Nuclear Physics Projects
1. High-precision Neutron-induced Cross-section Measurements on Iridium
Mentor: Alex Crowell
Student: Thomas Waterman
Studies of neutron-induced reactions are of considerable significance, both for their importance to fundamental research in nuclear physics and astrophysics and for practical applications in nuclear technology, medicine, and industry [Fessler, Nucl. Sci. Eng. 134, 171 (2000)]. One such practical application is the development of dosimetry materials, also referred to as radiochemistry diagnostics, which can be used to determine neutron fluence by measuring the transmutation of the initial isotopes into product isotopes in the neutron environment.
Iridium (Z = 77) is widely used in various medical and industrial applications, ranging from cancer treatment to activation detectors. The two isotopes of natural iridium constitute a well-known neutron fluence detector and have also been part of historical nuclear explosive device performance. The student on this project will be involved in cross-section measurements on iridium using the tandem accelerator to acquire neutron activation data, as well as analyzing data from previous measurements at TUNL.
2. High-precision Measurements of the Ratio of the Fission Cross Sections for 239Pu/235U
Mentor: Sean Finch
Student: Thomas Ordahl
The uranium and plutonium fission cross sections are standard reference cross sections and have been used to normalize hundreds of experimental data sets. The Fission TPC (time projection chamber) collaboration has recently published new data indicating small discrepancies from the presently adopted cross sections. Given the importance of these cross sections, we propose to measure the cross section ratios to the 1.5% uncertainty level. This measurement will not be as extensive as the Fission TPC project, but is a smaller, calibrated check on the Fission TPC results. The measurement involves two parts: (1) a measurement using a neutron beam and (2) characterization of the targets. For the first part, the student will participate in runs where uranium and plutonium targets will be installed in a fission chamber and irradiated using the mono-energetic neutron beams produced by the TUNL tandem accelerator. For the second part, the student will use an alpha spectrometer, based on a silicon detector, to measure and characterize the targets to the high level of precision required.
3. A GPU-based Data Acquisition System for Compton Experiments at HIγS
Mentor: Danula Godagama
Student: Jordan McPherson
The Compton@HIγS experiment studies the neutron's internal structure using Compton scattering on light nuclear targets. To achieve the energy resolution needed, this experimental campaign uses two large-volume NaI detectors along with an array of medium-sized NaI detectors. These large detectors have around 30 signal channels each while each medium-sized detector has 15 signal channels. The collaboration has invested in significant resources to develop a data acquisition system (DAQ) to digitize and preserve the complete waveforms from more than 80 signal channels used in the experimental setup. In preserving the entire waveform of the signals from each detector, a single experiment usually produces approximately 2 TBs of data per day. Processing such large data sets is computationally demanding.
The main goal of this project is to utilize the power of modern GPU programming techniques to parallelize a portion of the signal processing and thereby increase the data flow speed.
The student will work on developing a waveform processing program using the CUDA parallel computing platform by Nvidia Corporation. This program will be integrated into the existing data acquisition system. Additionally, the student will collaborate on the implementation of new hardware necessary for this upgrade and assist in the commissioning of the DAQ for the upcoming 3He Compton scattering experiments.
4. Construction and Commissioning of a Cryogenic Silicon Particle Detector Test Chamber
Mentor: Forrest Friesen
Student: Phoebe Alva Rosa
The proposed deuteron charge radius experiment (DRAD) at Jefferson Lab will involve adapting the experimental setup from the proton charge radius (PRAD) experiment, with the addition of a position-sensitive deuteron recoil detector placed inside the cryogenic deuterium gas target. This hypothetical recoil detector is currently being designed, and will need to be developed and tested in conditions comparable to those in the main experiment. This project will focus on setting up a large target chamber with a cryo-cooler and using it to characterize silicon charged particle detectors at low temperatures in partial vacuum. Initial tests will use alpha particles from a 241Am source, but if progress permits, we will also make use of the tandem accelerator to produce a deuteron beam. The work will be very hands-on at all stages and involve a variety of technologies and techniques. Experience with any of the following is helpful but not required: vacuum systems, cryogenics, fabrication / CAD software, electronics, and programming.
5. Beam Induced Background Studies at LENA
Mentor: Caleb Marshall
Student: Lilla Carroll
The 12C(α,γ)16O reaction is one of the most import nuclear reactions in all of astrophysics. It plays a key role in our theories of stellar evolution and nucleosynthesis; however, it is currently impossible to measure it directly in a laboratory at the low energies relevant to astrophysics. Pushing to lower and lower energies has been an ongoing and worldwide effort for the last 50+ years. LENA II located at TUNL consists of a pair of high intensity accelerators capable of delivering mA beams with acceleration voltages up to 2 MV, making it a facility well suited for measurements of the vanishingly small 12C(α,γ)16O nuclear cross section. An REU student would be on the leading edge of these efforts with their project to diagnose beam-induced backgrounds and explore active shielding methods to suppress these signals. The project would emphasize laboratory work: target fabrication, gamma ray spectroscopy, and data taking with the LENA Singletron accelerator.
6. Neutrino Physics Studies
Mentor: Kate Scholberg
Student: Celeste Guerrero
(The REU student assigned will select one of the two projects to work on.)
- Simulation and data analysis for COHERENT
Coherent neutral current neutrino-nucleus elastic scattering (CEvNS) is a process in which a neutrino interacts with a nucleus, giving it a recoil kick. Although the probability for such a process to occur is relatively high, the process is difficult to detect because typical nuclear recoil energies are very small. Because the rate of the process can be quite precisely predicted, a deviation of measurement from prediction could indicate new physics beyond the Standard Model. The COHERENT experiment has made the first measurements of this process at the Spallation Neutron Source at Oak Ridge National Laboratory in Tennessee, and is currently pursuing further
measurements. There are additional interesting possibilities for studies of inelastic interactions of neutrinos with nuclei. This project may include design, simulation, background evaluation, and data analysis work. The student will gain experience with a variety of simulation and data analysis software tools. Programming experience will be very useful but is not required.
- Physics studies for a large liquid argon detector
A 40-kton underground liquid argon detector is being designed for DUNE, the Deep Underground Neutrino Experiment. Physics capabilities include neutrino oscillations with a long-baseline beam, solar and atmospheric neutrinos, and supernova neutrinos. This project will involve participation in simulation and physics sensitivity studies for this detector. The student will gain experience with a variety of simulation and data analysis software tools. Programming experience will be useful but is not required.
7. Improving Reconstruction for Low Momentum Pions at CLAS12
Mentor: Anselm Vossen
Student: Keegan Mencke
The CLAS12 spectrometer is used at Jefferson Laboratory to study the quark-gluon structure of the proton. One issue with using the spectrometer is that low momentum pions, for example from lambda decays, show a degradation of their resolution with the current reconstruction software due to the non-trivial fringe magnetic fields. The purpose of this project is to explore if Machine Learning (ML) or Bayesian methods can improve the resolution of the pion reconstruction.
The student on this project should have some programming experience and ideally some previous exposure to ML/AI.
8. Affinity Estimation at the EIC
Mentor: Anselm Vossen
Student: Penn Smith
In order to extract the quark distributions inside the proton from Semi-Inclusive Deep-Inelastic Scattering (SIDIS) events, one has to be able to factorize the cross-section into Parton distribution functions, a hard scattering part and the fragmentation functions. Depending on the kinematics of the events, corrections to the factorized cross-sections are not negligible.
In this project, the kinematics of SIDIS events at the Electron-Ion Collider (EIC) will be studied in simulation to determine the ‘affinity’ quantity, which is related to the applicability of factorization theorems. Programming experience and experience with MC simulations in NP or HEP will be helpful.
9. Cosmic Study for the Elastic Compton Scattering at HIγS
Mentor: Jingyi Zhou
Student: Sarah Estupinan Jimenez
The COMPTON@HIGS collaboration is working to understand how nucleons respond to external electromagnetic fields due to their internal structure and the nature of the nuclear strong force. This is done by inducing Compton scattering between gamma rays with energies in the range of 60-100 MeV and different types of light nuclei. Currently, a liquid 3He target is being used to study the neutron, and the experiment is running at the High Intensity Gamma-ray Source Facility. To conduct such measurements successfully, background suppression, especially from cosmic rays, is important. In this project, a new veto paddle will be developed to further reduce background events in data collected by the five NaI detectors (HINDAS). The typical cosmic rate in a HINDA detector is around 72,000 counts per hour. With a series of preexisting methods, we could reduce the rate to nearly 50 counts per hour. With the paddles, we hope to further reduce the background by at least a factor of two.
High-Energy Physics Projects
1. Searching for Dark Matter at the LHC Using Graph Computing Algorithm
Mentor: Ashutosh Kotwal
Student: Kwame Bennett
A major instrumentation upgrade is planned for the LHC at CERN. The instrumentation upgrade provides the opportunity to use an algorithm that can be programmed directly onto silicon-based integrated circuits using field-programmable gate array technology. This algorithm uses graph computing to detect charged particles that decay invisibly with one of the decay products possibly being dark matter. The algorithm requires the hits recorded by the detectors to be partitioned in specific ways. In this project, the student will evaluate new methods of partitioning the data.
2. Exploring Spin Interference in the Parton Shower
Mentor: Ayana Arce
Student: Matthew Gratrix
Energetic partons (quarks and gluons) appear as jets in LHC collisions. The production of jets begins with a parton shower, a process that ends up hiding most of the interesting information about the original quarks and gluons. Multi-point energy-energy correlators (EEC) are a set of jet observables that can reveal quantum interference in jets. This project will use simulated data to design an ATLAS measurement of EEC as direct probes of the quantum aspects of jet substructure, focusing on spin and color interference effects.
3. Measuring Entanglement of Orbital and Spin Angular Momenta in Top Quark Decays
Mentors: Mark Kruse, Ayana Arce
Students: Khushi Vandra and Grace Miller
Elementary particles like top quarks produced by proton collisions at the LHC provide a laboratory for testing novel aspects of quantum entanglement, such as the way the entanglement of an unstable state is transferred onto its decay products. The goal of this project, a first step towards a first complete description of the quantum state of top quark decays in LHC collisions, is to determine some parts of the spin and angular momentum density matrix describing top decays from simulated LHC data.