Session PA: Conference Experience for Undergraduates Poster Session V (4:40pm - 5:15pm)

Integral method for fitting nuclear decay chains

The conventional method for determining unknow half-lives of isotopes in data that have many decay chains is by fitting radioactive decay curves using the Bateman equations. The fit gets difficult in cases with very low statistics on the fast decaying components. To compensate for the low statistics, we propose a new method for fitting and extracting these half-lives. The new method consists of making an integral histogram of all the counts recorded from the radioactive isotope, then fitting the histogram with an integral of the Bateman method. In this work we show results from the new algorithm which was used to test the integral method. The validity of the integral method will also be disused. The result of the study will be shown I the presentation. This project was partially funded by the DOE grant number: DE-SC0016988   

A Study of Rare-Isotope Beams in Hadron Therapy

Hadron (e.g., proton, neutrons, heavy ions) beams in Radiotherapy have many biological and physical advantages in comparison to traditional beams such as electrons and photons. Within the past decades, many researchers have found promising results in the use of radioisotopes. For instance, one important advantage in hadron therapy is the possibility of accurately measuring delivered doses in real-time by monitoring the nuclear decay of the isotopes. These advantages have been at the forefront of cancer research, further expanding clinical modalities for cancer patients of various classifications. We first performed a comprehensive review of existing isotopes and techniques (imaging, dose measurements) used in clinical settings (from hadron therapy to brachytherapy) to identify the specificities of the use of radioisotopes. In our second study, we used the hadron therapy example of the Geant4 simulation toolkit to compare the dose distributions between stable and rare isotopes beams. We will present and discuss the results obtained from this study. In the near future, the impact on the DNA single and double strand breaks will be investigated. The Facility for Rare Isotope Beams (FRIB) under construction at Michigan State University will provide rare-isotope beams of high intensities. Ion sources are currently being used to deliver heavy ion rare-isotope beams to accelerator systems for nuclear physics. The current work will provide the foundation for the possible development of an ion source optimized for the delivery of rare isotope beams for hadron therapy and hence the treatment of various diseases.   

Lanthanide Database of Abundances Formed in Neutron Star Mergers

Kilonovae are optical transients associated with neutron star mergers (NSMs) and are powered by the radioactive decay of heavy elements created by the rapid neutron capture process(r-process). It is important to note that the blue and red emission components from the kilonovae, along with their timescales, are greatly dependent on the distribution of the lanthanides and their various charge states in the merger material. To analyze these mergers and their abundances, we study the event through an Atomic Physics lens. Numerous kilonovae modeling groups employ unique atomic structure codes, often resulting in diverging results. To assist in benchmarking these models and codes, we study how varying atomic data inputs, such as atomic energy level information, affect the total abundance of these unique elements, which in turn affects opacity and light curves. Utilizing elemental abundances calculated by Skynet, a nuclear reaction network code, we uncover how distinct isotopes evolve over time due to variables such as temperature and electron fraction. We then use these calculated elemental abundances, the Saha Equation, and NIST ionization data to predict the ionization state populations of lanthanides on timescales similar to the expected time of the kilonova peak as well as ranking certain ionization state abundances weighted by probable Ye values. We will report on our most recent results, and how a multi-element merger material should evolve over time. This work is supported by Michigan State University and the Joint Institute of Nuclear Astrophysics.~   

Machine learning for improved resolution and fast predictions in a parallel-plate avalanche counter with optical readout (O-PPAC)

The O-PPAC is a detector for tracking beam particles. It detects electroluminescence produced by the beam ionizing the detector gas. This work provides a method for faster, more accurate position measurements from the O-PPAC. The traditional method applies a truncated Gaussian fit, where the position of the particle event is localized by the event's centroid, as recorded by the collimated photo-sensors (e.g. SiPMs) lining the inner four walls of the O-PPAC. We replace this fit with a fully connected neural network, and we train a model to apply X,Y localizations to simulated data with known locations, so the model correlates event data with location. The next step is to test how well the model generalizes to experimental data to make consistently accurate predictions. Preliminary results indicate that the neural network yields improved event resolution. We achieve a resolution of 0.034mm in the X dimension and 0.042mm in the Y dimension using the neural network model.   

Simulating Detector Efficiency in Hyperion and STARLiTeR

The study of $\gamma $-ray emission from excited nuclei plays a crucial role in nuclear physics by offering insight into the structure of nuclei and the formation of heavy elements in stars. To better understand the efficiency of $\gamma $-ray detectors, computer simulations can be built in Geant4 to model the interaction of $\gamma $-rays with the detector materials. Simulations like these allow researchers to quickly and easily determine the effects that changes in the detector setup have on the $\gamma $-ray spectrum recorded in experiments. This work aims to create a simulation to better understand and determine the efficiency of the $\gamma $-ray detectors in the Hyperion and STARLiTeR systems, which are detector arrays currently housed at Texas A{\&}M University used in the study of astrophysical nuclear processes. The simulation is constructed to most accurately reproduce data taken in the STARLiTeR system for radioactive $^{\mathrm{137}}$Cs and $^{\mathrm{60}}$Co calibration sources and is used to calculate an efficiency function for the detector as a function of $\gamma $-ray energy.   

A Monte Carlo Investigation of Jet Shape Variables at RHIC Energies

Relativistic heavy ion collisions result in the formation of the strongly cou- pled medium known as the quark-gluon plasma (QGP). Jets are a collection of high-momenta particles emitted by hard scattered quarks and gluons (also known as partons) in the early stages of the collision. Jets interact with the QGP as they traverse the medium in a phenomenon known as jet quenching. Observables such as jet mass, jet charge and jet shape, are used to study this phenomenon. In this study, we utilize proton-proton collision events simulated by Pythia Monte Carlo generators as a base study for future data analysis at RHIC energies. We explore the correlation between these jet shape observables for anti-kt jets with a resolution parameter of R=0.4.   

Simulating the beam dynamics of the SECAR Recoil Mass Separator using DYNAC

The reaction rate of $^{56}$Ni(n,p)$^{56}$Co serves a key role in the neutrino-p process which is theorized to contribute to the synthesis of the elements heavier than Fe (e.g. St, Y, and Zr) in Type II core-collapse supernova. To constrain the reaction rate, the cross section of the inverse reaction, $^{56}$Co(p, n)$^{56}$Ni, will be measured with the Separator for Capture Reactions (SECAR). By simulating the transport of the $^{56}$Co beam and the $^{56}$Ni reaction product we are able to optimize the beam optics before the actual experiment. A model of the recoil mass separator SECAR has been created using the multi-particle beam simulation code DYNAC. The model allows the user to adjust the beam settings as well as the electric and magnetic fields of the elements along the beam line. DYNAC also enables users to create plots of the beam at any point in the beam line. These tools allow the user to optimize the electric and magnetic fields for a beam and study the aspects of the beam without ever having to visit the SECAR facility. With this model, we have been able to accurately recreate the transport of various beams used in SECAR commissioning . We then used the model to simulate and optimize a $^{56}$Co beam that we will use in the $^{56}$Co(p, n)$^{56}$Ni experiment.   

Simulation of Spin-Dependent Di-Hadron Production for the EIC

Scattering accelerated electrons off protons and detecting the final state particles of the collisions allows us to study the internal structures of the nucleons. The Electron Ion Collider (EIC) is being designed for construction at Brookhaven National Laboratory (BNL) and a yellow report is currently being developed to outline the detector and collider parameters based on the requirements of the various physics channels . This project will contribute to the report by developing software to simulate specific aspects of di-hadron production in semi-inclusive deep inelastic scattering. In particular, we studied detector resolutions based on the true and detector smeared kinematics and implemented a weighting scheme to simulate polarization effects in the cross-section based on theoretical models. In addition to charged pions, we also studied pairs including neutral pions which were reconstructed from photon pairs. With these improvements, more accurate and comprehensive simulations can be used in the yellow report.   

Development of a multi-neutron filter for use in the study of dripline nuclei

The MoNA Collaboration has investigated several neutron-unbound nuclidesthat decay by the emission of multiple neutrons. In the large MoNA array, it is difficult to discriminate between multiple neutron events and single neutrons scattering multiple times, so that an effective multi-neutron filter is important. Previous ``causality cut'' gates have proven helpful in eliminating single neutron scatters, but have also filtered out many multi-neutron events in the process. We have developed a new filter based on gates in a 2-d spectrum of ``neutron space time interval'' (nsi) vs. neutron scattering angle, combined with multiple proton cross-talk scattering events (where charge-exchange protons trigger multiple detector bars), which has proven to be very effective in eliminating 1-n events while maintaining a majority of multiple neutron events. We have applied this filter to three different experimental data sets and compared with simulation. Overall, this new filter improves multi-neutron statistics significantly and shows promise for use in future analysis. Results will be presented. Work supported by NSF grant PHY-2012511   

Precision magnetic field characterization for a neutron electric dipole moment search

A non-zero neutron electric dipole moment (nEDM) violates CP-symmetry and is thus closely related to the Baryon Asymmetry in the Universe. It is the goal of the TUCAN collaboration to search for an nEDM with a sensitivity of 10^-27 ecm. This experiment is conducted using ultracold neutron (UCN) spectroscopy. A static magnetic holding field applied to UCN must be controlled to the order of pico Tesla with respect to its homogeneity to achieve this sensitivity objective. My studies focus on developing an optimal measurement routine for an offline magnetic field mapping device. We adapted a state-of-the-art harmonic polynomial magnetic field decomposition to gain improved insight into the role magnetic field inhomogeneities play for systematic uncertainties. This enables the collaboration to determine different components of the uncertainty budget of a future nEDM measurement. On this poster I present a summary of my simulation and analytical work towards specific systematic uncertainties on the path towards an improved nEDM search sensitivity.   

Reconstructing Cross Sections in the Enge Focal Plane

Particle transfer and elastic scattering cross sections can be used to probe single-particle excitations in nuclei. The Enge Split-pole Spectrograph at the Triangle Universities Nuclear Laboratory (TUNL), is focused on understanding excited states important for astrophysical reactions. Key information about these excited states are excitation energies, spin-parities, and spectroscopic factors, all of which are essential in determining the cross sections of interest. To extract spin-parities and spectroscopic factors, theoretical differential cross sections are typically fitted to experimental data collected at a range of angles. Here we present a new method to determine the cross section in finer detail. By using a wide spectrograph entrance aperture, a method was developed to reconstruct these cross sections on a fine scale by performing ray-tracing through the focal-plane detector of the Enge Split-pole Spectrograph. This is achieved by including two position-sensitive sections in the detector package. The method was tested with well-known cross sections. To investigate the effects of detector response on this ray-tracing procedure, the Geant4 Monte Carlo simulation toolkit was used. The results of this reconstruction are finer, more detailed cross section calculations.   

Supernova Neutrino Estimation for Present and Future Telescopic Survey

Most massive stars will end their life with a violent explosion known as a core collapse supernova. The majority of a core collapse supernova's energy comes from neutrinos. Neutrinos give substantial information about the physics of a supernova. At present, there have only been approximately 20 neutrinos detected from supernovae, which all originated from SN1987A. Currently, there are programs that are continually looking for supernovae, such as the All Sky Automated Survey for SuperNovae, and the Zwicky Transient Facility. Data from these on-going surveys was visualized to gauge the importance of several factors. This information was used to estimate the total number of neutrino events that could be detected at the Hyper-Kamiokande (Hyper-K) detector from an energy range of 16-30 MeV. New telescopes are being constructed, such as the Legacy Survey of Space and Time (LSST), that will detect supernovae from further distances, which will increase the number of neutrino events seen. Observation time since the explosion and distance of the supernovae are important factors when determining how many neutrino events can be observed. We have predicted the number of supernovae LSST will detect over a range of distances with the hopes of determining the best strategy to find neutrinos.   

The Moller Experiment

The Measurement of a Lepton -- Lepton Electroweak Reaction, or MOLLER, aims to examine the weak charge of the electron through the parity -- violating asymmetry in electron to electron scattering. This can be done at Jefferson Lab, using their particle accelerator to collide subatomic particles (via a liquid hydrogen target). The statistical findings of this asymmetry will provide a precise proportionality to the weak charge of an electron. The sensitivity exuded in this experiment is incredibly significant as we expect to optimize previous measurements of the electroweak mixing angle by a factor of 5. Currently, we work to improve the dimensions and structure of the pion detectors used in the apparatus. Each pion detector records hits that are statistically analyzed. The results are then examined through Python based code and used to improve the next set of simulations. Pion detector work progresses our understanding of how subatomic particle collisions tend to the electroweak mixing angle and are ultimately instrumental for the experiment.   

The CLAS12 Reconstruction Resolution

Jefferson Lab's CLAS12 detector studies nucleon structure by measuring recoil particles in electron scattering experiments. The event data is processed by the CLAS12 reconstruction software. This project aims to find the reconstruction software resolution at each subsystem of the CLAS12 Forward Detector. The analysis was done on events created with the CLAS12 simulation software, \textit{gemc}. It produces state vectors of particles at the interaction vertex and simulates the CLAS12 response. The reconstruction software is then used to extract the trajectories from simulated detector hits. Two vertex state vectors, one generated at the start of simulation and one reconstructed, are used as input for swimming through CLAS12- the equations of motion of the particles in the CLAS12 magnetic field are integrated. The particles are swum to the surfaces of each of the subsystems in the Forward Detector. The differences in endpoint positions and angles are plotted and fitted, with the standard deviation of the fit giving a measure of the reconstruction resolution. The resolutions have been obtained for different conditions and particle species. The results will be used in matching drift chamber trajectories to hits in other subsystems of the Forward Detector.