Bulletin of the American Physical Society
2021 Fall Meeting of the APS Division of Nuclear Physics
Volume 66, Number 8
Monday–Thursday, October 11–14, 2021; Virtual; Eastern Daylight Time
Session GA: Conference Experience for Undergraduates Poster Session I (4:00 - 5:15 pm) |
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Room: Poster Room East |
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GA.00001: Enhancing Photon-Gluon Fusion Process in $e$ + $p$ and $e$ + A Two-Particle Correlations. Yifan Yuan Two-Particle correlations have been a very useful probe to study the gluon dynamics in hadronic collisions. It is expected to be an important probe of the saturation for low-energy gluons. Therefore, as the new Electron-Ion Collider (EIC) will be built at Brookhaven Laboratory, studies of di-hadron correlations in electron-proton and electron-ion collisions are essential. In deep inelastic scattering at high $Q^{2}$, the gluon wavefunction can be probed by measuring the Photon-Gluon Fusion process. By separating out the Photon-Gluon Fusion of $e$ + $p$ and $e$ + A events, a cleaner signature of gluon saturation and gluon distribution function is possible. In this poster, we show the results of a DJANGOH study to separate the Photon-Gluon Fusion from other processes that contribute to Two-Particle Correlations. |
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GA.00002: A New Reaction Plane Detector for ATLAS Heavy Ion Physics Program in Run 3 Farah D Mohammed Rafee The ATLAS Zero Degree Calorimeter (ZDC) is installed in the Target Absorber for Neutrals of the Large Hadron Collider (LHC) during the Heavy Ion data taking. Each of the two ATLAS ZDCs comprises one electromagnetic (EM) and three hadronic (HAD) modules. By measuring the energy deposited by spectator neutrons, the ZDC can determine the spectators’ multiplicity and therefore the event’s centrality. |
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GA.00003: Assessing performance of the STAR detector during the 2017 510 GeV proton-proton run Madison Meador Over the past 20 years, the Solenoidal Tracker at RHIC (STAR) at Brookhaven National Laboratory has been a leading experiment in investigating the complex spin structure of protons through high energy collisions of proton beams, for example, using distributions of pions in jets to probe transversity. In 2017, STAR collected a high-statistics dataset from transversely polarized proton-proton collisions at the center-of-mass energy of 510 GeV. An important first step in the analysis of the 2017 data is assessing the quality of the data, in particular, through studying the stability of several sub-systems throughout the duration of the RHIC run. By tracking detector-level information for each run, STAR can identify a list of high-quality runs for physics analyses. This presentation will show a selection of detector- level stability plots relevant for future analyses of pions in jets, e.g., energy deposition in towers of the electromagnetic calorimeter, momenta of charged-particle tracks from the time projection chamber, and particle-identification information measured in the time-of-flight detector. |
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GA.00004: Assessing the Performance of the STAR Forward Calorimeter SystemNoah MitchellAbilene Christian University, Abilene, TexasFor the STAR Collaboration Noah Mitchell The STAR experiment studies phenomena like nuclear matter and nucleon structure through the collisions of heavy ions and spin-polarized protons. To further these objectives, the STAR forward upgrade was commissioned and started taking its first data in 2021. One of the goals of our 2021 run has been testing the Forward Calorimeter System (FCS), which includes electromagnetic and hadronic calorimeter systems. This system is equipped with an LED system for monitoring purposes. One aspect of the testing has been looking at the pedestal (PED) and LED pulse height data to ensure the systems are working properly. This presentation will provide examples of ratio plots of PED RMS, as well as the LED, over the course of several runs to ensure the long term stability of the systems. |
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GA.00005: A model for the production of double quarkonium in PbPb collisions at √sNN = 5.02 TeV Miles Cochran-Branson, Manuel Calderon de la Barca Sanchez We model the uncorrelated production of double quarkonium (γ and J/ψ mesons) in Pb+Pb collisions at √sNN = 5.02 TeV through implementation of a standard Monte Carlo Glauber model and a Monte Carlo particle production simulation, PYTHIA 8.306. A multinomial model, using probabilities obtained from relevant literature as well as from a PYTHIA simulation, was used to obtain estimates of double quarkonium yields corresponding to an integrated luminosity of L = 1.7nb-1 collected by CMS in the 2018 PbPb run. Distributions from PYTHIA for the γ and J/ψ mesons and their daughter muons were used to calculate acceptance, and muon efficiencies were obtained from studies done in CMS. Estimates of the probability of production for the γ and J/ψ mesons were made from these values. The estimates of double quarkonium production can be used for comparison to future measurements to be performed at the CMS detector. |
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GA.00006: Optimization of Selection Criteria for B→D(*)ηl+νl Anna V Costelle, Anselm Vossen, Frank Meier The Belle experiment and its successor, Belle II, study B-mesons produced via e+e- annihilation near the Υ(4S) resonance. Precise measurements of B-meson decays are important for our understanding of flavor-mixing and may yield insight into physics beyond the standard model. An interesting anomaly is the significant discrepancy between inclusive and exclusive measurements of the B→Xclν branching fractions. One possible decay mode that could bridge this gap is B→D(*)ηl+νl. In this work, we use a boosted decision tree (BDT) to select the products of this semi-leptonic decay. We first seek to distinguish signal from background using variables that describe η and its subsequent decay to γγ. We determined discriminating input variables using simulated signal and background samples. Furthermore, BDT hyperparameters were tuned to minimize overtraining and maximize background rejection as a function of signal efficiency. This method notably improved the signal purity compared to a cut-based approach. |
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GA.00007: Jason Spriggs HEP RIVET Abstract Jason A Spriggs When high energy nuclear collisions result in the creation of a quark gluon plasma (QGP), hard partons scattered in the collision lose energy as they traverse the QGP. This can be observed using two-particle collisions. Data from the Relativistic Heavy Ion Collider are compared to Monte Carlo models using analyses developed in the Robust Independent Validation of Experimental and Theory (RIVET) program. The RIVET analyses were used to compare the data to PYTHIA Angantyr and JETSCAPE. The formatting of the raw data from the collisions and the creation of the RIVET analysis were integral to the process of interpreting the data. Measurements of two-particle correlations will be emphasized. |
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GA.00008: Examining the relationships between charged-particle spectra and event centrality in oxygen-oxygen collisions using the STAR detector at RHIC Jordan R Cory High energy collisions of heavy ions form a relativistic hydrodynamic fluid called the Quark Gluon Plasma (QGP). Central collisions, collisions that have a small impact parameter, produce larger volumes of QGP than peripheral collisions with a larger impact parameter. One way of studying the QGP is by comparing the momentum spectra of charged particles in central and peripheral collisions. Traditionally at the Solenoidal Tracker at RHIC (STAR) experiment, centrality is determined via charged particles at mid-rapidity within the Time Projection Chamber (TPC). This measure of centrality could suffer from auto-correlation if the charged-particle spectra are measured in the same phase space. To mitigate this effect, centrality can also be estimated using the charged-particle multiplicity measured in the Event Plane Detector (EPD), covering a pseudorapdity range of 2.1<|η|<5.1. This poster will compare the charged-particle momentum distribution ratios obtained by using the two different methods of estimating collision centrality in oxygen-oxygen collisions at a center-of-mass collision energy of 200 GeV per nucleon pair. Such a comparison will help us explore the inherent correlations between particle production across different regions of heavy ion collisions. |
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GA.00009: Using Generative Adversarial Networks to biaxially unfold Beta-Oslo Matrices Cade T Dembski, Artemis Spyrou, Sean N Liddick, Michelle P Kuchera, Raghu Ramanujan We explore the use of Generative Adversarial Networks (GANs) to biaxially unfold Beta-Oslo matrices to compute neutron capture cross sections. The Beta-Oslo method, for which the matrices are named, is a technique used to simultaneously extract the Nuclear Level Density and gamma-strength function of neutron-rich nuclei. These properties are important to the calculation of the neutron capture cross section, a nuclear parameter with particular relevance to r-Process nucleosynthesis reaction network calculations. However, the current method for unfolding Beta-Oslo matrices is uniaxially restricted, constraining the amount of information available for analysis. GANs, a state of the art generative modeling technique based on recent advances in deep learning, approach biaxial unfolding as an image-to-image translation problem. Preliminary results from training a Pix2Pix GAN architecture with Beta-Oslo matrices simulated based on the response of the SuN total absorption spectrometer indicate that gamma ray energies can be extracted within a resolution of 6%. |
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GA.00010: Development of a Monte Carlo Generator for the Bethe Heitler Process Brenna Petrelli The study of the nucleon structure in terms of Generalized Parton Distributions via Deeply Virtual Compton Scattering has been the focus of an extensive experimental program at many laboratories such as Jefferson Lab. When measuring DVCS, the Bethe Heitler process dominates the cross section and contributes to the spin asymmetries by interference, therefore a full understanding of the Bethe Heitler process is essential for DVCS measurements. Of particular interest is the calculation of Bethe Heitler for the deuteron. For this purpose I have developed a Python program to calculate Bethe Heitler of the deuteron for all polarizations using the formalism in [2] and new calculations [1]. I will present the dependence of the Bethe Heitler cross section in terms of the four independent variables - the four-momentum squared of the virtual photon Q2, the four-momentum squared that is transferred from the initial to the final deuteron (t), x Bjorken (xBj), and the angle between the leptonic and hadronic planes (Φ). In addition, I will discuss the phase space and kinematic limits for this process. Ultimately, this work will be used to develop a Monte Carlo generator to be used with the CLAS12 simulation to study coherent DVCS acceptance. |
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GA.00011: Google Colaboratory for Partial Wave Analysis at GlueX Balin Armstrong The GlueX experiment at Jefferson Laboratory aims to study the meson spectrum produced from a high-energy beam of photons incident on a liquid hydrogen target and perform amplitude analysis to identify the intermediary particles produced by the collisions. This research explored using Google Colaboratory (Colab), a Jupyter Notebook environment provided by Google, to do partial wave analysis (PWA) for the GlueX experiment. Using Colab, the reaction γp → ωπ0p was studied and a PWA was performed without the use of a high-performance cluster. The PWA determines the quantum mechanical amplitudes that contribute to this reaction by modeling the intensity distribution as a function of the decay angles of the produced mesons. Initial results from this PWA will be presented, demonstrating that analysis such as this can be done with Colab instead of a high-performance cluster. We hope the programs created for this project will make PWA more accessible to those with limited coding experience. |
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GA.00012: Analysis and Validation of Reconstruction Resolution for CLAS12 Ryan J Sanford, Gerard P Gilfoyle, Adrian Saina, Veronique Ziegler The CLAS12 detector at Jefferson Laboratory measures electron-nucleus scattering and requires a complex reconstruction code. The reconstruction resolution is extracted from the difference between the reconstructed trajectory of a particle and a 'true' trajectory (from simulation) to understand and improve the CLAS12 performance. Events are simulated with the physics-based code gemc and reconstructed with the CLAS12 Common Tools. We then start at the reconstructed track vertex and swim a track starting with the known momentum before the simulation. A second track is swum from the same starting point with the reconstructed momentum. We take the difference between points where the two tracks intersect CLAS12 subsystems and fit the distributions to obtain the widths/resolutions for the observables x, y, z, , , and b (b is the distance between points where the tracks intersect the front face of the detector subsystems). We plot the resolutions versus the positions of the detector subsystems. As particles go through more layers of CLAS12, the reconstruction resolution increases. We also see that after a gemc upgrade to make the code more realistic, the resolutions increased by about 50% on average and were more consistent with measured data. |
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GA.00013: Simulation of Neutron Detection Efficiency in the CLAS12 detector Jessie O Hess, Lamya Baashen, Gerard P Gilfoyle The neutron magnetic form factor is a fundamental observable that will be measured with the CLAS12 detector at Jefferson Lab. This measurement requires precise knowledge of the CLAS12 neutron detection efficiency(NDE). We determine the NDE by measuring the ratio of neutrons detected versus neutrons expected. We use the nuclear reaction (ep->e'n π+)-electron beam(e) on a proton target(p) producing an electron(e'), neutron(n), and a pion(π+). We apply momentum conservation to the e'π+ system to predict the neutron trajectory. We swim the neutron track to see if it strikes the fiducial volume of CLAS12. If it hits, we increment the NDE denominator for that neutron momentum. Otherwise the event is excluded. For good events we then search for and identify a neutron hit near the predicted position. If it is found, we add it to the NDE numerator. We generated events using Pythia, simulated them in CLAS12 with the physics-based Monte Carlo code GEMC, and reconstructed them using the CLAS12 Common Tools. We added background events to study their effect on the NDE ratio. We wrote a groovy script to analyze the data and extract the NDE. The NDE is small at low momenta and at a momentum of approximately 0.5 GeV it rises to a plateau at an efficiency of about 70%. |
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GA.00014: Coordinate Space Representation of Quark and Gluon Generalized Parton Distribution Functions Zaki Panjsheeri, Philip Velie, Brandon Kriesten, Simonetta Liuti, Krisean Allen Two-dimensional Fourier transforms of generalized parton distributions (GPDs) provide insight into matter, charge, and radial distributions of the quarks and gluons inside the nucleon. We present an explicit calculation of such transforms in a spectator model framework using parametric analytic forms of GPDs, originally constrained using deeply virtual Compton scattering and lattice QCD data. Our calculations were performed for several values of the momentum fraction X and evolved using perturbative QCD from the initial scale Q0 to the scale of the data. We studied the effect of evolution, the difference between matter and charge density in both the proton and the neutron, and the location of the gluon distribution relative to the valence quarks. |
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GA.00015: Studying hard exclusive production of heavy vector mesons to access the Generalized Parton Distributions of protons Marie Boer, Tyler Schroeder Heavy meson production is a key tool for accessing the Generalized Parton Distributions (GPDs) of protons. GPDs are functions that correlate the partons’ longitudinal momenta and their transverse distribution. The Hard Exclusive Production of Quarkonia (J/ψ, Υ...) is particularly interesting as it accesses the gluon GPDs at the lowest order in QCD. |
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GA.00016: Behavior of light and dark scattered neutrons in MoNA bars in comparison with simulation olivia guarinello, Ari Maki, Anthony N Kuchera The Modular Neutron Array (MoNA) is a high-efficiency neutron detector and powerful tool for studying exotic nuclei approaching the neutron dripline. In order to test and improve the simulation of nuclear interactions imperative to this study, the MoNA Collaboration has performed experiments at the Los Alamos Neutron Science Center (LANSCE) and observed neutron scattering using sixteen BC-408 plastic scintillator detectors exposed to a well-characterized neutron beam of ranging energies. A previous experiment using the MoNA bars featured compact detector geometry and resulted in disagreement between two simulation packages (Geant4 and Menate_R) and experimental data. It also provoked the need to improve understanding of dark scattering, or elastic scattering from carbon nuclei that produces insufficient light for detector thresholds. In this experiment the MoNA bars were reconfigured into a staircase array and target bar with the goal of increased angular resolution and bar separation required to estimate the location of the first hit in dark scattering. Features of neutron scattering, such as angular distributions, hit multiplicities, and energies of the scattered neutrons were analyzed and compared with simulation and will be presented. |
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GA.00017: Towards a High Precision Investigation of the Strange Form Factor of the Proton: A Study of the Shift in Detector Signal for Polarized Protons in Matter Austin Blitstein, Bogdan B Wojtsekhowski Recently, the parity violation present in polarized electron-proton elastic scattering has been used to obtain information about the pairs of virtual strange quarks within the proton. It is thought that a measurement of the corresponding strange form factor at a momentum transfer Q2 of 3 (GeV/c)2 could be large, a potential discovery. To succeed with such measurements, it is necessary to create a large solid angle detector to track the angular correlation between scattered electrons and recoil-protons. The current proposal suggests the use of calorimeters, and requires detector efficiency to be independent of the electron beam polarization. However, the polarization of the recoil-protons induces a spatial shift in detector signal due to spin-dependent interactions within the calorimeter. If the shift is too large, the cuts made in data analysis cease to be polarization independent. We found using Geant4 that such a shift is approximately 16±1 μm (statistical), which is sufficiently small for the purposes of the proposed experiment. This result allows us to start work on the proposal to the JLab PAC and the design of the experiment. |
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GA.00018: Hydrodynamic Attractor of a Viscous Fluid in an Expanding Universe Alex Lu, Jorge Noronha, Maurício Hippert The Israel-Stewart theory of relativistic hydrodynamics is a prominent tool often used to study heavy ion collisions and, under certain conditions, has been shown to be causal and well-posed when coupled to gravity. We study an Israel-Stewart theory of relativistic fluids with bulk viscosity coupled to Einstein's equations in a Friedmann-Lemaître-Robertson-Walker (FLRW) expanding universe. Solutions to these equations are found to converge to two attractors corresponding toearly times and late times. We perform a numerical analysis of these attractors and compare theresults to an analytical solution found using a slow roll approximation. The fluid is found to reach a stable out of equilibrium value as the universe tends to a fixed rate of expansion. |
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GA.00019: Relativistic Contributions to One-Body and Two-Body Electromagnetic Current Operators in D(e,e'p) Reactions Andrew J Smith, Sabine E Jeschonnek We reproduce the results from a study [1] of the non-relativistic reduction of the one-body portion of the electromagnetic current operator, and then extend this approach to pieces of the two-body current. The traditional approach to this problem has been to make approximations for the transferred energy, transferred momentum, and initial momentum of the struck nucleon in order to obtain an on-shell, positive-energy form for the current operator. In [1], the transferred energy and momentum were treated exactly, leaving only an expansion in the initial momentum of the struck nucleon. Here, we extend this approach to two-body current pieces in exclusive electron scattering from the deuteron, following [2]. We discuss the numerical relevance of the relativistic effects in D(e,e'p) reactions for different kinematics. |
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GA.00020: Studying Charged Particle Interaction Modeling with Theoretical Computational Field Solvers Tracy S Blade In the field of physics, biology, chemistry, and engineering, the question of how many particle systems interact with each other is often pondered. Now, with the strength of computer science and our knowledge of physics, we can now approach this question fully by developing methods that integrate these two fields. Specifically, there are several ways in which this can be accomplished. In general, we want to understand how charged particles interact with each other given their own intrinsic properties and how they affect their surroundings, i.e. charged particles generate electric fields which act as forces that draw and/or pull. Often, you are examining this physical phenomena for a number of particles in the billions. Obviously, this is a large quantity of particles, and has thus provided motivation for developing field solvers. The field solvers in question are Particle in Cell (PIC) and the Fast Multipole Method (FMM), along with the most naive approach, direct calculation. The basis of this project on which these field solvers will be constructed consists of developing a simulation of particles, generally called source particles, on a grid composed of evenly spaced nodes. These grid nodes will be used as a reference when considering what effect these particles have on its surroundings. Furthermore, High Performance Computing (HPC) will also be used to further investigate the efficiency and accuracy of these methods. This research can impact the field of nuclear physics as we can now further examine beam quality, which is used to probe the nucleus of atoms. Additionally, the development of these field solves can be applied to many body problems in nuclear physics, as well. |
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GA.00021: Modeling the Production of Electron-Positron Pairs Samuel J Brown, Thomas Settlemyre, Aldo Bonasera When studying particles with masses between 1 MeV to 100 MeV, the lack of high precision theory coupled with difficulties in experimental measurements makes studying particles with masses less than 1 MeV of significant importance. This lack of understanding promotes interesting questions in the production of these particles. Particular to this research, the study of electron-positron-pair production in the strong field has the ability to provide insight into particle production with masses less than 1 MeV. Studying electron-positron production requires kinematic modeling of collisions of non-relativistic ions such as \(^{238}U\) and \(^{12}C\). This research works to create dynamic kinematic models to track the motion and momentum of all atoms and leptons in the system. Due to the changing Coulomb potential between the colliding ions during electron-positron pair production, this sort of kinematic modeling is carried out numerically, employing standard integration and modeling algorithms such as Taylor expansion integrations and Monte-Carlo sampling. |
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GA.00022: Abstract Withdrawn
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GA.00023: Polarized Ultracold Neutrons and Spin Analysis in the LANL nEDM Experiment Alicen M Houff The neutron Electric Dipole Moment (nEDM) experiment at the Los Alamos National Laboratory aims to achieve an improved level of precision of the neutron dipole moment. Our experiment would yield a sensitivity of |dn|~ 3x10-27 e-cm, 10 times better than the current upper limit of |dn| ~ 3x10-26 e-cm. To reach these values, the experiment requires polarized ultracold neutrons (UCN) to be transported into a magnetically shielded room (MSR), in which a highly uniform B0 field (1~micro T) is applied to perform Nuclear Magnetic Resonance (NMR) measurements. The spin state of the neutrons entering the MSR is prepared by a 6~T superconducting magnet, and the final spin states (after NMR) are analyzed using a simultaneous spin analyzer system. The spin analyzer determines the spin state of neutrons by transmitting through an iron foil, fully magnetized by NdBFe irons, and a RF field to flip the spin states; the transmitted neutrons are captured in a 10B coated ZnS scintillator and counted by PhotoMultiplier Tubes (PMT). In my talk, I will discuss the methods used to improve the nEDM sensitivity limit in our experiment and report the progress on the construction, focusing on the implementation of the spin analyzer. |
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GA.00024: Magnetic Shielding in the nEDM Experiment at Los Alamos National Laboratory Greg M Gill The search for the neutron electric dipole moment (nEDM) is an ongoing project at Los Alamos National Laboratory (LANL) with the intention to improve measurement precision using techniques of room-temperature Nuclear Magnetic Resonance (NMR). The current accepted upper limit of the nEDM is |dn| < 1.1 · 10−26 e·cm recently published by the Paul Scherrer Institut group (2020). The nEDM@LANL effort looks to improve the measurement uncertainty to 3 · 10−27 e·cm. A non-zero nEDM result of this sensitivity will suggest CP-violating physics beyond the Standard Model that will further our understanding of the matter-antimatter asymmetry of the universe. In order to reach this sensitivity, a magnetically shielded room (MSR) is necessary. The MSR is currently under construction at LANL; it consists of five independent layers: one layer of copper and four layers of MuMetal, an alloy with a high magnetic susceptibility. The MSR is expected to produce a shielding factor of 100,000 at 0.01Hz. In this poster, I will discuss the design principle and report on the construction of the MSR. |
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GA.00025: Neutron Inelastic Scattering of 76Ge Coincidence Analysis Kaitlyn Kidwell, Mary F Kidd, Werner Tornow, Sean W Finch In the study of neutrinoless double beta decay of 76Ge, the potential background events need to be fully understood. One potential background comes from neutrons, specifically neutron inelastic scattering. The de-excitation of the 76Ge nucleus could produce gamma rays in the double beta decay region of interest at 2039.061 keV. Camp and Foster [1] first measured an excited level in 76Ge with an energy of 3951 keV, which de-excites with the emission of a 2040.70 keV gamma ray. In a 2015 study by Crider et al. [2], they investigated neutron inelastic scattering on 76Ge with 3.7 MeV neutrons. They did not observe the 2040 keV gamma ray, and instead, they placed a level at 3147 keV and observed a 2038 keV gamma ray emission. We have extended this neutron inelastic scattering measurement to 4.5 MeV incoming neutrons at Triangle Universities Nuclear Laboratory. In our current study, we investigate the production of the 3147 keV level by creating coincidence spectra at 2038 keV - 1108 keV, 2041 keV - 1911 keV, 2583 keV - 562 keV, and 2579 keV - 562 keV. |
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GA.00026: Characterization of Silicon Photomultipliers for nEXO Natalya Pletskova Neutrinos are constantly bombarding us, but their interactions are so weak that studying their properties, including their fundamental nature, can be challenging. Neutrinoless double beta decay (0vββ) is a rare nuclear process that can shed light on the matter-antimatter nature of neutrinos. The next-generation nEXO experiment is a planned experiment that would use 5000 kg of isotopically enriched liquid xenon in a time projection chamber to look for 0vββ in 136Xe with a target half-life sensitivity of about 1028 years. nEXO plans to use SiPMs as photosensors to detect liquid xenon scintillation light because they are radiopure devices operated at low voltages with high gain. My objective is to characterize SiPMs at cryogenic temperature and ensure that this application will achieve the nEXO goal of ~1% energy resolution at the Q-value of 0vββ of 136Xe. |
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GA.00027: Convolutional Neural Networks to Classify Single and Double Electron Events for the Majorana Demonstrator Alexander Stewart In the search for neutrinoless double beta decay (0ν2β), single electron events in the Ge-76 detectors of the MAJORANA DEMONSTRATOR and future LEGEND project degrade our ability to measure the decay rate of 0ν2β decay. If we can find a way to filter out single electron events from our dataset, we can remove a significant portion of the background noise in our system. We demonstrate that through the use of convolutional neural networks (CNNs), simulated single and double electron events in P-Type point contact (PPC) Ge detectors can be classified with an area under the curve (AUC) of 0.822, meaning 82.2% of the time the CNN can differentiate between a single and double electron event based solely on the normalized simulated waveform. |
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GA.00028: Abstract Withdrawn
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GA.00029: Spin without Magnetism: Neutron Scattering in search of a Fifth Force Lilian M Lommel, Joshua C Long, William M Snow, Caleb D Hughes, David Baxter Current experimental limits allow for unobserved, fundamental forces of nature many times stronger than gravity at sub-millimeter length scales. Such forces arise in unified theories, and could be mediated by candidate particles for dark matter and dark energy. These forces can couple to fundamental properties such as mass and spin. Constraints on spin-dependent interactions are less stringent given the difficulty of producing polarized test masses in the absence of magnetic fields which can lead to backgrounds, and constraints on momentum-dependent interactions are even weaker. We describe an experiment designed to search for exotic spin and momentum-dependent interactions between neutrons and electrons. The experiment uses polarized neutron spin rotation, which has emerged as a powerful technique to probe fundamental interactions down to the micron range. The polarized scattering target consists of a rare-earth iron garnet that exhibits orbital compensation of the magnetism associated with the electron spins. The compensation is expected to be greatest near temperatures of 250 K. We describe the target fabrication and cooling apparatus in detail, and discuss the projected sensitivity of the experiment. |
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GA.00030: Understanding the Dead Layer: Examining experimental conditions affecting proton energy loss Michelle McKenzie, Leah J Broussard, Michael T Gericke, Francisco M Gonzalez, Nicholas Macsai, Russell R Mammei, David Mathews The Nab experiment at the Spallation Neutron Source will precisely characterize neutron beta decay to further understand the weak interaction. It uses an asymmetric, magnetic spectrometer with an unpolarized cold neutron beam to measure the correlation, a, between the electron and the antineutrino. By means of the conservation of momentum, this correlation only requires the detection of proton momenta and electron energy. These measurements are performed by using silicon detectors to determine the decay proton's momentum and decay electron's energy. The "dead layer" at the entrance of the detector is unable to produce detectable energy signals, thus resulting in proton energy loss. In poor vacuum conditions, there could be a gradual increase in the build-up of frozen particles on the detector, which could expand the effective dead layer. If the dead layer increases with time, that will decrease the detected proton energy and therefore the accuracy of the Nab results. I will discuss measurements of the proton energy as a function of detector cooling time, the possible relationship to an increased dead layer, and the implications for the Nab experiment requirements. |
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GA.00031: Design and construction of a Modular NaI(Tl) Detector Array for use in the Parity-and Time Reversal Violation Measurements for NOPTREX Jon Mills The goal of the NOPTREX experiment is to probe the Standard Model via parity and time reversal invariance violation in low energy neutron-nucleus resonances. An array of modular NaI(Tl) detectors with fast timing and good energy resolution is needed to measure asymmetries in the total forward scattering cross section, and in the gamma from neutron capture on deuterium. These detectors will be designed to operate in both pulse and current modes. A search for parity violation in A>120 nuclei and also in the reaction n+d -> t+gamma is being carried out in the FP12 instrument at the Los Alamos Neutron Science Center. We will discuss an efficient design of the detectors, electronics, and magnetic shielding, |
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GA.00032: Assessment of a Nitrogen-Vacancy Magnetometer for Use in Precision Ultracold Neutron Experiments Cameron A Shepherd The UCNτ experiment aims to improve current measurements of the mean free neutron lifetime. |
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GA.00033: Death of the Free Neutron: too much pressure? Alejandro A Cepero, Nadia Fomin, Jimmy Caylor The neutron lifetime is a quantity that is important for the Standard Model of Particle Physics as well as Big Bang Nucleosynthesis calculations. The BL2 Experiment looks to measure the lifetime of a free neutron using the beam method, which aims to count the amount neutrons that have decayed. The data taken includes protons being captured by an electrode trap from the decayed neutrons, as well as neutrons that pass through the trap by a neutron flux monitor. The pressure inside the experiment is monitored continuously by pressure gauges on the apparatus, and fluctuations could affect the behavior of the trapped protons. The pressure data will be presented, and correlations with proton detector signals will be examined. |
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GA.00034: Abstract Withdrawn
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GA.00035: Be and Li ion production via laser ablation for experiments to investigate the nature of the neutrino Dakota Keblbeck The investigation of neutrinos is an important part of understanding physics beyond the Standard Model. One experimental approach, beta decay studies, provides information on the particle nature of the neutrino, its absolute mass, and on the existence of sterile neutrinos. These types of experiments often require precise Q values of the beta decays, to aid in analyzing and interpreting results. One example is the BeEST experiment, which uses the electron capture decay of 7Be, to search for signatures of keV scale sterile neutrinos. Penning trap mass spectrometry (PTMS) is the most precise method for determining the Q value, by measuring the mass ratio of the parent and daughter atoms. A key part of PTMS experiments is the successful implementation of an efficient and reliable ion source. At Central Michigan University, we are investigating our laser ablation ion source as a means of producing 9Be and Li ions, for future CHIP-TRAP experiments that aim to measure the 7Be Q value more precisely. More specifically, we are investigating 9Be+ ion production using a solution of beryllium dissolved in HCl and dried out on a backing target material. This will act as a proxy for the suggested method of producing 7Be+ ions from the available 7Be from the National Isotope Development Center. |
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GA.00036: Electron-Positron Annihilation Lifetime Spectroscopy of MgO Elise Liebow, Heather Watson
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GA.00037: Abstract Withdrawn
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GA.00038: Optimizing Energy and Timing Resolution of GAGG Scintillators with SiPM Readout for a Time-Reversal Experiment Michelle Khoo, John A Behr, Tine Valencic TRIUMF’s Neutral Atom Trap (TRINAT) is probing for time-reversal symmetry in beta-neutrino-gamma coincidences. Since the scalar triple product of these momenta flips sign with time, a time-reversal violating interaction would produce a non-zero average value. GAGG (Gadolinium Aluminium Gallium Garnet) scintillators offer high average Z and density (6.6 g/cm3), which is useful for compact and efficient detection of MeV gammas. In addition, this scintillator is non-radioactive, which is needed to reduce random coincidence background. Two GAGG detectors require optimized energy resolution and timing resolution in the presence of dark current from the SiPM readout. FWHM energy resolution of ≈7% at 1332 keV and FWHM timing resolution of ≈8 ns has been achieved so far. In this poster, the detector setup and recent improvements to its electronics and optical design will be described. |
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GA.00039: Rotational Structure in Nuclei Near 66Fe Emma Rice, Heather L Crawford Studies of the "heavy" island of inversion near the N=40 isotones between Ca and Ni have, to date, focused on determining the degree of collectivity in even-even nuclei using properties of 2+ transitions. While collective rotational structures are understood to be present, limited results are available to characterize these structures. In this work, we report on the results from an experiment conducted at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University (MSU) using a secondary fragmentation reaction to populate higher angular momentum states. We discuss new transitions observed in 66Fe and odd-A neighbors, 67Co and 65Fe, and the interpretation of these level schemes in terms of the rotational model of the nucleus. |
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GA.00040: Abstract Withdrawn
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GA.00041: Beta-Decay of 29F: The Southern Shore of The Island of Inversion Jesse N Farr, James Christie, Isidora Fletcher, Donnie Hoskins, Philipp Wagenknecht, Zhengyu Xu, Miguel Madurga In nuclear physics, the island of inversion refers to exotic neutron-rich nuclei that do not follow a standard configuration in the nuclear shell model. To explore this region, the 29F experiment ran in October 2020 at NSCL in Michigan State University. This experiment studies an isotope of fluorine, 29F, in a fragmentation nuclear reaction by implanting it in a crystal detector to measure its decay. By analyzing the decay of this neutron-rich isotope, it will lead to a better understanding of its decay strength, ground state wave function, and the internal structure of 29F and other exotic nuclei near the island of inversion. The VANDLE array alongside a YSO scintillator and three Germanium clover detectors analyze the ions for each individual event to map the decay. The clovers are fitted with thin beta-veto (vetos) plastics in order to maximize efficiency; we determined 2 mm offered the best compromise between high beta response and small gamma background. In this presentation we will show the simulations and evaluation data used to define the beta gamma response. |
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GA.00042: Separating Signal from Noise for (d,n) Reactions using NEXT Destynne M Oliver, Kelly A Chipps, Michael Febbraro, Robert Grzywacz, Joseph Heideman, Laurence Heilbronn, Kate L Jones, Toby King, Noritake Kitamura, Jerome Mathew Kovoor, Miguel Madurga, Shree K Neupane, Steven D Pain, Alicia Palmisano, Mustafa M Rajabali, Karl Smith, Michael S Smith, Rebecca Toomey The (d,n) proton-transfer-reaction can be used with both stable and radioactive ion beams to inform on nuclear structure and nuclear astrophysics. The Neutron dEtector with multi neutron (Xn) Tracking (NEXT) is a high-efficiency neutron time-of-flight detector array with neutron-gamma discrimination. The Hybrid Array of Gamma Ray Detector (HAGRiD) modules were also used in this experiment to measure the gamma-ray energies. A recent commissioning run to measure the previously known 20Ne(d,n) reaction was performed in inverse kinematics at the National Superconducting Cyclotron Laboratory (NSCL) using the ReAccelerated (ReA6) facility that provided a stable 20Ne beam at 10 MeV/u. |
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GA.00043: Commissioning Process for the High Rigidity Spectrometer (HRS) George Sun, Matt Amthor The HRS plays a key role in the scientific program of the Facility for Rare Isotope Beams (FRIB). It focuses and separates the products of nuclear reactions and thus provides insight into the reaction mechanisms and the nuclear structures involved. Our goal is to design and simulate the calibration process of the HRS. The work will allow us to reliably correct errors between reality and prediction and avoid the undesired first-order optical properties. |
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GA.00044: Validation of ENDF Inelastic Gamma Production Cross Sections Using the Baghdad Atlas Stefanie B Senjaya Gamma production from inelastic neutron scattering is important for many reasons – neutron transport modeling, fast neutron production, the analysis of isotopic samples using active neutron interrogation, and the development of nuclear reaction and structure models. Despite its importance, resources for validating the inelastic scattering gamma production data stored in the Evaluated Nuclear Data File (ENDF) library are scarce, and more information is needed. The Baghdad Atlas is a collection of data originated from a measurement campaign conducted at the Baghdad Research Reactor and is one of the most comprehensive collection of data on this type of gamma production. It is thus one of the best data validation resources currently available on inelastic gamma production cross sections. Comparison between the Baghdad Atlas and ENDF, however, is difficult due to the way the gamma production data is stored in ENDF for many isotopes. The purpose of this work is to develop a method for the cross section reconstruction and to validate the inelastic scattering gamma production in the ENDF database using the Baghdad Atlas. The major steps of this research include parsing the ENDF files, constructing level scheme, performing cascade calculations, as well as estimating the contribution from the quasi-contribution. The research being done will allow for the comparison of the data from the Baghdad Atlas to the ENDF database, which may ultimately improve the accuracy of the library itself. |
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GA.00045: Abstract Withdrawn
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GA.00046: Isomeric States in Neutron-rich Isotopes near A~100 Jack R Newcomb, Neerajan Nepal, Alejandro Algora, Alfredo Estrade, Shunji Nishimura, Jorge Agramunt, Deuksoon Ahn, Carlo Bruno, Roger Caballero-Folch, Tom Davinson, Iris Dillmann, Alexandra Fijalkowska, Naoki Fukuda, Shintaro Go, Robert Grzywacz, Tadaaki Isobe, Shigeru Kubono, Jiajian Liu, Giuseppe Lorusso, Keishi Matsui, Anabel Morales, S.E.A. Orrigo, Vi H. Phong, Bertis C Rasco, Krzysztof Rykaczewski, Hiroyoshi Sakurai, Yohei Shimizu, Daniel W Stracener, Toshiyuki Sumikama, Hiroshi Suzuki, Jose L Tain, Hiroyuki Takeda, Ariel Tarifeno-Saldivia, Alvaro Tolosa-Delgado, Marzena Wolinska-Cinhocka, Jin Wu, Rin Yokoyama The search for previously unknown nuclear isomers, or excited energy states within nuclei, continues to be an exciting frontier of nuclear physics as particle acceleration capabilities improve and unstable isotopes become more accessible. Nuclear isomers are typically formed as a result of in-flight fission and fragmentation reactions, and can exhibit metastable half-lives of the order of microseconds or longer. In order to discover potential new isomeric states within neutron-rich nuclei, a Be target was bombarded with a 345 MeV/nucleon 238U beam at the RIBF facility at RIKEN in Japan. The resulting fission produced a collection of isotopes in the A~100 range, which were separated out and implanted in the silicon detectors within the BRIKEN setup. Finally, 2 germanium clover detectors measured γ counts to identify energy levels from the produced isotopes. Here, we report on the observation of previously known gamma-decaying isomers, and search for new isomeric states for isotopes in the region from 92Se to 108Y. |
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GA.00047: Search for New Isotope Production Pathways. Loida Rosado Del Rio, Andrew M Hutton Radioisotopes are utilized in nuclear medicine for diagnostic and therapeutic procedures. One notable therapeutic use is cancer therapy, for which new, more effective treatment options are always desired. In order to produce a certain daughter radioisotope, its mother isotope must be the irradiated target isotope. However, there are many possible decay chains that can lead to the production of each radioisotope. Therefore, there is a need for an efficient way to identify a suitable target isotope for the production of a specific daughter isotope that can be used for treatment. This project focuses on the creation of a python program that evaluates the daughters of every possible gamma-nucleus interaction for all stable or long-lived target isotopes. Comparing the cross-sections for each reaction at a desired energy, the program outputs a list of the potential daughter isotopes that are most likely to be generated. Running the program for all stable or very-long-lived isotopes from Li-06 to U-238 resulted in 257 daughter isotopes. Of these, 8 are described by the DOE as isotopes of medical interest; while 3 of these have significant cross sections: cerium-134, scandium-47, and antimony-119. By knowing the daughter production and decay chain for each stable isotope, it is possible to go from the desired radioisotope to the stable isotope that can be used as a target for its production. This project would facilitate the search for new pathways to creating useful isotopes for medical diagnoses and treatments. |
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GA.00048: Gallium-68 in Medical Diagnostics Brecca Bettcher Positron Emission Tomography (PET) scans generate images of the body making noninvasive diagnostics possible for thousands of cancer patients. To provide higher image quality that better establishes and locates malignancies, ensuring more accurate and precise diagnoses, scientists continually develop new radiotracers. Gallium-68-based radiotracers have demonstrated promising clinical applications, however, predicting successful implementation in clinical practice requires a cost-benefit comparison against existing radiotracers such as fluorine-18-based radiopharmaceuticals. This presentation examines the imaging advantages and cost-effectiveness of gallium-68-based radiotracers against other conventional radiotracers and imaging modalities to assess when gallium-68 PET diagnostics would be beneficial in clinical settings. |
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GA.00049: Investigating the Role of Fission and the r-process in Heavy Isotope Creation in Neutron Star Mergers Hannah M Bechtel, SHELLY R LESHER, Ani Aprahamian Gravitational waves and electromagnetic signatures observed in 2017 from a neutron star merger have raised several questions about the fission process. Although fission has been studied for over 80 years, we are realizing that there are still processes involved in it that we don't fully understand. This paper attempts to review the role of the r-process (rapid neutron capture process) and fission in relation to heavy isotope creation. It is possible that data from the atomic bomb tests done in the 1950's and 60's could reveal information about the r-process because of the high neutron density from the atomic explosions that allowed for the creation of neutron-rich nuclei. Examining this data could lead to a better understanding of the observed neutron star merger. As such, more work is needed and it is the hope that looking for solutions at Los Alamos will lead to an answer. |
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GA.00050: PFAS Concentrations Using Quantitative PIGE Colin Langton, Scott M LaBrake, Katie R Sonntag
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GA.00051: Optimization of the Normalizing Flow Machine Learning Method for Microscopic Calculations of the Nuclear Equation of State Albany Blackburn, Pengsheng Wen, Jeremy W Holt Analyzing neutron stars, neutron star mergers, and core-collapse supernovae using a microscopic description of the nuclear equation of state offers many advantages over the dominant mean-field theory models, such as maintained connections to fundamental nuclear many-body forces, improved descriptions of thermodynamic quantities, and the ability to better track systematic uncertainty. However, introducing the higher-order, many-body corrections needed for such a microscopic description requires the evaluation of complicated, multi-dimensional integrals. We employ neural networks to learn and compute these integrals, using normalizing flows alongside Monte Carlo importance sampling. Using this framework, we investigate the effects of different pseudo-random number generators versus low discrepancy sequences and loss functions in the convergence of the normalizing flow model. Quasi-Monte Carlo (QMC) sampling methods studied include those based on the Halton sequence, the Korobov set, Lattice points, and the Sobol sequence. Models were compared directly against one another throughout training and evaluation for a variety of importance samplings methods and loss function implementations. We identify the optimal choices for the sampling methods and loss functions in evaluating perturbation theory contributions to the hot and dense matter equation of state. |
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GA.00052: Measurement of Neutron-Induced Fission Product Yields in 238U and 235U at Energies Below 4 MeV Molly C DeLuca, Sean W Finch, Calvin R Howell, FNU Krishichayan, Werner Tornow, Jack A Silano, Mark A Stoyer, Anton P Tonchev, Matthew E Gooden, Jerry B Wilhelmy When a heavy nucleus undergoes fission, it splits into two lighter fission products. Fission product yields (FPY) refer to the quantity of a particular fission product produced per fission. As a quantifiable feature of the fission process, FPY measurements provide insight into the mechanics underlying fission and hold significant implications for the fields of nuclear forensics, stockpile maintenance, and nuclear energy. While it is known that FPY vary with excitation energy, there is a lack of accurate data on the energy dependence of FPY, particularly at low energies. This study continues a LANL-LLNL-TUNL collaboration which was formed in order to collect accurate data on the energy dependence of neutron-induced FPY at energies below 14 MeV. Uranium targets were activated with a mono-energetic neutron beam; the target was held between two reference foils of the same isotopic composition in a dual fission chamber (DFC) in order to accurately measure total fissions. Following irradiation, the activated targets were γ ray counted with HPGe detectors. The resulting spectra were used to identify fission products by their characteristic γ rays and decay curves; FPY were quantified by comparing γ ray counts in the detector to total fission counts in the DFC. FPY in 238U and 235U were measured at 2.0, 2.4, and 3.6 MeV. |
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GA.00053: Characterization of Sodium Iodide Scintillation Detectors on the Basis of Positional Response Isabel Martinez, Grigory V Rogachev, Antti Saastamoinen
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GA.00054: Investigations of Diamond Detectors for Particle Identification Sophia Nowak, Brian T Roeder With advancements to the chemical vapor deposition (CVD) technique, manufacturers are now able to produce single crystal diamonds with lower impurities than in the past. The diamonds made using CVD have been implemented as charged-particle detectors and have been shown to have good energy resolution, fast response time, and higher radiation hardness than silicon detectors. Because of these characteristics, diamond detectors may be used for accurate particle identification, with the potential to perform well in high energy experiments. Work presented includes data from both a diamond telescope detector and silicon telescope detector. The detectors were placed at the end of the Momentum Achromat Recoil Spectrometer (MARS) beamline at the Texas A\&M Cyclotron Institute. Using a 35 Mev/u 78Kr beam produced by the K500 superconducting cyclotron on Be and Ni targets, a direct comparison of the data from the silicon detector and the diamond detector was performed. While particle identification was possible using a ∆E - E diamond telescope, it was also observed that diamond detectors suffer from saturation and significant pulse height defects. |
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GA.00055: Manufacturing and Testing Metamaterial Arrays Aubrey Parks, Ethan Henderson, Carl A Gagliardi Electron Cyclotron Resonance (ECR) ion sources generate the ions accelerated at Texas A&M's Cyclotron Institute. However, while scientists know how to use ECR ion source to create specific ions, the properties of the plasma within the source are relatively unknown. The ultimate goal of this project is to install a microwave camera into the ECR ion source to gain a temperature gradient over the plasma. The results from this project will provide knowledge about the fundamental properties of the ECR plasma, which will give enhanced knowledge of the ECR ion source, creating stronger beams for the cyclotron. My contribution to this project included developing code for the microwave camera's metamaterial array control system, assisting in designing manufacturing and testing procedures for the metamaterial arrays, and making reflectivity measurements as part of the preliminary validation of the metamaterial design. An update on the progression of the creation of the system will be shown. |
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GA.00056: The Identification of Contaminants by Time Evolution in 99Mo Gamma Decay Spectrum Nolan T Tenpas In efforts to differentiate emitted γ-rays with similar emission energies in the analyze of the γ-decay spectra from the 99Mo production, an automated program was created. The 99Mo production is part of the novel approach to producing medical isotopes, using inverse kinematics, successfully implemented at the Cyclotron Institute, Texas A&M University[1-2]. The 99Mo was produced using an accelerated 100Mo beam impinging on a 4He gas cell-target. An 27Al catcher foil, placed after the gas cell, was used to collect the 99Mo nuclei, as well as other coproduced nuclides. After irradiation, the γ decays spectra of the foil was measured using HPGe detectors. The photopeak associated with the highest γ-ray intensity of 99Mo, located at Eγ = 140.5 keV, was not resolved, due to contributions of γ decays from multiple nuclides. The total activity at Eγ = 140.5 keV can be described as a combination of 99Mo (t1/2 = 65.94 h; Iγ = 89.43%), 99mTc (t1/2 = 6.01 h; Iγ = 89.0%), and 90Nb (t1/2 = 14.60 h; Iγ = 66.8%). The new analysis program was used to plot the activities as a function of time, for the 140.5 keV photopeak while considering the activities obtained from other photopeaks associated with 99Mo (Eγ = 181 keV) and 90Nb (Eγ = 1129 keV). Using the known decay constants of each produced nuclide, the contribution of each nuclide was determined. The activity as a function of time was fitted and contributions from 99mTc, 99Mo, and 90Nb were determined. |
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GA.00057: Transport Efficiency of the St. Benedict RF Carpet Olivia Bruce, Maxime Brodeur, Marc A Yeck, Patrick D O'Malley The Superallowed Transition BEta NEutrino Decay Ion Coincidence Trap (St. Benedict), currently under construction at the University of Notre Dame Nuclear Science Laboratory (NSL) will be used to measure the mixing ratio of mirror nuclides to test the Standard Model. The St. Benedict will include four major components: a gas catcher, a differentially-pumped extraction system, a radio-frequency quadrupole (RFQ) cooler and buncher, and a Paul trap. The differentially-pumped extraction system will include two chambers pumped separately. Assuming the gas catcher is operated at 100 mbar, the first chamber will be pumped down to about 3 mbar, while the second chamber will have a pressure of about 10-3 mbar. The first chamber will use a radio-frequency carpet for the ion transport while the second chamber will use a RFQ ion guide. To test the transport of ions on the RF carpet several tests were first done in a chamber with static gas, reaching transport efficiency above 90%. Then we installed the carpet in the differentially-pumped extraction system chamber and tested ion transport with gas flow. We also studied RF carpet transport efficiency for different pressures. |
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GA.00058: Optimizing Machine Learning Code to Classify Neutron Resonances Mary Fucci, Gustavo P Nobre Understanding the nuclear formation and decay processes of elements is crucial to unravelling the mysteries of our universe. |
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GA.00059: Single-particle and collective excitations in 66Zn Matteo R Fulghieri, Akaa D Ayangeakaa, Robert V Janssens, Shaofei Zhu Medium and high-spin states in 66Zn were investigated by means of the complex multinucleon transfer reaction 26Mg(48Ca, α4nγ) at beam energies of 275, 290 and 320 MeV. The experiment was performed in inverse kinematics at the ATLAS facility at Argonne National Laboratory using the Gammasphere spectrometer and the fragment mass analyzer (FMA). A high-spin, quasi-rotational-like band consisting of stretched-E2 transitions was observed in coincidence with the known low-spin structure of mostly single-particle character. However, due to fragmentation, the two structures could thus far not be linked. A general discussion, complemented by theoretical calculations, of the observed structures will be presented within the context of shell structure evolution and collectivity in the A ∼ 60 mass region [1-3]. |
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