveform inverse Fourier transform (SWIFT) was implemented to quickly clean contaminants from the trap. This method removed the need to individually identify specific contaminants by application of a broadband cleaning RF excitation. The ion of interest will only respond to a very narrow band excitation, and every contaminant will be cleaned by applying an RF field at all other frequencies. This study was carried out to characterize the application of SWIFT to high-precision Penning trap mass spectrometry. In offline tests with $^{39}$K ions, a resolving power of 7,400 was demonstrated and resolving powers of $>10^5$ are possible.   

The Effects of Nonlocality in the DOM

Due to the instability of exotic nuclei, nuclear reactions are often utilized to study their structure. Given that the form of the nuclear potential is not yet known, effective interactions and simplifications are often employed, which can introduce large uncertainties in the theoretical models. One such simplification is the inclusion of nonlocality through a correction factor to a local equivalent potential; however, the use of this method has previously been proven inadequate. In this work, the effects of nonlocality in the dispersive optical model are considered in the bound and scattering states as well as in (p,d) transfer cross sections. To accomplish this, we conducted a systematic study of \textsuperscript{40}Ca at 20, 35 and 50 MeV in which nonlocality was accounted for explicitly in the entrance channel and through the distorted wave Born approximation for transfer. We found that the inclusion of nonlocality in the bound states had a significantly greater effect than that of nonlocality in the scattering states. In addition, nonlocality in both states lead to non-negligible differences in transfer cross sections. These results reiterate the importance of using an exact solution of the nonlocal equation rather than a local equivalent or a corrected local solution.   

Modeling and Analysis of Ultrarelativistic Heavy Ion Collisions

High-energy collisions of heavy ions, such as gold, copper, or uranium serve as an important means of studying quantum chromodynamic matter. When relativistic nuclei collide, a hot, energetic fireball of dissociated partonic matter is created; this super-hadronic matter is believed to be the quark gluon plasma (QGP), which is theorized to have comprised the universe immediately following the big bang. As the fireball expands and cools, it reaches freeze-out temperatures, and quarks hadronize into baryons and mesons. To characterize this super-hadronic matter, one can use balance functions, a means of studying correlations due to local charge conservation. In particular, the simple model used in this research assumed two waves of localized charge-anticharge production, with an abrupt transition from the QGP stage to hadronization. Balance functions were constructed as the sum of these two charge production components, and four parameters were manipulated to match the model's output with experimental data taken from the STAR Collaboration at RHIC. Results show that the chemical composition of the super-hadronic matter are consistent with that of a thermally equilibrated QGP.   

Simulation of Statistical Neutron Capture Processes Using Monte Carlo Methods with TALYS

The rapid neutron capture process (r-process) is thought to be responsible for the synthesis of about half of the nuclear species heavier than Fe. Calculations for the r-process suggest the \(^{130}\)Sn\((n,\gamma)^{131}\)Sn reaction rate plays a pivotal role in nucleosynthesis, engendering global effects on isotopic abundances over a wide mass range during the freeze-out epoch following \((n,\gamma) \rightleftharpoons(\gamma,n)\) equilibrium. This is owing, in part, to the long \(\beta\)-decay lifetime of \(^{130}\)Sn (162 s). Direct neutron capture (DC) is likely the dominant reaction at late times in the r-process near the N=82 closed shell, but the reaction rate and nucleosynthesis calculations require \((n,\gamma)\) cross sections for both DC and statistical capture. The latter depend heavily on the level density, and that is not yet well established for \(^{131}\)Sn. In order to acquire better estimates of the statistical contribution in the doubly magic \(^{132}\)Sn region, we have undertaken Monte Carlo methods of varying the nuclear reaction model parameters to calculate \((n,\gamma)\) cross sections for a range of incident neutron energies using the code TALYS. Results will be presented. Research supported by the U. S. Department of Energy.   

Beam-Normal Asymmetry of Pion Electroproduction in the Delta(1232) Region

We made theoretical calculations of the normal beam spin asymmetry in the reaction $ep \rightarrow e'\Delta(1232)$. The $\Delta(1232)$ is a nucleon excited state with spin-$\frac{3}{2}$, and decays rapidly into a proton or neutron plus a corresponding pion. The normal beam spin asymmetry has the incoming electron polarized perpendicular to the scattering plane, and is defined as $A_n=\frac{N_R-N_L}{N_R+N_L}$, where $N_R$ $(N_L)$ is the number of electrons scattered in the positive (negative) direction relative to $\hat{p} \times \hat{s}$, where $\hat{p}$ is the unit vector in the direction of the electron's momentum and $\hat{s}$ is the unit vector in the direction normal to the scattering plane. The normal beam asymmetry is small and proportional to the electron mass, and is present even in the one-photon exchange approximation. There is experimental data on $A_n$ available as a byproduct of the $Q_{weak}$ experiment, though the relevant formulas are not present in the literature. We have derived the formulas, and have evaluated them in terms of the standard multipole amplitudes, which are the basic amplitudes for pion electroproduction, $ep \rightarrow e' \pi N$ (including $\Delta(1232)$ production and subsequent decay).   

Towards a New Approach to Dual Resonance Model Phenomenology

We have taken steps toward finding a dual-resonance (DR) model appropriate for phenomenological fits that can be built from an DR operator formalism which is attractive for its projective group gauge symmetries and factorization properties. This is done by attempting to generalize an approach [Szczepaniak, Adam, and Pennington, M.R., Application of the Veneziano Model in Charmonium Dalitz Plot Analysis, arxiv:1403.5782] of isolating DR poles by making all but one of the residues of on infinite sum of modified beta functions vanish. This leaves a closed-form amplitude that has a finite set of adjustable parameters and with only one ad hoc modification necessary for maintaining Regge asymptotic behavior. We have generalized this approach to double and single Regge limits of the DR five-point function with a pending application to $p\gamma^*\rightarrow K^+K^-p$. Generalizations for $(N-3)$-tuple Regge limits for N-point amplitudes can be gleaned from this work but a more rigorous treatment has been considered. Preliminary results suggest that these amplitudes may take the form of an expectation value of an infinite sum of an alternating product of vertex operators and Gervais-Neveu propagators.   

Developing integration and extrapolation methods for no-core configuration interaction calculations

A study of the states of light nuclei in the no-core shell model is limited by the size of basis for which calculations are possible, but the results for small, calculable bases can be extrapolated to larger basis size. To understand the properties of this extrapolation, one-dimensional models in the harmonic oscillator and Coulomb-Sturmian bases are explored because of the relative ease of calculations. Using a linear algebra approach to solving Schrodinger's equation, the wave function can be determined in these models and observables such as energy and radius can be calculated. However, the integrals required for this process become cumbersome to evaluate using standard numerical methods for large basis size even in the one-dimensional model. Alternate numerical techniques are tested to determine the most effective in extending the calculations to larger basis size, and extrapolation methods within the model are explored.   

Coupling Algorithm for $\mathrm{Sp}(3,R)$ Irreducible Representations

The nuclear symplectic model based on $\mathrm{Sp}(3,R)$ -- the smallest algebra that contains both the shell model Hamiltonian and the rotor algebra -- connects the microscopic shell model to collective rotational behavior and naturally extends the Elliot $\mathrm{SU(3)}$ model to multiple shells. However, $\mathrm{Sp}(3,R)$ is only an approximate symmetry of the nucleus, where the symmetry can be broken by spin-orbit interactions, tensor force interactions, and pairing. The Hamiltonians in most physical situations will the break $\mathrm{Sp}(3,R)$ symmetry, causing their eigenstates to become linear combinations of symplectic irreducible representations (irreps). Calculations with those eigenstates will then involve multiple irreps. We report a computer algorithm for coupling symplectic irreps that should assist in performing such multi-irrep calculations and facilitate computing symplectic coupling coefficients.   

Natural orbitals for a two-particle system in one dimension as a testbed for use in the nuclear many-body problem

Natural orbitals have been applied in atomic and molecular electronic-structure theory to increase the accuracy of calculations of observables for a many-particle system. However, unlike the electron-structure problem, the nuclear problem is translationally invariant. We created a testbed code to test the usefulness of natural orbitals as they may apply to translationally invariant problems. The relative Hamiltonian matrix of a two-particle system in one dimension is first calculated in a basis of antisymmetrized products of the harmonic oscillator eigenfunctions. The natural orbitals are then calculated for the resulting ground state, and the Hamiltonian matrix is recalculated using a two-particle basis built from the natural orbitals. The effect of basis size on the accuracy of the ground state energy calculation is explored.   

A generalized framework for nucleosynthesis calculations

Simulating astrophysical events is a difficult process, requiring a detailed pairing of knowledge from both astrophysics and nuclear physics. Astrophysics guides the thermodynamic evolution of an astrophysical event. We present a nucleosynthesis framework written in Fortran that combines as inputs a thermodynamic evolution and nuclear data to time evolve the abundances of nuclear species. Through our coding practices, we have emphasized the applicability of our framework to any astrophysical event, including those involving nuclear fission. Because these calculations are often very complicated, our framework dynamically optimizes itself based on the conditions at each time step in order to greatly minimize total computation time. To highlight the power of this new approach, we demonstrate the use of our framework to simulate both Big Bang nucleosynthesis and r-process nucleosynthesis with speeds competitive with current solutions dedicated to either process alone.   

Monte Carlo simulations for analysis and design of nuclear isomer experiments

The well-established GEANT4 Monte Carlo code was used to analyze the results from a test of bremsstrahlung-induced nuclear isomer switching and to guide development of an experiment to test nuclear excitation by electron capture (NEEC). Bremsstrahlung-induced experiments have historically been analyzed with the assumption that the photon flux of the bremsstrahlung spectrum at a given energy varies linearly with the spectrum's endpoint. The results obtained with GEANT4 suggest that this assumption is not justified; the revised function differs enough to warrant a re-analysis of the experimental data. This re-analysis has been applied to the switching of the unusually long-lived isomer of $^{\mathrm{180}}$Ta (T$_{\mathrm{1/2\thinspace }}$\textgreater 10$^{\mathrm{16}}$ yr.), showing that the energies of its switching states differ by about 30 keV compared to those previously identified. GEANT4 was also employed in the design of a NEEC experiment to test the isomer switching of $^{\mathrm{93}}$Mo via coupled atomic-nuclear processes. Initial work involved modeling a beam of $^{\mathrm{93}}$Mo ions incident on a volume of $^{\mathrm{4}}$He gas and observing the charge exchange process and associated emitted fluorescence. The beam and $^{\mathrm{4}}$He volume, the ionization trails of the electrons liberated from the $^{\mathrm{4}}$He atoms, and the subsequent fluorescence were successfully simulated; however, it was found that GEANT4 does not currently support ion charge exchange. Future work will entail either the development of the requisite code for GEANT4, or the use of a different model that can accurately simulate ion charge exchange.   

Maximum J Pairing and Asymptotic Behavior of the 3j and 9j Coefficients

We investigate the large $j$ behavior of certain $3j$ and $9j$ symbols, where $j$ is the total angular momentum of one particle in a given shell. Our motivation is the problem of maximum $J$ pairing in nuclei, along with the more familiar $J=0$ pairing. Maximum $J$ pairing leads to an increase in $J=2$ coupling of two protons and two neutrons relative to $J=0$. We find that a coupling unitary $9j$ symbol ($U9j$) is very weak as $j$ increases, leading to wavefunctions which are to an excellent approximation single $U9j$ coefficients. Our study of the large $j$ behavior of coupling unitary $9j$ symbols is through the consideration of the case when the total angular momentum $I$ is equal to $I_{\mathrm{max}}-2n$ and $I_{\mathrm{max}}\equiv4j-2$, where $n=0,1,2,...$. We here derive asymptotic approximations of coupling $3j$ symbols and find that the $3j\propto j^{-3/4}$ in the high $j$ limit. One major analytical tool we used is the Stirling Approximation. Through analytical, numerical, and graphical methods, we show the power law behavior of the coupling unitary $9j$ symbols in the $n/j\ll1$ limit, i.e. $U9j\propto j^{-n}$. Power-law behavior is evident if there is a linear dependence of $\ln{|U9j|}$ vs. $\ln{j}$. We also present some examples of percent errors in our approximations.   

Determination of lifetimes by the Doppler Shift Attenuation Method on a multilayer target using the program package LINESHAPE

The lifetimes of low lying levels in $^{92,96}$Ru and $^{72}$Ge were remeasured. The projectiles were Coulomb excited in inverse kinematics on a target consisting of a carbon (or magnesium) layer deposited on a gadolinium (or iron) foil followed by a copper backing designed for magnetic moment measurements. The setup consisted 4 HPGe clover detectors located around the target so as to obtain forwards and backwards Doppler shifts of the detected $\gamma$ rays. Each clover consists of 4 independent Ge crystals which were treated as independent detectors. The energy spectra of $\gamma$ rays de-exciting the levels of interest were examined using the program LINESHAPE by Wells and Johnson [1]. The program package consists of a Monte Carlo simulation of the energy loss of the projectiles passing through the target. Then the velocity histories are converted into velocity profiles as seen by each particular detector. Subsequently, the calculated line shapes are fitted to the experimental data using the minimization and error analysis contained in Minuit. In this work the effects of different representations of $\frac{dE}{dx}$ and detector arrangements were investigated. Findings will be presented. \\[4pt] [1] J.C. Wells and N.R. Johnson, ``Computer code LINESHAPE'' (1999), PD-LNL version.   

High Purity Germanium Detectors and Angular Distribution of 2Al(p,g)28Si

The purpose of this research was to study high purity germanium detector systems, and to calculate and compare absorption ratios of 27Al(p,g)28Si. Work with the germanium detector online array for gamma ray spectroscopy in nuclear astrophysics in the Nuclear Science Laboratory at the University of Notre Dame, also known as Georgina, including energy calibrations and work with software and hardware logic, provided the necessary background and experience with high purity germanium detectors and angular distribution of gamma rays. The knowledge taken from work with the Georgina detectors was then applied to the analysis of 27Al(p,g)28Si. Previous experimental data of 27Al(p,g)28Si was analyzed using the Ep $=$ 1778.9 keV resonance. The data used was taken from a 2010 experiment completed in the Nuclear Science Laboratory at the University of Notre Dame using the 4MV KN particle accelerator. A 1977 paper by A. Anttila and J. Keinonen with analysis of the same reaction using the Ep$=$ 992 keV resonance was used for the energy calibration and gamma energies. Peak fitting and background reduction of the spectra were completed using analysis software, jtek. Angular distribution ratios from a 56Co source were used for the normalization of the 27Al data. Angular dependent absorption factors were used to analyze the angular distribution of $\gamma$-rays from the 27Al beam target. With these absorption factors, relative gamma intensity measurements of 27Al(p,g)28Si were calculated.   

Simulating a Multi-Reflection Time-of-Flight Mass Spectrograph for the Purification of Radioactive Isobars

A Multi-Reflection Time-of-Flight mass spectrograph (MR-TOF) is being designed for the future Notre Dame Radioactive Ion Beam facility. The MR-TOF will provide isobarically pure beams to experiments. Design considerations for the MR-TOF include its geometry, its electrode voltages, and the choice of ion extraction scheme. These considerations were investigated using SIMION simulations. As a benchmark, we first optimized the electrode voltages of the ISOLTRAP MR-TOF geometry. The preliminary simulations involved varying two electrode voltages with the remaining electrodes held fixed and resulted in a mass resolving power \textless TOF\textgreater / $\Delta $TOF $\approx $ 45,000. Further simulations to optimize the~remaining~three electrodes will be required to~reach higher mass resolving power.   

Analyzing Deuteron Scattering at 100 MeV/u Through Optical Model Parameters

Nuclear incompressibility is the curvature of the equation of state of nuclear matter at saturation density. The preferred medium through which we quite effectively study and then constrain incompressibility is the isoscalar giant monopole resonance (ISGMR), one breathing mode of the nucleus. Using the nuclear optical model to both fit and reproduce elastic and inelastic scattering patterns, respectively, we can translate our calculations to the strength of the monopole and ultimately incompressibility. With the advent of radioactive beam facilities have come excellent experimental advancements. From here we begin to discern which probes are ideal for use in nuclear collisions. Deuterium is presently being tested for its feasibility. The Research Center for Nuclear Physics at Osaka University in Japan was home to just such an experiment. A 196 MeV $^{2}$H beam was impinged on $^{116}$Sn, $^{28}$Si and $^{58}$Ni targets to measure the elastic and inelastic cross-sections at various angles. These angular distributions have been analyzed using the hybrid optical model. Results of this analysis will be presented.   

Notre Dame Nuclear Database: A New Chart of Nuclides

Nuclear data is critical to research fields from medicine to astrophysics. We are creating a database, the Notre Dame Nuclear Database, which can store theoretical and experimental datasets. We place emphasis on storing metadata and user interaction with the database. Users are able to search in addition to the specific nuclear datum, the author(s), the facility where the measurements were made, the institution of the facility, and device or method/technique used. We also allow users to interact with the database by providing online search, an interactive nuclide chart, and a command line interface. The nuclide chart is a more descriptive version of the periodic table that can be used to visualize nuclear properties such as half-lives and mass. We achieve this by using D3 (Data Driven Documents), HTML, and CSS3 to plot the nuclides and color them accordingly. Search capabilities can be applied dynamically to the chart by using Python to communicate with MySQL, allowing for customization. Users can save the customized chart they create to any image format. These features provide a unique approach for researchers to interface with nuclear data. We report on the current progress of this project and will present a working demo that highlights each aspect of the aforementioned features. This is the first time that all available technologies are put to use to make nuclear data more accessible than ever before in a manner that is much easier and fully detailed. This is a first and we will make it available as open source ware.   

Measurements of Internal Conversion Electron Emission Cross-Sections for 154, 156, 157Gd

To study the nuclear structure of deformed nuclei, in particular, 0$+$ excited states in several gadolinium isotopes, we plan to perform ($\alpha $, n) and ($\alpha $, 2n) reactions on enriched samarium targets utilizing coincidence and time of flight techniques to measure conversion electrons, gamma rays and neutrons. As a preliminary experiment, natural samarium targets were used. Alpha particles, 16-21 MeV in energy, were incident upon a series of four natural samarium targets with the primary aims to measure cross sections of the selective ($\alpha $, n/2n) channels and test the targets. Data were collected via an Internal Conversion Electron Ball array (ICEBall) containing six Si(Li) detectors and accompanying neutron and gamma-ray counters. Spectra were observed in ICEBall from electrons emitted from a range of reaction channels both in ground state and excited states of gadolinium. The focus was set on ($\alpha $, n/2n) channels that were more easily observed and identified with conversion electron peaks emitted from gadolinium-154, 156 and 157. We will present the results on conversion electron emission cross-sections as well as neutron and gamma fluxes and compare with TALYS calculations. These data give insight for performing future experiments that will use enriched targets so as to allow optimum beam energy for particular reaction channels while maintaining a neutron flux that is non-destructive for HPGe detectors.   

Alignment Sensitivity Study of the St. ANA Beam Line

The St. ANA (STable Accelerator for Nuclear Astrophysics) accelerator is being prepared for use with the St. George recoil mass separator. The accelerator is in working condition for use in direct kinematic experiments but the St. George separator works with inverse kinematics and requires a highly controlled beam restricted by severe position and divergence parameters that are not achieved at the present time. A systematic sensitivity study was conducted using a simulation of the beam line in order to assess the impact of a misalignment in each optical element or in the beam itself. Tests were done with the beam to analyze how the beam behaves at various points in the line and to compare this data with simulation results to determine possible causes of misalignment. The results of these tests and simulations are that the beam characteristics are now better understood and the possible causes of the limitations have been narrowed down.   

Modernizing Plunger Control with Low-Cost Digital Electronics

The plunger technique provides a valuable tool for measuring lifetimes of excited states in the 1-100 ps range. The plunger consists of a thin foil target and stopper foil separated by some controllable distance; beam-induced reactions occur in the target and the resulting nucleus of interest leaves the target foil and is completely stopped by the stopper foil. The Notre Dame Nuclear Science Laboratory has a plunger device which is approximately 30 years old. In the Notre Dame plunger apparatus, the separation between foils is measured via capacitance between the foils and is used to control the position of three servo motors. Our work this summer focused on a complete rebuild of the plunger control electronics including two major upgrades: (1) a precision capacitance-measuring circuit based on the phase-shift of a sinusoidal signal which follows a development in the mid 1990's, (2) and a low-cost microcontroller-based feedback loop for precisely controlling servo motors with quadrature encoder outputs. After demonstrating that the upgrades are successful, we will carry out reactions in the Nuclear Science Laboratory and measure the lifetimes of excited states in several rare earth nuclei.   

AMS Radiocarbon Dating at Notre Dame

Current development of a local radiocarbon dating method using Accelerator Mass Spectrometry (AMS) at the University of Notre Dame seeks to provide sensitive, reproducible, and accurate measurements for future interdisciplinary projects. While AMS has been the premier radiocarbon dating method for a few decades, repurposing Notre Dame's FN Tandem accelerator for radiocarbon dating has provided many unique challenges. Experiments have shown radiocarbon dating possible and reproducible using the FN Tandem accelerator, found optimal settings for said accelerator, and established sensitivity limits comparable to dedicated radiocarbon dating facilities. In addition, there is ongoing work to create a local chemistry lab to convert organic artifacts into graphite samples to be dated locally. Once the chemistry side has been completed, several artifacts from the IAEA's radiocarbon intercomparison have been procured. Dating these previously studied artifacts will provide an additional measure on the accuracy and repeatability of both the accelerator and chemical treatment. Provided that these IAEA artifacts are dated successfully, exciting projects will ensue, such as the authentication of artwork and dating of anthropological samples.   

Carbon-14 Graphitization Chemistry

Accelerator Mass Spectrometry (AMS) is a process that allows for the analysis of mass of certain materials. It is a powerful process because it results in the ability to separate rare isotopes with very low abundances from a large background, which was previously impossible. Another advantage of AMS is that it only requires very small amounts of material for measurements. An important application of this process is radiocarbon dating because the rare $^{14}$C isotopes can be separated from the stable $^{14}$N background that is 10 to 13 orders of magnitude larger, and only small amounts of the old and fragile organic samples are necessary for measurement. Our group focuses on this radiocarbon dating through AMS. When performing AMS, the sample needs to be loaded into a cathode at the back of an ion source in order to produce a beam from the material to be analyzed. For carbon samples, the material must first be converted into graphite in order to be loaded into the cathode. My role in the group is to convert the organic substances into graphite. In order to graphitize the samples, a sample is first combusted to form carbon dioxide gas and then purified and reduced into the graphite form. After a couple weeks of research and with the help of various Physics professors, I developed a plan and began to construct the setup necessary to perform the graphitization. Once the apparatus is fully completed, the carbon samples will be graphitized and loaded into the AMS machine for analysis.   

Nuclear data made easily accessible through the Notre Dame Nuclear Database

In 1994, the NNDC revolutionized nuclear research by providing a colorful, clickable, searchable database over the internet. Over the last twenty years, web technology has evolved dramatically. Our project, the Notre Dame Nuclear Database, aims to provide a more comprehensive and broadly searchable interactive body of data. The database can be searched by an array of filters which includes metadata such as the facility where a measurement is made, the author(s), or date of publication for the datum of interest. The user interface takes full advantage of HTML, a web markup language, CSS (cascading style sheets to define the aesthetics of the website), and JavaScript, a language that can process complex data. A command-line interface is supported that interacts with the database directly on a user's local machine which provides single command access to data. This is possible through the use of a standardized API (application programming interface) that relies upon well-defined filtering variables to produce customized search results. We offer an innovative chart of nuclides utilizing scalable vector graphics (SVG) to deliver users an unsurpassed level of interactivity supported on all computers and mobile devices. We will present a functional demo of our database at the conference.   

Investigation of low-spin states in Sm nuclei following (p,t) reactions

The low spin structures of $^{152}$Sm nuclei were studied following the $^{154}$Sm(p,t) reactions. The 25 MeV proton beam was provided by the K150 Cyclotron at Texas A\&M University. The Silicon Telescope Array for Reaction Studies (STARS) was utilized to detect outgoing charged particles, providing for both reaction selectivity and excitation energy in the residual nucleus. The efficiency of the telescope was about 20\% for outgoing charged particles. The clover Ge detectors of the LiTeR (Livermore Texas Richmond) array measured coincident gamma rays with an efficiency of $\sim$ 5\% at 200 keV and $\sim$ 2\% at 1332 keV. The angular coverage of the STARS silicon detectors was $\sim$ 30-60 degrees allowing a measurement of the angular distribution of tritons emitted from the $^{154}$Sm nucleus. These were compared to calculated DWBA curves order to make spin assignments for levels directly populated by the reaction. The next step in this research is to begin analysis of angular distributions of the continuum region of higher excitation energies in order to determine a distribution of L-transfer values.   

Half-Lives of ground states in Pm and Eu nuclei following the $^{154,152}$Sm (p,x) reactions at 25 MeV

The primary experiment was designed to study low/medium spin states in Sm nuclei following the $^{154,152}$Sm (p,x) reactions where x = d or t. During the experiment the Sm target was irradiated by a 25 MeV proton beam, provided by the K150 Cyclotron at Texas A\&M University, with an average beam current of $\sim 1$ nA for about one week. Following the experiment, residual radioactivity in the target was measured in the Environmental Radioactivity Laboratory at the University of Richmond using a 25\% efficiency coaxial Ge detector enclosed in a 6-inch thick Pb shield. The gamma ray spectra were internally calibrated using a $^{152}$Eu source and the energies of known gamma-rays from the target decays and from long lived environmental radioactivity. The decays of three long lived ($\sim$ 1 month or more) mass A $\sim$ 150 nuclei were identified ($^{148}$Sm, $^{148}$Eu, and $^{147}$Eu), and half lives for their beta-decay were (re)measured. Work is still in progress and preliminary results will be presented at the APS conference.   

Development of a Neutron Detector for A1 at MAMI

The Mainz A1 spectrometers perform high precision measurements to investigate the structure of the nucleus and its constituents. Previous knowledge of the neutron form factor (FF) is limited due to poor detection efficiencies. Our goal is to create a neutron detector with an efficiency better than 80{\%}, leading to the improvement of the measurements of the neutron electric FF and reducing systematic uncertainties. This new detector would also open up the possibility to study non-mesonic two-body weak decays. ~The neutron detector should have a large active detector volume, a high detection efficiency (\textgreater 80{\%}), a good resolution (\textless .5 ns), and must be low in cost. The proposed design of the detector follows a modular concept with an active detector volume of approximately one cubic meter. In order to allow high beam currents and their resulting high rates, this detector will be highly segmented using 32 crossed layers consisting of 64 bars, utilizing solid and liquid organic scintillators, with dimensions (15 x 30 x 960) mm$^{3}$. In total 4096 channels have to be read out via WLS fibers using silicon multi pixel photon counters (MPPC).   

Active Helium 3/4 Target for Use in MAMI Crystal Ball

By using a Helium 3 Active target (AT) with the A2 photon beam in MAMI, the polarizability of the neutron, a value that has not yet been well defined, can be determined. In order to be used in the MAMI Crystal Ball, the size of the $^{3}$He Active Target needed to be decreased. For our experiment we tested new, compact photomultiplier tubes (PMTs) by comparing their response to changes in nitrogen admixture concentration to those of the original, larger PMTs. We also examined the contribution of NINO discriminators, to be attached to the new PMTs to decrease noise effects. We found that the new PMTs and NINO discriminator functioned well and will be used in the future experiment, though a decrease in voltage detection was experienced. Additionally, using AT Geant4, simulations of the upcoming experiment were performed and background and resolution studies conducted. We specifically examined mass loss due to quasi free Compton Scattering, $\pi_{0}$ production and the breakup of the $^{3}$He nucleus.   

Tagging Efficiency for Nuclear Physics Measurements at MAX-lab

A careful study of the tagging efficiency during measurements of near threshold pion photoproduction and high energy Compton scattering has been performed. These experiments are being done at the MAX-lab tagged photon Facility during the June 2014 run period. The determination of the final results from these experiments depends on knowledge of the incident photon flux. The tagging efficiency is a critical part of the photon flux calculation. In addition to daily measurements of the tagging efficiency, a beam monitor was used during the production data runs to monitor the relative tagging efficiency. Two trigger types were used in the daily measurements; one was a logical OR from the tagger array and the other was from the Pb-glass photon detector. Investigations were made to explore the effect of the different trigger conditions and the differences between single and multi hit TDCs on the tagging efficiency. In addition the time evolution and overall uncertainty in the tagging efficiency for each tagger channel was determined. The results will be discussed.   

Preparation of the MAX-lab LD2 Target

Experiment E08-01 at MAX-lab is being conducted in order to provide data on the near-threshold cross-section for $\pi^-$ photoproduction and high-energy nuclear Compton scattering. The experiment utilizes the MAX-lab Tagged Photon Facility and three large-volume NaI detectors to measure the high-energy gamma-rays produced from Compton scattering or from the capture of $\pi^-$ events in the target. The goal is to obtain data on these processes from the neutron for comparison with various theoretical predictions. Since a free-neutron target is not available, a liquid deuterium target will be used. MAX-lab has such a target; however, it has not been operated since 2011. The integrity of the target vessel is of paramount importance to the experiment since any leaks could result in not only contaminated data, but also a safety risk. The procedure used for preparing the target vessel will be discussed. Preparation included positioning and testing temperature sensors, removing gas contaminates, and leak-testing the target vessel. After testing, a number of problems were found, the most serious of which is a leak in the cooling head. A future course of action will be prescribed with the intention of having the target ready for its use in the continuation of E08-01 scheduled for fall 2014   

Characterization of Lead Glass Cherenkov Detectors Using Cosmic-Ray Muons

A 16 by 16 array of small lead glass Cherenkov detectors is being prepared for use in nuclear physics experiments to be performed at the Paul Scherrer Institute in Switzerland. This highly segmented array provides information on the angle (both $\theta$ and $\phi$) as well as the energy of the detected particles. It contains over 200 optically isolated lead glass detectors, each 4.2 cm by 4.2 cm and 30 cm long, which are sensitive to both charged particles and gamma rays. The characteristics of a sample of these detectors were determined by measuring the energy resolution for cosmic-ray muons traversing the detector. The typical resolution of the detectors was found to be approximately 10\% at 53.5 MeV. Details of the measurement technique and results will be presented. These results can be used as a general expectation for the remainder of the detectors in the array.   

An Energy Calibration of the CATS large NaI Detector at MAX-lab

An energy calibration for the large volume single crystal NaI detector CATS has been completed. CATS is currently located at the MAX-lab Tagged Photon Facility in Lund, Sweden and is being used for measurements of near threshold negative pion photoproduction and high-energy nuclear Compton scattering. These experiments, particularly the later, require accurate energy calibrations. To perform these calibrations the detector was placed directly in the tagged photon beam, which provides gamma rays with known energies from 145-165 MeV. The detector core is viewed by seven PMTs, and is surrounded by six segments, each of which is individually instrumented. The final output from CATS is an average of the core PMTs plus the segments PMTs to account for any energy losses from the core region. Consequently, gain matching of the core and segment PMTs as well as pedestal corrections for each PMT are required. The energy calibrations were done with two different triggers; one being from the photon tagger and the other from the detector itself; results from both will be compared. The final calibration showed a highly linear fit between the measured CATS output and the photon energies provided by the tagger with an energy resolution of approximately 2.3 MeV.   

Calibration Procedures for Large Sodium Iodide Detectors

In order to have accurate and meaningful experimental results the equipment used for measurement must be calibrated. This project is concerned with the time and energy calibrations of the large sodium iodide detector known as BUNI. The data was collected by placing BUNI directly in a beam of known energy electrons. The data was modified by a series of physically well known corrections. The exact method of calibration will be described in greater detail. The consequences of performing calibrations with different triggers types will also be discussed. This report will also show how the scripts have been amended in order to give more physically meaningful results. These calibrations were done as part of the data analysis for the ``Photoproduction of Pions'' experiment, which was done at Max-Lab in Lund, Sweden during June 2014.   

DIANA NaI-Detector Energy Calibration

The DIANA detector is being used for measurements of near threshold pion photoproduction and high-energy nuclear Compton scattering being performed at the MAX-lab tagged photon facility in Lund, Sweden. Accurate energy calibrations are essential for determining the final results from both of these experiments. An energy calibration has been performed for DIANA, a single-crystal, large-volume, NaI detector. This calibration was made by placing the detector directly in the tagged photon beam with energies from 145 to 165 MeV and fitting the detector response to the known photon energies. The DIANA crystal is instrumented with 19 PMTs, pedestal corrections were applied and the PMTs were gain matched in order to combine the readout value from each PMT and determine the final detector response. This response was fitted to the tagged photon energies to provide the final energy calibration. The calibrations were performed with two triggers; one from the detector itself and one provided by the photon tagger. The quality of the final calibration fit and the energy resolution of the detector, $\sigma \approx 2.4$ MeV, will be shown.   

Photoactivation of $^{\mathrm{176m}}$Lu via Bremsstrahlung at the Stuttgart DYNAMITRON

Though unstable, the ground state of $^{176}$Lu has a very long half-life of approximately 37 billion years and primarily $\beta ^{-}$ decays (\textgreater 99.9{\%}) to $^{176}$Hf. However, $^{176}$Lu possesses an isomer (J$^{\pi} = $ 7$^{-})$ 123 keV above the ground state (J$^{\pi} = $ 1$^{-})$ that also $\beta^{-}$ decays to $^{176}$Hf but with a much shorter half-life of about 3.6 hours. The study of this isomer could lead to new findings regarding astrophysical nucleosynthesis. A disparity between the predicted abundance of $^{176}$Lu due to nucleosynthesis and the actual measured abundance implies that transitions from the isomer to the ground state via intermediate states must have taken place during the s-process. Since the rates at which these transitions occur are temperature dependent, $^{176}$Lu could be used as an s-process ``thermometer.'' A photoactivation experiment was performed on $^{176}$Lu at the Stuttgart DYNAMITRON using bremsstrahlung with varying endpoints between 0.7 and 2.2 MeV to determine the intermediate state energies and integral cross sections for the transitions that lead to the isomer. We present the results of the analysis of the data as well as preliminary values for the intermediate state energies and their cross sections.   

The study of Sci-Fi Trigger counter for a hadron photo production experiment at SPring-8

In SPring-8, we are going to perform a hadron photo-production experiment with the new beam line by using a photon beam produced by the backward Compton scattering method. The timing of this scattering is synchronized to the interval of 2ns by RF signal in the synchrotron ring. In order to use RF signal as event start timing, we need the trigger timing with a time resolution of 300ps by using trigger counter covered with the target. Because the RF timing is very precise (15 ps) and enough to achieve high time resolution, we use RF signal for the beginning point of Time-Of-Flight measurement. In order to reduce multiple scattering, the thickness of this trigger counter should be less than 2mm. The scintillation fiber can easily change its shape and suit for this experiment. We have measured the geometric dependence of the time resolution and light intensity of scintillation fiber. We report the result of this measurement.   

Performance test of the Multi-gap Resistive Plate Chamber (MRPC) with cosmic ray

MRPC is a gaseous ionization detector, which a good timing resolution has been used practically in the nuclear and particle physics experiment. A mixed gas of SF$_6$ and Fleon 134a was flowed through the gaps between high resistive plates (500$\mu$m thickness glass). A high electric field of $\sim$2$\times10^6$ [V/m] was applied between the plates. A charged particle passes through the MRPC and causes avalanche amplification. We constructed a relatively small MRPC with a readout pad (20 mm $\times$ 50 mm). The development is motivated by feasibility study of the MRPC as a photon tagger at the Research Center for Electron Photon Science (ELPH), Tohoku University. The photon tagger needs a good timing resolution ($<$ 100 ps), therefore we studied the small size MRPC, while a large sized MRPCs are widely used in nuclear and particle experiments. The MRPC can operate under the strong magnetic field and thus it can be a good candidate as an electron detector placed in the magnet. We tested the HV dependence of time resolution of the MRPC with cosmic rays. The MRPC will be demonstrated at the open campus of the Tohoku University as an example of nuclear experimental detectors. We will measure the zenith angle and velocity distributions of cosmic ray.   

Measurement of zenith angle distribution of cosmic rays by a spark chamber

Spark chamber is a detector which developed by Fukui and Miyamoto in 1959. It visualizes tracks of charged particles. It consists of many layers of the acrylic frames with electrode plates at the top and bottom, where high voltage (6-7 kV) was put. The chamber was filled with inert gas such as helium. A spark along the trajectory of a charged particle by high voltage can be seen when internal gas is ionized by the charged particles. The chamber was designed and constructed by ourselves. Materials and gap of the electrodes were optimized and stainless steel with 1.5 cm gap were chosen. Plastic scintillation counters were placed up and down of the chamber and the signals from them were used as the trigger. The voltage to the electrode plates is applied only when the cosmic rays pass through the scintillators. The spark chamber will be demonstrated as the nuclear and particle physics experiment detector to high-school students at the open campus of our university. Furthermore, the zenith angle distribution of cosmic rays will be measured by the spark chamber. Image analysis method will be used for this measurement.   

Study of temperature dependence of a LaBr$_{3}$ crystal for high-energy-resolution $\gamma$-ray detection

We will report on a temperature dependence of an inorganic crystal scintillator for $\gamma$-ray detection, LaBr$_{3}$. The scintillators used in this measurement has different shape made by Saint Gobain, and they were coupled to the Hamamatsu photomultipliers. The temperature dependence of the photo peaks was measured by detecting 511 and 1275 keV photons from the $^{22}$Na source, taking their signals to QDC and tracing the total absorption peaks while chang of the room temperature with the daily range was measeured by a digital thermometer. After correcting the delay in the response from the temperature to the scintillators, the dependence of the gain shift on the room temperature was clearly observed. The temperature dependence must be compensated in order to obtain the intrinsic resolution of scintillators of LaBr$_{3}$.   

Two-dimensional position sensitive ionization chamber with GEM

We have been developing a multi-anode ionization chamber for Accelerator Mass Spectrometry (AMS) at Kyushu University. Furthermore, we are planning to construct a neutron detector with high position resolution by combining the chamber with Gas Electron Multiplier (GEM) and a neutron converter. One of purposes is the measurement of $(\vec{p}, pn)$ knockout reaction from unstable nuclei. The multi-anode ionization chamber is composed of subdivided multiple anodes, a cathode to produce an uniform electric field, and a Frisch grid. The chamber must have position sensitivity because obtaining a beam profile is required for AMS measurements, where counting loss should be avoided. Also in the case of the neutron detector, it is necessary to measure the position to deduce the scattering angles. We have recently established a two-dimensional position readout system by the following methods: the measurement of horizontal position is enabled by trimming some anodes into wedge-like shape, and vertical position can be determined by the ratio of induced charge on the grid to the total charge on anodes. In addition, improvement of S/N ratio is important for isotope separation and position resolution. We installed a rectangular-shaped GEM and tried improving S/N ratio by electron amplification.   

Proportional Counter Calibration and Analysis for $^{12}$C$+$p Resonance Scattering

Light exotic nuclei provide a unique opportunity to test the predictions of modern \textit{ab initio} theoretical calculations near the drip line. In \textit{ab initio} approaches, nuclear structure is described starting from bare nucleon-nucleon and three-nucleon interactions. Calculations are very heavy and can only be performed for the lightest nuclei (A\textless 16). Experimental information on the structure of light exotic nuclei is crucial to determine the validity of these calculations and to fix the parameters for the three-nucleon forces. Resonance scattering with rare isotope beams is a very effective tool to study spectroscopy of nuclei near the drip line. A new setup was developed at the Cyclotron Institute for effective resonance scattering measurements. The setup includes ionization chamber, silicon array, and an array of proportional counters. The proportional counter array, consisting of 8 anode wires arranged in a parallel cellular grid, is used for particle identification and to track the positioning of light recoils. The main objective of this project was to test the performance and perform position calibration of this proportional counter array. The test was done using $^{12}$C beam. The excitation function for $^{12}$C$+$p elastic scattering was measured and calibration of the proportional counter was performed using known resonances in $^{13}$N. The method of calibration, including solid angle calculations, normalization corrections, and position calibration will be presented.   

Determining Modern Energy Functional for Properties of Nuclei And Nuclear Matter

The development of an energy density functional (EDF) for the interacting nuclear system is very important for the study of properties of nuclei away from the valley of stability and astrophysical systems. Current literature lists over 300 EDF's based on Skryme-type nucleon-nucleon effective interactions whose parameter sets are fixed according to different ranges of experimental data, and most of which fail to predict an unbound $^{28}$O nucleus. I vary the parameters of Skryme-type nucleon-nucleon effective interaction KDE0v1 using Hartree-Fock-based approximations to obtain a new interaction KDE0v1* that leaves oxygen-28 unbound. This new interaction KDE0v1* accomplishes this while calculating binding energies consistent with a wide range of known nuclear masses. This will contribute predictions that can be used to determine properties of neutron stars and the location of the neutron dripline.   

Novel Techniques for the Position Calibration of FAUST

The Forward Array Using Silicon Technology (FAUST) consists of 68 silicon cesium-iodide telescopes, which identify and measure the energy of charged particles. In order to measure the correlation functions of light charged particles (particularly, protons) FAUST has recently been upgraded with position-sensitive silicon detectors, which will enable higher resolution in relative momentum. To get maximum benefit from the upgrade, the positions of the detectors must be accurately known. For this calibration, a tungsten mask with diagonal slits is placed in front of the array so that alpha particles from a source, or Rutherford scattered off of a gold target hit the detectors in a striped pattern. The stripes are then identified on each detector using the K-means algorithm, which can be used to identify clusters of data. They are then characterized by a simple linear fit. Once the stripes are identified, a set of linear transformations must be found which will move a simulation of ideal data to match the measured data. One possible approach to this problem is to use the Hill Climbing algorithm to find the actual position of detectors by manipulating the slopes of the lines. Prospects for this position calibration technique will be presented.   

Characterization of aerosol transport in a recoil transfer chamber for heavy element chemistry

Heavy elements (HE) are elements with Z \textgreater 103 that can be synthesized via target material bombardment by accelerated charged particles. Production and investigation of properties of new elements result in understanding of upper limit of Periodic Table of Elements. Study of chemical behavior of HE is usually based on comparison with their light homologue properties. Such experiments require transportation of elements of interest from a target chamber to a radiochemical laboratory within several seconds. Aerosol transport is a widely known way to transfer non-volatile elements in on-line experiments. This particular project is devoted to design, characterization and optimization of aerosol transport for implementation in future experiments at Cyclotron Institute, Texas A{\&}M University. Different types of aerosol generators and particle parameters such as: size distribution, concentration and charge have been considered. Results showing procedure development will be presented. *Funded by DOE and NSF-REU Program   

Extracting the Continuum Cross section in Giant Resonance Analysis

The Giant monopole resonance (GMR) is being studied through the inelastic scattering of 240 MeV $\alpha $ particles on various nuclei to better determine nuclear matter incompressibility (K$_{\mathrm{nm}}$) . Since the GMR is above particle decay thresholds, there is a continuum underlying the giant resonances which is at best poorly understood. In order to ascertain the nature of this continuum, a computer program is being developed that allows the input of assumptions about the location, distribution, and strengths of L$=$0-4 multipole distributions which are then converted to cross sections and subtracted from the experimental data at angles from 0-6$^{\circ}$. The resulting continuum for each angle and each target can then be compared to reaction models to better understand the process.   

Precise Measurements of the Internal Conversion Coefficient of $^{\mathrm{\mathbf{111m}}}$Cd Isomer

The theoretical Internal Conversion Coefficient, $\alpha_{\mathrm{K}}$, for the 150 keV E3 transition in $^{\mathrm{111m}}$Cd depends on the treatment of the atomic vacancy. If the atomic vacancy is taken into consideration, the $\alpha_{\mathrm{K}}$ value equals to 1.450, while the $\alpha_{\mathrm{K}}$ value is 1.425 when the vacancy is neglected. In an 1987 publication, the $\alpha_{\mathrm{K}}$ was determined to be 1.29 $\pm$ 0.11, which agrees with neither value. To investigate this discrepancy, we conducted an experiment to remeasure the $\alpha _{\mathrm{K}}$ of $^{\mathrm{111m}}$Cd. By using a 99{\%} enriched $^{\mathrm{110}}$Cd sample and activating it with thermal neutrons, we produced the desired $^{\mathrm{111m}}$Cd isomer. With a very well calibrated High Purity Germanium detector, the gamma-rays as well as the X-rays corresponding to the 150 keV transition were observed, and their relative intensities measured. Our preliminary $\alpha_{\mathrm{K}}$ value results is 1.458 $\pm$ 15, which agrees with the theoretical $\alpha _{\mathrm{K}}$ value that includes the atomic vacancy, and disagrees with the no-vacancy calculation.   

Using Pulse Shape Discrimination to Increase the Range of Particle Identification in the FAUST Array

Heavy-ion collisions are an important probe of the nuclear Equation of State, however being able to isotopically identify light charged particles (LCP) along with a broad range of heavier intermediate mass fragments (IMF) in a compact detector presents its own set of challenges. The identification of LCPs and lighter IMFs can be achieved via a pulse shape discrimination (PSD) technique using the FAUST CsI(Tl) detectors. This technique can be combined with the more traditional $\Delta E-E$ technique to widen the range of isotopic particle identification of the heavier IMFs. The PSD technique involves nearly full waveform digitization and machine learning for a significant range of isotopic identification of LCPs and light IMFs. Simulated data from Geant4 will be presented along with results from recent online tests.   

Universal Parametrization of Thermal Photon Production in Hadronic Matter

As the production of photons and dileptons from high-energy collisions is able to provide information on the high temperature and high density phases of nuclear matter, an improved and universal parametrization of the rather involved microscopic calculations is key to honing the theory behind this production. We focus on photon emission rates from hadronic many-body calculations of the in-medium rho spectral function, which includes the effects of baryons and antibaryons. Across a range of temperatures from 0.1 to 0.18 GeV and baryon chemical potentials from 0 to 0.4 GeV, a parametrization of thermal photon rates for energies from 0.2 to 5 GeV is numerically determined through the use of nested fitting methods. This provides a fully functional description of thermal photon production largely within an unprecedented 20{\%} of the calculated values from the spectral function, a significant reduction in error from available parametrizations. The contribution of photons and dileptons from pion-pion bremsstrahlung is evaluated for the importance of its contribution. The functional form, coupled with the comparison to the bremsstrahlung production of thermal photons, will provide a baseline for guiding future studies.   

An Optical Model Potential for 3He Projectiles with Light Targets

In this study, we produce a optical model potential for 3He by parameterizing elastic scattering data with Lithium-6 and Carbon-12 targets at incident energies from 11MeV to 72MeV. Although previous global optical model potentials for A=3 nuclei with heavy targets have been produced, often these global potentials have difficulty reproducing experimental measurements of 3He elastic scattering from lighter nuclei, such as Lithium-6 and Carbon-12. Therefore, we focused our search on a systematic potential that can reproduce data from lighter target scattering. Using the optical model parameter search program MINOPT, we fit the elastic scattering data to produce global potential parameters. Experimental angular distributions of differential cross sections of the 3He elastic scattering from A$\sim$6 and A$\sim$12 target nuclei are compared to optical model calculations using the new parameters.   

Constrained Molecular Dynamics (CoMD) Model With Generalized Symmetry Energy

Constrained Molecular Dynamics is a computer program which models the dynamics and interactions of nucleons in nuclei. CoMD is a model in which the computational time is short enough to allow the study of the heaviest nuclei systems. Following the liquid drop model and including the Pauli Exclusion Principle, CoMD is used to study the Nuclear Equation of State (NEOS). Studying the NEOS through computer modeling can help predict and study exotic stable and unstable nuclei, light and heavy isotopes extending the chart of nuclides. Operation consists of producing ground state nuclei, and modeling collisions between these nuclei. It can also be used to predict whether or not a certain system consisting of any combination of nucleons can be stable. Since the model is currently fairly simple in principle, the goal is to modify the code adding a more robust equation for the symmetric potential energy, which in turn will produce more general data to study and analyze. The idea is that the symmetry potential takes a similar shape as the two body potential and the three body potential which is explained by Giuliani, Zheng and Bonasera, Progress in Particle and Nuclear Physics 76, 116 (2014). Once modified, it will be tested and compared to the original results.   

Effects of Photon Absorption in High Energy Heavy Ion Collisions

Photons are an important probe of the hot and dense nuclear matter created in high-energy collisions of nuclei at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). Since the mean free path of photons is larger than the size of the fireball of nuclear matter, final state interactions of photons are usually neglected. In light of recent tension between theoretical calculations and data from RHIC and LHC, we study the effect of reabsorption of photons on elliptic flow v2 and on the nuclear modification factor RAA. We consider photons emitted in primary hard collisions and thermal photons from quark-gluon plasma and hot hadron gas. We use the jet-quenching code PPM to simulate the propagation of those photons in a fireball of quark-gluon plasma and hot hadron gas created by collisions of heavy nuclei. For the absorption cross-sections we consider three different approaches: (a)Compton and pair production processes calculated by us in a static approximation, (b)the photon damping rates calculated by Thoma (1995), and (c)absorption rates derived from a recent photon calculation by van Hees et al.   

Energy Transfer Based Nanocomposite Scintillator for Radiation Detection

Scintillators are the materials that emit light upon irradiation with high energy radiation like X-ray or gamma-ray. Inorganic single crystal and organic (plastic and liquid) are the two most used scintillator types. Both of these scintillator kinds have advantages and disadvantages. Inorganic single crystals are expensive and difficult to grow in desire shape and size. Also, single crystal scintillator such as NaI and CsI are very hygroscopic. On the other hand, organic scintillators have low density which limits their applications in gamma spectroscopy. Due to high quantum yield and size dependent emission, nanoparticles have attracted interested in various field of research. Here, we have studies the nanoparticles for radiation detection. We have synthesized nanoparticles of Cerium fluoride (CeF3), Zinc Oxide (ZnO), Cadmium Telluride (CdTe), Copper complex and Zinc sulfide (ZnS). We have used Fluorescence Resonance Energy Transfer (FRET) principle to enhance the luminescence properties of nanocomposite scintillator. Nanocomposites scintillators are structurally characterized with X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). Optical properties are studied using Photoluminescence, UV-Visible and X-ray. Enhancements in the luminescence are observed under UV and X-ray excitation. Preliminary studies shows nanocomposite scintillators are promising for radiation detection.   

$^{94}$Mo($\gamma $,n) and $^{90}$Zr($\gamma $,n) cross-section measurements towards understanding the origin of $p$-nuclei

The nucleosynthesis beyond iron of the rarest stable isotopes in the cosmos, the so-called $p$-nuclei, is one of the forefront topics in nuclear astrophysics. Recently, a stellar source was found that, for the first time, was able to produce both light and heavy $p$-nuclei almost at the same level as $^{56}$Fe, including the most debated $^{92,94}$Mo and $^{96,98}$Ru; it was also found that there is an important contribution from the $p$-process nucleosynthesis to the neutron magic nucleus $^{90}$Zr [1]. We focus here on constraining the origin of $p$-nuclei through nuclear physics by studying two key astrophysical photoneutron reaction cross sections for $^{94}$Mo($\gamma $,n) and $^{90}$Zr($\gamma $,n). Their energy dependencies were measured using quasi-monochromatic photon beams from Duke University's High Intensity Gamma-ray Source facility at the respective neutron threshold energies up to 18 MeV. Preliminary results of these experimental cross sections will be presented along with their comparison to predictions by a statistical model based on the Hauser-Feshbach formalism implemented in codes like TALYS and SMARAGD. \\[4pt] [1] C. Travaglio, \textit{et. al.}, ApJ 739 (2011) 93.   

Construction of a 1 MeV Electron Accelerator for High Precision Beta Decay Studies

Beta decay energy calibration for detectors is typically established using conversion sources. However, the calibration points from conversion sources are not evenly distributed over the beta energy spectrum and the foil backing of the conversion sources produces perturbations in the calibration spectrum. To improve this, an external, tunable electron beam coupled by a magnetic field can be used to calibrate the detector. The 1 MeV electron accelerator in development at Triangle Universities Nuclear Laboratory (TUNL) utilizes a pelletron charging system. The electron gun shoots 10$^4$ electrons per second with an energy range of 50 keV to 1 MeV and is pulsed at a 10 kHz rate with a few ns width. The magnetic field in the spectrometer is 1 T and guiding fields of 0.01 to 0.05 T for the electron gun are used to produce a range of pitch angles. This accelerator can be used to calibrate detectors evenly over its energy range and determine the detector response over a range of pitch angles.   

Measurement of the $^{86}$Kr (n, $\gamma ) \quad^{87}$Kr Cross Section Between 0.43 MeV and 14.8MeV

The purpose of this research was to determine the cross section of the $^{86}$Kr (n, $\gamma ) \quad^{87}$Kr reaction for incident neutron energy levels between 0.43 MeV and 14.8 MeV using the neutron activation technique. The half-life of this reaction is 76.3 minutes and the flux of incident neutrons will be measured using $^{115}$In foils (except for 14.8MeV where $^{197}$Au foils will be used) that are 0.125 millimeters thick and 2.0 centimeters in diameter. This information is applicable to astrophysics, specifically the slow neutron capture process that occurs in low neutron density environments and creates heavier nuclei. This information is also relevant for the National Ignition Facility and the Lawrence Livermore National Laboratory with regards to their Deuterium-Tritium Internal Confinement Fusion plasma.   

A Discrepancy between Two Criteria of Stability for Hybrid Stars

Neutron stars, along with other compact matter, are some of the most stable structures in the universe. Their stability can be disrupted, however, by radial oscillations, which may cause them to collapse into black holes. John Bardeen, in his Catalogue of Methods, detailed two methods by which we can determine the stability of compact stars for a given equation of state: direct calculation of the oscillation frequency with Chandrasekhar's equation or a qualitative examination of a mass-radius plot. These two methods were believed to agree until Glendenning et al. proposed the existence of a white dwarf with a strange quark core. We observed that Glendenning's white dwarf showed disagreement between Bardeen's methods. With this motivation, we examined the stability of a similar family of hybrid stars which contain a quark matter core surrounded by a nuclear matter envelope. The equations of state for such stars exhibit either a kink or discontinuity. By reproducing the calculations of these methods, we observed that Bardeen's methods do not agree for these stars as well. We believe that this discrepancy stems from the fact that Chandrasekhar's equation is incompatible with discontinuous equations of state and are working to resolve this incompatibility.   

Soundtracks to Accompany Visualizations of Nuclear Pasta Simulations

Nuclear pasta is a substance found in neutron stars and core-collapse supernovae, arising at the extreme densities near nuclear saturation, when the attractive nuclear and repulsive coulomb forces mold the dense sea of protons and neutrons into shapes such as spheres, tubes, and slabs, which somewhat resemble different types of pasta. The structures are analyzed using molecular dynamical simulations for different proton fractions, temperatures, densities, and number of nucleons. The system is stressed by stretching it, squeezing it, or subjecting it to some outside force. In order to obtain a more complete representation of how the nuclear pasta responds, sound tracks were produced to accompany videos of stretching simulations. The audio tracks were made by assuming sound waves are produced from changes in the nucleon density. This density was calculated within a small region at frequent time intervals during the run. The resulting sound track was then synced with a video of the run in order to emphasize the development of the system as the pasta moves and breaks.   

Molecular Dynamics of Nuclear Pasta in Neutron Stars

During a core collapse supernova, a massive star undergoes rapid contraction followed by a massive explosion on the order of a hundred trillion trillion nuclear bombs in less than a second. While most matter is expelled at high speeds, what remains can form a neutron star. The bulk of a neutron star does not contain separate nuclei but is itself a single nucleus of radius $\sim$10 km. In the crust of a neutron star, density is low enough that some matter exists as distinct nuclei arranged into crystalline lattice dominated by electromagnetic forces. Between the crust and core lies an interesting interface where matter is neither a single nucleus nor separate nuclei. It exists in a frustrated phase; competition between electromagnetic and strong nuclear forces causes exotic shapes to emerge, referred to as nuclear pasta. We use Molecular Dynamics (MD) to simulate nuclear pasta, with densities between nuclear saturation density and approximately one-tenth saturation density. Using MD particle trajectories, we compute the static structure factor S(q) and dynamical response function to describe both electron-pasta and neutrino-pasta scattering. We relate the structure and properties of nuclear pasta phases to features in S(q). Finally, one can integrate over S(q) to determine transport properties such as the electrical and thermal conductivity. This may help provide a better understanding of X-ray observations of neutron stars.   

r-Process Sensitivity Studies of Beta-Delayed Neutron Emissions

The r-process is a nucleosynthesis mechanism responsible for the formation of elements heavier than iron. It is unclear where in the galaxy the r-process occurs, but the two most likely locations are supernovae and neutron star mergers. This process is complex, and different initial conditions have a large affect on the resulting abundances of the elements produced. Using an r-process nuclear network code, we examined influence of beta-delayed neutron emissions (BDNE) probabilities. We tested single isotopes of every element with BDNE either maximized or turned off, while all other nuclei were held at their normal theoretical BDNE probability. The results were compared with a baseline, and we looked for local and global changes to the final abundance patterns. BDNE probabilities for nuclei 5-15 neutrons from stability were found to have the most substantial effects. Results with BDNE maximized had the most drastic changes from baselines.   

Late Time Decays and the r-Process Abundance Pattern

The r-process is the rapid capture of neutrons creating unstable neutron rich nuclei. This process is very quick, lasting only a couple of seconds. Afterwards those nuclei decay to stability over much longer timescales. We wrote a computer program to model the ways that nuclei created by the r-process decay back to stability using theoretical and experimental values for the probabilities that a given nuclei would beta decay, beta delayed neutron emit, alpha decay, and beta delayed fission. We then compared the resulting elemental abundances to abundance patterns from metal poor halo stars. We also examined the ratios of thorium 232 to uranium 238 and uranium 235 to uranium 238. We found the thorium to uranium ratio to be particularly sensitive to how late-time fission is included.   

PIXE Analysis of Atmospheric Aerosol Samples in an Urban Area in Upstate NY

Extremely fine particles (PM2.5) are found to penetrate deep into the lungs and hence, are found to have harmful health effects on humans. Atmospheric aerosol samples collected in Schenectady, NY were analyzed for evidence for air pollution; specifically lead pollution over the past 12 months. Air samples were collected on 7$\mu $m Kapton foils using a nine-stage cascade impactor that separates the particulate matter by aerodynamic size. A 2.2MeV proton beam impacts the target samples. X-ray intensity versus energy spectra was produced using an Amptek silicon drift detector. Proton-induced x-ray emission (PIXE) techniques were used to analyze the energy spectra and we determined a range of 16 elements present in the aerosol samples including, Al, Si, P, S, Cl, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Br, and Pb. The elemental composition and concentrations of these elements were determined using GUPIX. Many of the elements suggest airborne soils, however we see trace amounts of lead concentrations only at the minimal level of detection around 1 ng/m3. Preliminary results suggest that lead pollution is not significant however; we believe that the trace amounts of lead detected are due to fuel emissions from small aircraft due to the sampling site near an airport.   

PIXE Analysis of Aerosol and Soil Samples Collected in the Adirondack Mountains

We have performed an elemental analysis of aerosol and soil samples collected at Piseco Lake in Upstate New York using proton induced X-ray emission spectroscopy (PIXE). This work is part of a systematic study of airborne pollution in the Adirondack Mountains. Of particular interest is the sulfur content that can contribute to acid rain, a well-documented problem in the Adirondacks. We used a nine-stage cascade impactor to collect the aerosol samples near Piseco Lake and distribute the particulate matter onto Kapton foils by particle size. The soil samples were also collected at Piseco Lake and pressed into cylindrical pellets for experimentation. PIXE analysis of the aerosol and soil samples were performed with 2.2-MeV proton beams from the 1.1-MV Pelletron accelerator in the Union College Ion-Beam Analysis Laboratory. There are higher concentrations of sulfur at smaller particle sizes (0.25-1$\mu $m), suggesting that it could be suspended in the air for days and originate from sources very far away. Other elements with significant concentrations peak at larger particle sizes (1-4$\mu $m) and are found in the soil samples, suggesting that these elements could originate in the soil. The PIXE analysis will be described and the resulting data will be presented.   

Proton-Induced X-Ray Emission Analysis of Crematorium Emissions

There has been considerable debate in recent years about possible mercury emissions from crematoria due to amalgam tooth restorations. We have performed a proton-induced X-ray emission (PIXE) analysis of aerosol and soil samples taken near the Vale Cemetery Crematorium in Schenectady, NY, to address this concern. The aerosol samples were collected on the roof of the crematorium using a nine-stage, cascade impactor that separates the particulate matter by aerodynamic diameter and deposits it onto thin Kapton foils. The soil samples were collected at several different distances from the crematorium and compressed into pellets with a hydraulic press. The Kapton foils containing the aerosol samples and the soil pellets were bombarded with 2.2-MeV protons from the 1.1-MV tandem Pelletron accelerator in the Union College Ion-Beam Analysis Laboratory. We measured significant concentrations of sulfur, phosphorus, potassium, calcium, and iron, but essentially no mercury in the aerosol samples. The lower limit of detection for airborne mercury in this experiment was approximately 0.2 ng/m3. The PIXE analysis of the soil samples showed the presence of elements commonly found in soil (Si, K, Ca, Ti, Mn, Fe), but no trace of mercury.   

New Levels of $^{157}$Pm

Gamma rays in coincidence with isotopically-identified fission fragments using VAMOS++ and EXOGAM, produced using $^{238}$U on a $^{9}$Be target, at an energy around the Coulomb barrier have been reported. In the present work, we have combined data from the in-beam mass- and Z-gated spectra with the $\gamma$-$\gamma$-$\gamma$-$\gamma$ data from $^{252}$Cf (SF) to assign transitions and levels in $^{157}$Pm. In contrast to Hwang, 2009, the transitions previously assigned to $^{156}$Pm are all seen in the M-Z gated spectra of $^{157}$Pm and are not seen in the M-Z gated spectra of $^{156}$Pm. The new expanded levels of $^{157}$Pm are remarkably similar to those of the levels in $^{155}$Pm, which have been assigned as a rotational band built on $\pi$ 5/2 [532].   

Uniformity and Crosstalk in Multi-Anode Photomultiplier Tubes

Multi-anode photomultiplier tubes can process signals from 64 different sources, by splitting the anode into 64 different segments, and analyzing the signal from each of those segments separately. With a precise understanding of how they function, they can therefore be used as a substitute for 64 separate single photomultiplier tubes (PMTs). This could increase the convenience and reduce the cost of many larger experiments, which require large scintillating arrays, and therefore many PMTs in order to obtain better precision. However we need to have both a measure of how much variance in signal gain there is between different anodes, and how much cross-talk there is between adjacent channels. In order to measure the uniformity we compared signal strength from a fiber optic of uniform intensity, when placed at the center of each anode. In order to measure crosstalk we looked at the signal strength in the adjacent anodes when the LED was at the center of an anode. Our uniformity measurements showed that all the anodes were within the factory allowance, and showed that uniformity is consistent across several voltages below 1000V. Our measure of the signal strength of the crosstalk will allow later experiments to take it's effect into account.   

Studies of $^{3}$He polarization losses during NMR and EPR measurment and Polarized $^{3}$He target cell lifetime

The $^{3}$He target cell polarized by spin-exchange optical pumping(SEOP) is used as a neutron substitute to study the inner structure of the neutron. In our lab, nuclear-magnetic-resonance(NMR) is used to measure the relative polarization and electron-paramagnetic-resonance(EPR) is used to measure the spin exchange EPR frequency shift parameter of potassium and rubidium in our target cell presented in magnetic fields. The alkali in the cell is used to facilitate the polarization of $^{3}$He. The first part of my work presents the study of the polarization losses of the cell during both NMR and EPR. With the help of improved RF coils, we keep the background noise received by pickup coils reasonably low, but three other kinds of losses are inevitable: losses during Adiabatic Fast Passage (AFP) sweep, losses due to flux change caused by different cell orientation with respect to RF fields and physical losses. Fortunately there is only flux change in NMR measurements. The second part of my work presents the study of cell lifetime improvement. The polarization decreases in a process called relaxation exponentially. The lifetime of a cell is how long it can keep its polarization. The typical lifetime of cells produced in our lab is about 22 hours. With a newly designed vacuum system   

Effective Mass of a Single $\pi^0$ Interacting With Itself

The effective mass of a single $\pi^0$ $\pi$on when interacting with itself has been calculated. The calculation was done using C++ and It++, a C++ library extension which attempts to emulate MATLAB. This calculation was done by generating a matrix $G$ from a database, and two meson state matrices $M_0$, and $M_1$. $G$, $M_0$, and $M_1$ are each $1584 \times 1584$, however, careful algebra, knowing the properties of these matrices, enables only the top left $792 \times 792$ block of each to be created, saving computation time and reducing numerical error. The $\pi^0$ self-interacting-effective-mass has been calculated to be 0.0755(190).   

Design of Drift Chamber 5 for the COMPASS II polarized Drell-Yan experiment

The COMPASS project is a fixed-target nuclear physics experiment at CERN which explores the internal structure of the proton, and~COMPASS ll's polarized Drell-Yan experiments will be exploring the quark angular momentum contribution to the spin of the proton through Semi-Inclusive Deep Inelastic Scattering. As a part of this process, Drift Chamber 5 (DC5), based on DC4 built by CEA-Saclay, must be constructed to replace a faulty straw chamber. The 23 total frames of DC5 have an outside measurement of 2.94m by 2.54m, with the 8 anode frames having a total of 4616 \textgreater 2m-long wires, giving a detection region of 4.19m\textasciicircum 2 with a resolution of 200 microns. These wire planes are orientated with the x- and x'-frames in the vertical x-direction, the y- {\&} y'-frames in the horizontal y-direction, the u- {\&} u'- frames offset $+$10deg from the vertical x-direction, and the v- {\&}v'-frames offset -10deg from the vertical x-direction, and are strung with {\O}100 micron field wires and {\O}20 micron sense wires. In order to solve left-right ambiguity, x', y', u', and v' are shifted by 4mm, or one drift cell. The x- and y-frames have 513 wires strung across them, with the field wires at 400g of tension, the sense wires at 55g on the x-frames, and 70g on the y-frames. The u- and v-frames will have 641 wires, with the field wires at 400g, and the sense wires at 55g. DC5 will also have an updated front end electronics setup, using a new pre-amplifier-discriminator chip, in order to allow the recording of more events per second.   

Wiring the new COMPASS Drift Chamber

COMPASS, a fixed-target experiment at CERN, will examine the first ever polarized Drell-Yan events that may illuminate how the quark angular momentum contributes to the spin of the proton. A new drift chamber must be constructed to replace an older straw chamber that is currently in use. In order to construct the drift chamber 4616 gold-plated tungsten wires are used, half are 100 micron (field wires) which provide an electrical field and half are 20 micron (sense wires) which measure position. Because of the difference in wire width, two very different stringing techniques had to be developed. The 20 micron sense wire was too fragile and thin to be handled in the same manner as the 100 micron field wire, so different tools had to be used in order to ensure the stability and efficacy of the chamber. Additionally, different soldering techniques had to be used for the two different types of wires to guarantee both that the field wires did not slip out of their solder joints during the process of stringing the sense wires and that both types of wires had smooth, even solder joints that would not require repair. This poster will detail several aspects of wire stringing, including how to string different widths of wire and how to overcome difficulties arising from using two different types of wire during the stringing process.   

Ensuring Wire Alignment for the New COMPASS Drift Chamber

COMPASS is a fixed-target experiment at CERN investigating the internal structure of the proton. Polarized Drell-Yan measurements at COMPASS will explore how the quark orbital angular momentum contributes to the spin of the proton. To enable this measurement, several straw tube chambers need to be replaced due to long term wear. One of the replacement chambers, drift chamber DC5, is being built at Old Dominion University based on a prototype from UIUC and existing COMPASS drift chambers. DC5 consists of 4 wire planes with 513 wires (256 [20 $\mu$m] sense wires and 257 [100 $\mu$m] field wires alternating) and 4 wire planes at a 10 degree offset with 641 wires each. Each of these 4616 wires need to be aligned within either 100 $\mu$m(sense wire) or 200 $\mu$m (field wire) of the center of the solder pad to ensure the accuracy of the drift chamber. Problems that arose during stringing include initial alignment of the wire and efficient soldering techniques. Also, because the field wires charged at -1750 volts will be 4 mm from the sense wires, there should be no gaps or points in the solder to prevent arcing. This poster will discuss the alignment techniques, soldering methods, testing, and repair process for the wires.   

Analysis of $Z^{0}+$jet production with Simulations and Fastjet

We present an analysis of $Z^{0}+$jet production in simulations of hadron collisions. In high-energy p-p collisions, the quarks and gluons are the particles that initiate the reaction. A $Z^{0}+$jet event is one in which a $Z^{0}$ boson and a quark are created. Since the two initial protons collide in the CM frame the $Z^{0}$ and the quark should be in opposing directions, due to conservation of momentum. In the simulation we follow the leading quark until it bursts into a jet; the quark bursts into a jet because quarks cannot exist in free space. We can use this to find the jet in the simulations. We concurrently use the anti-kt Fastjet algorithm to cluster the final state hadrons that came from the fast quark so we can estimate the kinematics of the quark. In future analysis of heavy ion collisions, the same analysis can be applied and a loss of energy may be identified. This analysis may be applied to data, when there is more statistics.   

Inspection of anode and field wires for the COMPASS drift chamber, DC5, with Environmental Scanning Electron Microscope

The COMPASS experiment at CERN uses a secondary pion beam from the Super Proton Synchrotron (SPS) at CERN to explore the spin structure of nucleons. A new drift chamber, DC5, will be integrated into the COMPASS spectrometer to replace an aging straw tube detector. DC5 will detect muon pairs from Drell-Yan scattering of a pion-beam off a transversely polarized proton target. This data will be used to determine the correlation between transverse proton spin and the intrinsic transverse momentum of up-quarks inside the proton, the Sivers effect. DC5 is a large area planar drift chamber with 8 layers of anode-frames made of G10 fiberglass-epoxy. The G10 frames support printed circuit boards for soldering 20$\mu$m diameter anode and 100$\mu$m diameter field wires. The anode planes are sandwiched by 13 graphite coated Mylar cathode planes. To ensure a well-functioning of DC5, the wires were carefully tested. An optical inspection and a spectral analysis was performed with an Environmental Scanning Electron Microscope (ESEM) to verify the composition and dimensions and the integrity of the gold plating on the surface of these wires. The spectra of the wires were studied at 10 and 30 keV.   

Construction and Gluing of G10 Frames and Printed Circuit Boards to be used in COMPASS Drift Chamber 5

COMPASS is a fixed-target nuclear physics experiment at CERN which explores the internal structure of the proton. One specific area of research is the measurement of single transverse spin asymmetries in pion beam induced Drell-Yan production of muon pairs from polarized proton targets. The spin dependence of the Drell-Yan cross section may be indicative of contributions from quark orbital angular momentum to the spin of the proton. The University of Illinois at Urbana-Champaign (UIUC), in collaboration with institutes in Taiwan, France, Italy and Germany, is designing and building a new drift chamber, DC5, to replace an aging detector in the COMPASS spectrometer. The frames supporting the anode wires and cathode planes in DC5 are constructed from G10, a fiberglass-epoxy composite. Once the individual sides of each frame have been milled, they are glued together at the corner lap joints. Additionally, printed circuit boards are glued to the anode frames, where sense and field wires will later be soldered. To maintain optimal operation of the drift chamber, the frame thickness after gluing must be within 50 $\mu $m of the design value. This presentation will explain the methods employed to achieve the required tolerances for this precision gluing process.   

Wire Tension Measurements and Analysis for the New COMPASS Drift Chamber

In 2010, the COMPASS experiment, located at the CERN Super Proton Synchrotron, approved the further investigation of the nucleon spin structure. The incorporation of the new drift chamber DC5 into the COMPASS spectrometer will facilitate the measurements of the spin-dependent Drell-Yan process using a 190 GeV $\pi^-$ beam on a transversely polarized proton target. Upon assembling the anode planes of DC5 at Old Dominion University (Norfolk, VA), gravitational and electrostatic sag simulations performed by Garfield indicated that 20 $\mu$m diameter sense wires should have a tension of 0.67 N and 100 $\mu$m diameter field wires a tension of 3.92 N. When a voltage of 1750 V is applied to the field wires, they will be displaced by 135 $\mu$m and the sense wires by 85 $\mu$m. To avoid further wire displacements that could cause ambiguity in the detected paths, each wire has to be strung at these ideal tensions. Data have been collected from more than 3600 wire tension tests. The analysis of these data yielded an improved understanding on the wire tension tendencies. 15\% of the wires had to be re-strung given that tension was lost due to friction between the wire and the alignment board. The tension measurement methods, analysis, and results will be presented.   

Tension Tests of Tungsten Based Sense Wires and Copper Based Field Wires for the COMPASS Drift Chamber 5

COMPASS is a nuclear physics experiment at CERN which explores the spin structure of the nucleon. A new drift chamber, DC5, is being constructed for the COMPASS spectrometer at the University of Illinois. DC5 will detect charged muon pairs from negative pions scattering off a transversely polarized proton target in order to study the spin-dependence of the Drell-Yan process for the first time. The spin dependence of the Drell-Yan process may signal contributions from quark orbital angular momentum to the spin of the proton. In DC5, particle detection is performed using 20 $\mu$m diameter gold plated tungsten sense wires and 100 $\mu$m diameter gold plated copper field wires. The wires are strung under tension across the length of the chamber. Mechanical stability under the influence of electric forces requires high wire tensions. In order to determine how much the wires can be stretched, a series of tension tests was performed to identify their regions of elasticity and their breaking points. The results from these tests were used to determine the tension used in stringing the wires and soldering them onto the printed circuit boards supporting the sense and field wires in DC5.   

GARFIELD Computer Program Simulation of the COMPASS Drift Chamber 5

COMPASS is a nuclear physics experiment at the Super Proton Synchrotron (SPS) at CERN. The purpose of COMPASS is the study of hadron structure and hadron spectroscopy with high intensity muon and hadron beams. To further study the Drell-Yan process in scattering pion beams off polarized proton targets, COMPASS requires sophisticated tracking devices to determine the trajectory of scattered charged muon pairs. The University of Illinois at Urbana-Champaign is currently constructing the Drift Chamber 5 (DC5) to replace old straw-tube tracking detectors in the COMPASS spectrometer. DC5 is composed of 8 layers of anode and 13 layers of cathode frames made out of G10, a fiberglass-epoxy composite. The high rates for the Drell-Yan measurement require a small drift cell and precise mechanical tolerances have to meet in order to achieve good position resolution. GARFIELD simulations were carried out to study the impact of mechanical tolerances on the drift chamber performance in particular the position resolution that can be reached. The details of the DC5 GARFIELD simulation and results for signal development and position resolution will be presented.   

Progress of the Study of Neutron Interactions with $^{7}$Be

Big Bang Nucleosynthesis (BBN) is today a parameter-free theory. It correctly predicts the abundance relative to hydrogen, of primordial deuterium, helium, and helion but over predicts the relative abundance of primordial $^{7}$Li which is primarily (95{\%}) the byproduct of the decay of $^{7}$Be. This has been dubbed as the primordial $^{7}$Li problem. We are proposing to study the interaction of neutrons with $^{7}$Be in order to understand the direct destruction of the primordial $^{7}$Be. The experiment being proposed will be performed at the SARAF facility in Israel using the LiLiT neutron generator and an implanted $^{7}$Be target produced at ISOLDE from a $^{7}$Be sample produced at the PSI. An implantation set up was constructed and tested at ISOLDE using 35 keV $^{10}$B. The implanted $^{10}$B targets were tested using the intense CERN Pu-Be source. For the first generation measurement of the $^{7}$Be(n,$\alpha$) reaction we plan to use CR-39 plastic track detectors to detect the emanating alpha-particles (and protons). Such detectors were tested in our lab using alpha-source and we are developing the use of these detectors for our measurement. Future experiments will utilize a split gas ionization chamber and silicon detectors. We will review the progress of this research project.   

The monitoring of environmental conditions for SeaQuest

The SeaQuest/E906 experiment uses the 120 GeV Main Injector at Fermi National Accelerator Lab (FNAL) is to measure the quark and antiquark structure of the nucleon using Drell-Yan scattering. The spectrometer acceptance emphasizes valence quarks in the beam protons annihilating with anti-quarks in the hydrogen, deuterium and heavy nuclear targets. The SeaQuest spectrometer was built in the New Muon 4 (NM4) Hall, which can have 5-7 degrees C temperature gradients and humidity gradients between the bottom and top of the detectors.These gradients can affect detector performance. Thus conditions in the NM4 area such as pressure, humidity and temperature need to be monitored since they can impact detector performance and high voltage leakage currents. The system developed to record these data has the capability to be checked independently of the rest of the slow control system, allowing for studies independent of the main data acquisition system. The setup, programming, and expandability of this system will be presented.   

Measuring the number of protons per pulse using an in beam Cherenkov counter for the trigger inhibit at SeaQuest

FNAL E906, also known as SeaQuest, is a fixed target Drell-Yan experiment using the Fermilab 120 GeV Main Injector. It is designed to determine the ratio of anti-down to anti-up quarks within the nucleon. In order to more effectively take data it was necessary to inhibit the trigger when pulses have too many protons. This was achieved using a Cherenkov counter to identify the number of protons in each 1 nanosecond beam pulse during each spill. This information was also graphed for display in real time to monitor of the performance of the trigger inhibit. The display shows the frequency of protons per pulse around the trigger inhibit, which is adjusted to block spills before and after large pulses. This allows visual information of the beam intensity near the inhibit to see if the large pulses also have larger numbers of protons. The display also shows the time before and after these large pulses occur since the effects will extend past the time of a large pulse due to the slower response of drift chambers that will have had a large number of particles traversing them.   

SeaQuest / E906 Shift Alarm System

SeaQuest, Fermilab E906, is a fixed target experiment that measures the Drell-Yan cross-section ratio of proton-proton to proton-deuterium collisions in order to extract the sea anti-quark structure of the proton. SeaQuest will extend the measurements made by E866/NuSea with greater precision at higher Bjorken-x. The continuously running experiment is always being monitored. Those on shift must keep track of all of the detector readouts in order to make sure the experiment is running correctly. As an experiment that is still in its early stages of running, an alarm system for people on shift is being created to provide warnings, such as a plot showing a detector's performance is sufficiently different to need attention. This plan involves python scripts that track live data. When the data shows a problem within the experiment, a corresponding alarm ID is sent to the MySQL database which then sets off an alarm. These alarms, which will alert the person on shift through both an audible and visual response, are important for ensuring that issues do not go unnoticed, and to help make sure the experiment is recording good data.   

Optimization of Target-Dump Separation at Fermilab Seaquest Experiment

SeaQuest (E906) is a fixed-target Drell-Yan experiment at Fermilab designed to measure the flavor asymmetry of the light sea quarks of the nucleon. Collisions of the 120 GeV proton beam from Fermilab's Main Injector with hydrogen, deuterium, and nuclear targets result in the production of muon pairs; however, muon pairs are also produced in the iron beam dump. Spatial cuts on reconstructed tracks must be used to separate background events originating in the dump from signal events produced by the target. The analysis to optimize the efficiency and purity of target events, based on both simulated and real data, will be presented.   

Leak Rate Test for a Fiber Beam Monitor Contained in a Vacuum for the Muon g-2 Experiment

The muon g-2 experiment at Fermilab aims to measure the muon anomalous magnetic moment with a precision of 0.14 parts per million (ppm). The measurement will build on the Brookhaven-based E821 experiment, which yielded results suggesting new physics such as supersymmetry. The Fiber Beam Monitors (FBMs) are used in the experiment to determine the position and observe the motion of a muon beam and monitor the properties of the beam over time. The FBMs support a 9 cm $\times$ 8 cm ``harp'' with 7 scintillating fibers separated from each other by 13 mm, each with a diameter of 0.5 mm. The experiment requires a vacuum of less than $1\times10^{-6}$ Torr to prevent trapping of electrons ionized from the residual gas by the electrostatic quadrupoles. To meet this requirement the FBMs must have a leak rate of less than $5 \times 10^{-5}$ Torr L/s. We have constructed a vacuum system to simulate these conditions and have determined the leak rate of the FBMs within the constructed vacuum apparatus. This leak rate will be reported, along with preliminary results from tests of the light output from the scintillating fibers.   

The Optical Characterization of Aerogel Tiles for Cherenkov Detectors at Jefferson Lab

The purpose of this project is to determine the scattering and absorption lengths of aerogel tiles of refractive indices ranging from 1.03 to 1.01 produced by Matsushita Electric Works and Japanese Fine Ceramics Center which are used in the Cherenkov detectors at Jefferson Lab. Cerenkov detectors use Cherenkov radiation to detect and identify particles traveling though them. Since light traveling through aerogel is integral to their use as Cherenkov counters, knowledge of aerogel's optical properties is essential. The optical properties measured were the likelihood of a photon being absorbed or scattered as it passed through aerogel. Both properties were tested by shining a collimated beam of light 470nm LED light through different thicknesses of aerogel: up to 20 tiles each about 1 cm thick. The change in intensity was measured with a 5-inch photomultiplier tube. Scattering has a great effect over large distances and absorption has a very small effect over shorter distances. Scattering was measured first, at aerogel thicknesses of 1-5 cm, absorption measured at distances of 10-20 cm, taking into account the previously calculated scattering. This presentation will consist of the results on the scattering and absorption length of aerogel for use in Jlab's Cherenkov detectors.   

Characterization of Large Diameter PMTs for Kaon Cerenkov Detector

The 12GeV upgrade at the Jefferson Laboratory allows for unique new opportunities to study hadron structure through kaon production in Hall C, a threshold aerogel detector was constructed at the Catholic University of America. It uses the emission of Cerenkov radiation at different indices of refraction ranging from 1.03 to 1.01 to distinguish pions, kaons, and protons. An important aspect of this detector is the collection of very small amounts of light, in particular as the aerogel refractive index decreases. The Hall C aerogel detector uses the Photonis XP4500 large-diameter photomultiplier tubes (PMT) in order to detect these small traces of light. The purpose of this project is to explore the performance of alternative large-diameter PMTs and compares them to that of the XP4500. The PMT uniformity across the photocathode was characterized through scans along the surface of the PMT with a low-intensity, focused LED, thereby creating a 3D image of the gain at each section. The method of scanning consists of a two axis step motor moving an LED light source on a 100 x 100 grid parallel to the face of the PMT, with 30 pulses of light from the LED at each step. The step motor scans with a resolution of 1.2 mm. Scans conducted in this manner result in high resolution images which pick up most sensitive/non-sensitive spots on the photocathode. In this presentation I will present the results of the characterization and performance test of the XP4500 and comparison to alternative large-diameter PMT models.   

Evaluation of LED-based Instrumentation for JLab Detectors

Light-Emitting Diodes have a multitude of uses due to their increasing efficiency, reliability, durability, and practical size. The wavelength-intensity properties of LEDs are important in the characterization of aerogel optical properties and thus the uniformity and performance of the Hall C threshold aerogel Cherenkov detectors at Jefferson Laboratory. LEDs are also practical for the PWO-based calorimeters at JLab for monitoring and recovering these crystals during and after exposure to radiation. This project is aimed at the construction and evaluation of LED-based instrumentation to characterize the optical properties of aerogel used in the JLab aerogel detectors and its application to future detectors. LEDs emit light at a nominal wavelength, but their spectrum covers a broad range. It is thus important to understand the LED spectrum. A spectrometer was constructed including a collimator, diffraction grating, and high-speed photodiode to measure the voltage, which was then converted into luminous intensity. This presentation will convey the results from measurements with LED-based instrumentation and discuss the application of LEDs covering wavelengths from the ultraviolet to near-infrared regions in future PWO-based detectors.   

Evaluation of LED-based Instrumentation for JLab Detectors

Light-Emitting Diodes have a multitude of uses due to their increasing efficiency, reliability, durability, and practical size. The wavelength-intensity properties of LEDs are important in the characterization of aerogel optical properties and thus the uniformity and performance of the Hall C threshold aerogel Cherenkov detectors at Jefferson Laboratory. LEDs are also practical for the PWO-based calorimeters at JLab for monitoring and recovering these crystals during and after exposure to radiation. This project is aimed at the construction and evaluation of LED-based instrumentation to characterize the optical properties of aerogel used in the JLab aerogel detectors and its application to future detectors. LEDs emit light at a nominal wavelength, but their spectrum covers a broad range. It is thus important to understand the LED spectrum. A spectrometer was constructed including a collimator, diffraction grating, and high-speed photodiode to measure the voltage, which was then converted into luminous intensity. This presentation will convey the results from measurements with LED-based instrumentation and discuss the application of LEDs covering wavelengths from the ultraviolet to near-infrared regions in future PWO-based detectors.   

Projected Vertical Drift Chamber Geometry Adjustments of the Qweak Experiment

The goal of the Qweak experiment, a parity-violating electron scattering experiment at Jefferson Laboratory, is to measure the weak charge of the proton to a high precision, within 4\% of its value. In order to make this precise measurement, the asymmetry of the scattering of right and left-handed electrons, and the momentum transfer of these electrons, must be known to a high enough precision to meet the budgeted uncertainty. The momentum transfer is ultimately determined through Monte Carlo simulations in GEANT4, which must agree with the data received from the experiment. However, we observed a slight discrepancy between simulation and experimental data caused by the track reconstruction program. The energies of the scattered electrons calculated from the experimental data had an octant dependence, which, along with some other evidence, signified a possible tilt in the drift chambers used to determine the location and direction of the scattered electrons. The tracking code was modified to account for any tilt of the detectors. After the code was modified, the octant dependence was mitigated and the scattered energies from the simulation and from the experimental data appear to be in better agreement.   

Track Reconstruction for Aluminum Scattering in the Qweak Experiment

The Qweak experiment, conducted at Jefferson Lab in Newport News, VA, made the first determination of the proton's weak charge by investigating the scattering of an electron beam off of protons in a hydrogen target. The casing of the target was made out of aluminum, and as a result some of the electrons do scatter off of the target's aluminum walls. The walls have thin upstream and downstream ``windows'' to minimize electron-aluminum interaction, where the former is the location where the beam enters the target while the latter is the location at which the beam exits. As we are only concerned with the electron-proton scattering, it is necessary to investigate the electrons that scattered off aluminum in more detail to understand how this background noise affects the measurement on hydrogen. Using Monte Carlo simulations of the experiment and reconstruction of the tracks that the electrons take, discrepancies between simulations, track reconstruction, and experimentally collected data were found.   

Analyzing the Performance of Multi-Anode PMTs for the SoLID Project at Jefferson Lab

As a part of their particle accelerator upgrade from 6 GeV to 12 GeV, Jefferson Lab is building a Solenoidal Large Intensity Device (SoLID). SoLID is a high rate and large acceptance particle detector containing multiple detectors including an electromagnetic calorimeter, and a large solenoidal magnet. Due to the large number of particles that need to be detected, SoLID needs a photomultiplier setup with high channel density. This research is to characterize the level of performance of Hamamatsu H10966 multi-anode Photomultiplier Tubes (PMTs) for the SoLID project. The two types of PMTs, multi-anode and single-anode, both have advantages and disadvantages. With higher channel density, multi-anode PMTs are more cost effective than single-anode, but it's not possible to control the relative gains of their channels. Single-anode PMTs have more control over their gain, but are easily affected by magnetic fields. We performed a uniformity scan of the multi-anode PMT, which is a measurement of the relative gain of each pixel to make sure the PMT works as the manufacturer specified. The next step was to measure the crosstalk across the PMT. This is the most important part of our research because it tells us if the PMT will be beneficial to the SoLID project.   

Time Resolution Study for CLAS12 Central Time-Of-Flight Detector

The structure of the JLab CLAS12 central-time-of-flight (CTOF) detector requires the use of photomultiplier tubes (PMT) for an accurate ($\sim$ 60 ps) time resolution measurements. The R2083 PMTs used for the CTOF have been modified with a stabilized voltage divider that allows stable performance at high rates and/or gains. The gains of the unmodified PMTs linearly increase with current, up to $\approx $ 400 $\mu $A, where they drop steeply due to a large charge buildup on the last dynode of the PMT accelerating ladder, resulting in a dampening of the electric field in the PMT. From our tests, we saw that the gains of the modified PMTs remained almost constant up to 200-300 $\mu $A. Beyond these they show a similar behavior to the regular PMTs. The modified PMT with the stabilized gain will result in better time resolution measurements at fluctuating count rates, as long as the current in the PMTs is within the range specified previously.   

Multi-Objective Optimization of Heat Load and Run Time for CEBAF Linacs Using Genetic Algorithms

The Continuous Electron Beam Accelerator Facility (CEBAF) consists of two linear accelerators (Linacs) connected by arcs. Within each Linac, there are 200 niobium cavities that use superconducting radio frequency (SRF) to accelerate electrons. The gradients for the cavities are selected to optimize two competing objectives: heat load (the energy required to cool the cavities) and trip rate (how often the beam turns off within an hour). This results in a multidimensional, multi-objective, nonlinear system of equations that is not readily solved by analytical methods. This study improved a genetic algorithm (GA), which applies the concept of natural selection. The primary focus was making this GA more efficient to allow for more cost-effective solutions in the same amount of computation time. Two methods used were constraining the maximum value of the objectives and also utilizing previously simulated solutions as the initial generation. A third method of interest involved refining the GA by combining the two objectives into a single weighted-sum objective, which collapses the set of optimal solutions into a single point. By combining these methods, the GA can be made 128 times as effective, reducing computation time from 30 min to 12 sec. This is crucial for when a cavity must be turned off, a new solution needs to be computed quickly.This work is of particular interest since it provides an efficient algorithm that can be easily adapted to any Linac facility.   

Experimental Setup and Commissioning of a Test Facility for Gain Evaluation of Microchannel-Plate Photomultipliers in High Magnetic Field at Jefferson Lab

At the Thomas Jefferson National Accelerator Facility (JLab) a research and development project for a Detector of Internally-Reflected Cherenkov light for the upcoming Electron Ion Collider is underway. One goal is the development of a compact readout camera that can operate in high magnetic fields. Small-size photon sensors, such as Microchannel-Plate Photomultipliers (MCP-PMT), are key components of the readout. Here we present our work to set up and commission a dedicated test facility at JLab where MCP-PMT gain is evaluated in magnetic fields of up to 5 T, and to develop a test procedure and analysis software to determine the gain. We operate the setup in a single-photon mode, where a light-emitting diode delivers photons to the sensor's photocathode. The PMT spectrum is measured with a flash Analog-to-Digital converter (fADC). We model the spectrum as a sum of an exponential background and a convolution of Poisson and Gaussian distributions of the pedestal and multiple photoelectron peaks, respectively. We determine the PMT's gain from the position of the single-photoelectron peak obtained by fitting the fADC spectrum to the model. Our gain uncertainty is \textless 10{\%}. The facility is now established and will have a long-lasting value for sensor tests and beyond-nuclear-physics applications.   

Evaluation of Multi-Anode Photomultipliers for the CLAS12 RICH

Thomas Jefferson National Accelerator Facility has recently upgraded its Continuous Electron Beam Accelerator Facility (CEBAF) Large Acceptance Spectrometer (CLAS12) to provide a comprehensive study of the complex internal structure and dynamics of the nucleon. The upgrade includes new detectors such as the Ring Imaging Cherenkov detector (RICH) composed of multi-anode photomultipliers (MAPMTs). Our study compared two models of Hamamatsu MAPMTs (H8500 and H12700) under consideration for the CLAS12 RICH in terms of their single photoelectron (SPE) peak, dark current, and crosstalk. The MAPMTs were tested inside a light-tight box, using a low intensity laser to simulate single photoelectron events similar to Cherenkov radiation. The H12700's SPE peaks were on average 78{\%} the width of the H8500's peaks. In both models, crosstalk and dark current were found to be 0.1{\%} to 10{\%} the size of the SPE signal, small enough to be negligible for the purposes of the RICH. The H12700s were found to be superior to the H8500s because they had reduced crosstalk and dark current while providing a narrower peak for single photoelectron events. These results show a promising future for the relatively new H12700 MAPMT in identification of single photon events, and put the CLAS12 RICH on schedule to begin taking data with them in 2017.   

Investigating the Use of the Intel Xeon Phi for Event Reconstruction

The physics goal of Jefferson Lab is to understand how quarks and gluons form nuclei and it is being upgraded to a higher, 12-GeV beam energy. The new CLAS12 detector in Hall B will collect 5-10 terabytes of data per day and will require considerable computing resources. We are investigating tools, such as the Intel Xeon Phi, to speed up the event reconstruction. The Kalman Filter is one of the methods being studied. It is a linear algebra algorithm that estimates the state of a system by combining existing data and predictions of those measurements. The tools required to apply this technique (i.e. matrix multiplication, matrix inversion) are being written using C$^{++}$ intrinsics for Intel's Xeon Phi Coprocessor, which uses the Many Integrated Cores (MIC) architecture. The Intel MIC is a new high-performance chip that connects to a host machine through the PCIe bus and is built to run highly vectorized and parallelized code making it a well-suited device for applications such as the Kalman Filter. Our tests of the MIC optimized algorithms needed for the filter show significant increases in speed. For example, matrix multiplication of 5x5 matrices on the MIC was able to run up to 69 times faster than the host core.   

Testing and Calibration of the Electromagnetic Calorimeter for the Heavy Photon Search Experiment

The Heavy Photon Search (HPS) experiment at Jefferson Laboratory will search for hypothetical massive vector boson, called ``heavy photon.'' The experiment is expected to run in Hall B in the fall of 2014. In this first phase of the measurements, it will search for a heavy photon in the mass range of 20 to 200 MeV/c$^2$. In this mass range the heavy photon will decay into e$^+$e$^-$ pair. An electromagnetic calorimeter (Ecal) will be used to identify electrons and for triggering the readout. The Ecal is made of 442 lead-tungstate (PbWO$^4$) crystals with avalanche photodiode (APD) readout. I will present results from the calibration of cosmic ray testing.   

A Deuteron Quasielastic Event Simulation for CLAS12

An experiment to measure the neutron magnetic form factor ($G^M_n$) is planned for the new CLAS12 detector in Hall B at Jefferson Lab. This form factor is extracted from the ratio of quasielastic electron-neutron to electron-proton scattering off a liquid deuterium ($LD_2$) target. The QUasiElastic Event Generator (queeg) models the internal motion of the nucleons in deuterium. It extends a previous version used at Jefferson Lab.\footnote{J.D.Lachniet, PhD thesis, Carnegie-Mellon University, 2005.} The program generates events that are used as input to the Geant4 Monte Carlo (gemc); a program that simulates the particle's interactions with each component of CLAS12 including the target material. The source code for queeg was modified to produce output in the LUND format, set the position of the center of the $LD_2$ target, and simulate a realistic deuterium target. The event vertex was randomly distributed along the beamline in the target region and von Neumann rejection was used to select random points in the plane transverse to the beamline within a fixed radius from the beam. An initial study of the impact of the target structure and material revealed only limited effects.   

Transverse energy asymmetry in the forward/backward kinematic regions using RHIC beam energy scan data taken by PHENIX

The PHENIX Muon Piston Calorimeter (MPC) is a uniquely situated homogeneous electromagnetic calorimeter that allows, among other things, the study of transverse energy in the forward/backward ($3.1<|\eta|<3.8$) kinematic regions. Transverse energy asymmetries between the North and South hemispheres of the MPC will be studied. Fluctuations in these asymmetries might shed light on the QCD phase diagram of nuclear matter. Nonmonotonic behavior as a function of beam energy would be of particular interest. Accordingly, progress on the analysis of $\sqrt{S_{NN}}$=200, 62.4, 39, and 7.7 GeV Au+Au collisions obtained in 2010 with respect to the aforementioned observables will be reported.   

Transverse energy distributions as a function of pseudorapidity from $\sqrt{S_{NN}}$ = 200 GeV Au+Au Collisions using the PHENIX Muon Piston Calorimeter

While transverse energy at RHIC has been studied extensively at midrapidity, few results have been obtained at forward/backward rapidities. Using data taken by the PHENIX collaboration in 2010, progress measuring transverse energy distributions and $\frac{dE_{T}}{d\eta}$ within the acceptance of the PHENIX Muon Piston Calorimeter (3.1 $<\eta<$ 3.8) will be reported. In addition to estimating the energy density in ultra-relativistic heavy ion collisions, these measurements can be used to distinguish different models of hadronic interactions. In this case, the 2010 data set comprises part of the beam energy scan data taken at RHIC, and the transverse energies as a function of beam energy might signal the existence of a critical point and/or first-order phase transition of the sQGP.   

Developing a High Precision Cosmic Test Stand for PHENIX Research and Development

The multi-purpose Pioneering High Energy Nuclear Interaction eXperiment (PHENIX) at the Relativistic Heavy Ion Collider (RHIC) has been very successful, producing many discoveries. Specifically, PHENIX made critical contributions to the discovery of a new state of matter, the Quark Gluon Plasma (QGP). To allow for the continuation of effective study of the QGP, significant detector upgrades are being developed. A potential upgrade is the addition of high-resolution Time-of-Flight (TOF) detectors. The TOF detectors currently installed in PHENIX have a resolution of about 100ps. To improve the particle identification capabilities of the TOF detectors, an order of magnitude improvement is desired. Possible means of achieving this resolution include Multi-gap Resistive Plate Chamber's (MRPC's) and MicroChannel Plate-PhotoMultiplier Tubes (MCP-PMT's), which are being studied. In order to test these detectors, a cosmic test stand has been commissioned. This test stand includes scintillator triggers, high precision silicon tracking and fast ADCs. To achieve a timing resolution measurement of less than 10 ps, each component in the test stand was chosen carefully. The design and initial results of the test stand will be presented.   

Fluctuations in Transverse Energy at high pseudorapidty using the PHENIX Muon Piston Calorimeter

The PHENIX Muon Piston Calorimeter (MPC) is being used to measure transverse energy fluctuations from Au+Au collisions produced by the Relativistic Heavy Ion Collider (RHIC) in 2010 as part of the beam energy scan program. The PHENIX data set from that year includes Au+Au collisions at $\sqrt{S_{NN}}$ = 200, 62.4, 39, and 7.7 GeV. Nonmonotonic behavior of these fluctuations as a function of beam energy could indicate the existence of a critical point in the QCD phase diagram. Their dependence on collision centrality will also be investigated. Progress in making these measurements with the 200 GeV data will be reported.   

Time of Flight Detector Development for Future Heavy Ion Experiments

Experiments at Brookhaven National Laboratory's Relativistic Heavy Ion Collider discovered the quark gluon plasma (QGP) through the collisions of heavy ions. To further study the the QGP, upgraded detectors may rely on time of flight for particle identification. New techniques are capable of reducing the timing resolution from 100 ps to 10 ps. This improvement will provide better particle identification. Two such detectors that are being considered are multi-gap resistive plate chambers (mRPCs) and microchannel plate photomultiplier tubes (MCP-PMTs). Prototypes of both detectors have been assembled and are ready for detailed testing. In order to test the prototypes, a cosmic test stand has been assembled. To meet the timing resolution goal of 10ps, many details need to be taken into account, including the precise path of a cosmic muon, and the timing resolution of readout electronics. Multiple fast ADCs were considered for this high precision timing study. The chosen ADC was the DRS4 version 5 evaluation board, which has exhibited resolutions as good as 3ps. The status of this research and development project will be presented along with studies of the timing resolution of different electronics that were considered.   

Electrical Characterization of Silicon Photo-Multipliers

Silicon photo-multipliers (SiPM) also known as Multi-Pixel Photon Counters (MPPC)are single photon sensitive, semiconductor devices built from Avalanche Photo Diodes (APDs) working in the Geiger mode. The SiPM detectors provide an attractive solution for the detection of signals with low numbers of photons and are suitable candidates to replace Vacuum Photo-Multiplier Tubes (PMTs). They offer advantages over both PMTs and the APDs, including compactness, insensitivity to magnetic fields, high gain (10\textasciicircum 5), ability to be operated at moderate bias voltage (normally lower than 100 volts), and excellent timing properties these characteristics make them suitable for applications in several fields of high energy physics and medical imaging. At Brookhaven National Laboratory, silicon photo-multipliers have been suggested as the readout device to be used in the upgraded sPHENIX in the area of high-energy physics calorimetry and future Positron Emission Tomography (PET) medical imaging systems. Despite all these advantages SiPMs have several drawbacks such as crosstalk, after pulse rate and dark-count rate, exposure to radiation damages the detector and greatly affects its efficiency. We characterized SiPMs of different pixel sizes from SensL and Hamamatsu to determine the SiPM's performance and which of these detectors would best be suited for application. We characterized these SiPM samples using lab instruments including a Picometer and a digital oscilloscope. A Lab view program controlling and reading out the Keithley Picometer via an IEEE-GPIB interface was developed to automate the dark current as a function of bias voltage measurement.   

Jet Studies on the MPC-EX pre shower detector upgrade to the PHENIX experiment

As a part of the PHENIX experiment at RHIC, we are performing jet studies using the MPC-EX detector. The MPC-EX is pre shower extension to the MPC (the current lead tungstate calorimeter), made up of interleaved Silicon mini-pad detectors and Tungsten plates. This high resolution detector adds tracking and allows for the identification of $\pi^{0}$s and direct photons in the rapidity range 3 $< \eta <$ 4. By studying jet+photon events in simulations of protons on heavy nuclei, we aim to determine how well measurements of the Gluon Structure function can be made by the MPC-EX detector. One of the leading hypothesis to explain gluon distributions at low-x is the Color Glass Condensate.   

An examination of meson versus baryon production in different size collision systems

Quark and gluon hadronization to observable bound states is a process that is not yet fully understood. However, recent high-statistics, multidifferential experimental measurements enable much more detailed studies than previously possible. Interesting differences have been observed in the ratios of baryon to meson production in various collision systems, particularly as a function of transverse momentum. A compilation and analysis of recent results from proton-proton, deuteron-nucleus, and nucleus-nucleus collisions is presented. Identified hadron production in lepton-nucleus collisions is also examined and compared to the hadronic collision data. The comparisons suggest that there may be an additional mechanism for hadronization within certain kinematic regimes in the presence of nuclei, beyond traditionally considered ``vacuum fragmentation'' parameterized by fragmentation functions.   

Heavy Quark Correlations and J/$\psi$ Production in Heavy Ion Collisions

Quark Gluon Plasma (QGP), a phase of QCD matter, was the temporary state that all matter had in the universe microseconds after its creation, which has been produced in high energy nucleus-nucleus collisions at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). Normally being bound inside a proton or neutron, due to the strong nuclear force, the QGP is a hot ``soup'' of quarks and gluons that move relatively freely. QGP is still a very enigmatic state of matter; therefore, active work is being done in trying to understand what is left behind after this short-lived state of matter disintegrates. This includes the abundance of the charmonium meson that consists of a pair of heavy charm and anticharm quarks. In this study, a QGP simulation called the Parton Cascade Model is used with two different initial conditions to see if charm and anticharm quarks can create a charmonium meson in the expanding QGP. In the simulation, the charm quark pair is initially either correlated, with opposite momenta but same position, or uncorrelated, with random momenta and positions, within the QGP. Understanding the difference of the amount of charmonium mesons produced in these two conditions will be helpful in developing theoretical models for charmonium production in heavy ion collisions and thus determining the properties of QGP from experimental measurements.   

Angular Correlation Functions of High pT Charged Hadrons in pp, PbPb, and pPb Collision Monte-Carlo Simulations

The quark-gluon plasma has a role in understanding the strong force, which is described by the theory of quantum chromodynamics. To probe the quark-gluon plasma, heavy ions are collided at high energies to recreate the conditions present in the early universe. Experiments like the Compact Muon Solenoid (CMS) at the Large Hadron Collider examine the results of colliding heavy nuclei together at high energies to recreate the quark gluon plasma. One such observation is jet quenching, which is believed to occur when the jets of particles produced in the collision interact with the plasma and lose energy. In this study, we use the PYTHIA, HYDJET (Hydrodynamics plus Jets) and UrQMD (Ultrarelativistic Quantum Molecular Dynamics) Monte-Carlo simulation programs to observe how the angular correlations of the jets of particles created in collisions vary across the choice of collision system (proton-proton, proton-lead, lead-lead). We will also look at the behavior of these angular correlations to help us understand the mechanisms of energy loss.   

Improved Light Cone Model calculation of strangeness asymmetry in the proton

We expect strangeness in the proton from the Heisenberg uncertainty principle, which allows for the proton to split into a meson and a baryon, such as a K and a $\Lambda$. Our goal is to accurately model the momentum distributions of the strange quarks and anti-strange quarks in the proton. We choose the Light Cone Model because it is a natural explanation for strangeness and for $s(x)$ $\neq$ $\bar{s}(x)$. In the Light Cone Model of Cao and Signal [1], $\alpha$ is a single parameter in the meson-baryon fluctuation functions $f(y)$ and in the $s$ and $\bar{s}$ distributions of the mesons and baryons. These functions are exponentials in which $\alpha$ is related to the spatial extent of the particles. Because the $s$ and $\bar{s}$ are in different environments, we explore an array of values for $\alpha$ which reflect the sizes of the particles and study this effect on our model. We compare our results to global pdfs and experimental data from NuTeV, HERMES and ATLAS.\\[4pt] [1] F. Cao, and A.I. Signal, Phys. Rev. D. 60, 074021, 1999   

Analysis of $s\bar{s}$ asymmetry in the proton sea combining the Meson Cloud and Statistical Model

We investigate strangeness in the proton in a hybrid version of the Meson Cloud Model. The convolution functions used to calculate the $s\bar{s}$ distributions consist of splitting functions and parton distributions. The splitting functions represent the non-perturbative fluctuations of the proton into a strange baryon and an anti-strange meson. The parton distributions of the baryons and mesons are calculated in a statistical model which represents perturbative processes of quarks and gluons. We consider six fluctuation states composed of $\Lambda K^{+}$, $\Sigma^{0} K^{+}$, $\Sigma^{+} K^{0}$, $\Lambda K^{*+}$, $\Sigma^{0} K^{*+}$, $\Sigma^{+} K^{*0}$. We then compare the results of these calculations to other theory, to the NuTeV, ATLAS, and HERMES experiments, and to global parton distributions.   

Investigating strangeness in the proton by studying the effects of Light Cone parton distributions in the Meson Cloud Model

The Meson Cloud Model (MCM) has proven to be a natural explanation for strangeness in the proton because of meson-baryon splitting into kaon-hyperon pairs. Total strangeness is predicted by integrated splitting functions, which represent the probability that the proton will fluctuate into a given meson-baryon pair. However, the momentum distributions $s(x)$ and $\bar{s}(x)$ in the proton are determined from convolution integrals that depend on the parton distribution functions (PDFs) used for the mesons and baryons in the MCM. Theoretical calculations of these momentum distributions use many different forms for these PDFs. In our investigation, we calculate PDFs for K, K*, $\Lambda$, and $\Sigma$ from two-body wave functions in a Light Cone Model (LCM) of the hadrons. We use these PDFs in conjunction with the MCM to create a hybrid model and compare our results to other theoretical calculations, experimental data from NuTeV, HERMES, ATLAS, and global parton distribution analyses.   

Calibrating the STAR Endcap Calorimeter for 2012 Data and Optimizing Tower Gains for 2009 Data

The Solenoidal Tracker at RHIC (STAR), based at Brookhaven National Laboratory, uses polarized $p+p$ collisions to investigate sea quark and gluon contributions to the proton spin. The STAR detector's Endcap Electromagnetic Calorimeter (EEMC) is of particular interest in these experiments because it covers a kinematic region of the detector which is sensitive to gluons carrying a low fraction of the proton momentum, where the gluon spin is almost entirely unconstrained. The EEMC is located in the intermediate pseudorapidity range $1 < \eta < 2$, and measures the electromagnetic energy of particles produced in the collisions using a spatially segmented lead-scintillator sampling calorimeter. Each segment, or tower, is energy-calibrated using minimum ionizing particles. Scintillator light is converted to an electric pulse whose height is proportional to the energy deposited in the tower. A gain factor that converts the pulse height to energy deposited in GeV is determined separately for each tower. An independent energy calibration method was used to fine tune the tower gains and attempt to address other potential sources of systematic uncertainty, such as pseudorapidity-dependence in the reconstructed $\pi^0$ been started. Results from the 2009 and 2012 calibrations will be presented.   

Measurement of pion elliptic flow with BBC event planes in Au$+$Au collisions at $\surd $s$_{\mathrm{NN}} = $ 7.7, 11.5 and 19.6 GeV

The quark gluon plasma (QGP) formed in high-energy heavy-ion collisions at RHIC top energies is a strongly interacting medium. Elliptic flow ($v_{2})$, which is the second-order Fourier coefficient of the azimuthal distribution of the produced particles with respect to the reaction plane, has been extensively used to study this medium's properties. Previous STAR data showed a difference in $v_{2}$ of $\pi^{+}$ and $\pi^{-}$ that becomes more pronounced at lower collision energies such as $\surd$s$_{\mathrm{NN}} = $ 7.7 GeV [1]. In this poster, we analyze $v_{2}$ of $\pi^{+}$ and $\pi^{-}$ produced at mid-rapidity, with the event plane reconstructed from the STAR Beam Beam Counters (BBC). With the pseudo-rapidity gap ($\Delta \eta $ \textgreater 2) between the event plane and particles of interest, we improve our control of the systematics due to the short-range correlations that are not related to the reaction plane. The low possibility of proton registration in the BBC further suppresses the background due to weak decays. We will present pion $v_{2}$ results for Au$+$Au collisions at 7.7, 11.5 and 19.6 GeV, and discuss the physics implications of our results in comparison with previous data whose event plane was reconstructed at mid-rapidity.\\[4pt] [1] L. Adamczyk \textit{et al.}, Phys. Rev. Lett. \textbf{110} (2013) 142301.   

Neutral Pion Asymmetries at Intermediate Pseudorapidity in Transversely Polarized $p+p$ Collisions at $\sqrt{s}=200$ GeV

Among the unanswered questions pertaining to nucleon spin physics is the origin of large azimuthal asymmetries ($A_{N}$) found in $\pi^{0}$s produced at forward pseudorapidity, $\eta$, from high-energy transversely polarized $p+p$ collisions. One possible explanation is offered by twist-3 parton distribution and fragmentation functions. In order to test these and other mechanisms, it is important to study how the asymmetry changes over a range of pion kinematics. The STAR Endcap Electromagnetic Calorimeter (EEMC) is the only RHIC detector with the ability to study $A_{N}$ for $\pi^{0}$s in the kinematic range available at intermediate pseudorapidity, $0.8\leq\eta\leq2$. STAR recently published the first measurement of $A_{N}$ for $\pi^{0}$s at intermediate pseudorapidity using data collected in 2006 with collision energy $\sqrt{s}=200$ GeV. In 2012 STAR collected a high-statistics dataset with transverse beam polarization at $\sqrt{s}=200$ GeV. This offers over a five-fold increase in integrated luminosity relative to the 2006 dataset and a chance to enhance the precision of the previous results. The primary objective of this study is to determine the quality of the data from 2012 and to estimate the final statistical uncertainty.   

An examination of STAR 2012 $\pi^0$ data at $0.8 < \eta < 2.0$ with longitudinally polarized $\overrightarrow{p}$ + $\overrightarrow{p}$ collisions at $\sqrt{s}$ = 510 GeV

A recent global analysis of the proton spin has provided evidence for positive gluon polarization $\Delta$g(x) for the momentum fraction range of $0.05 < x < 1$. The region $x < 0.05$ remains relatively poorly constrained, and may provide a significant contribution to the spin of the proton. The STAR detector can be used to measure the effects of quark and gluon spins in the proton through the measurement of asymmetries in $\pi^0$ production for different polarization states. The Relativistic Heavy Ion Collider at Brookhaven National Laboratory is uniquely able to collide polarized protons. Data from the $\overrightarrow{p}$ + $\overrightarrow{p}$ run in 2012 has significantly higher integrated luminosity and at a center of mass energy of 510 GeV, higher than previously analyzed datasets, thus allowing better access to $\Delta$g($x$) at low $x$. The STAR endcap electromagnetic calorimeter, or EEMC, is able to detect $\pi^0$'s in the range of pseudorapidity $0.8 < \eta < 2.0$, a region at this energy where $\Delta$g($x$) for low $x$ can be examined. Preliminary work on 2012 data will be shown.