2022 TUNL REU Projects

Nuclear Physics Projects

1. High-precision Neutron-induced Cross-section Measurements on Iridium

Advisor: Alex Crowell

Student: Elijah Scurlock

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 all aspects of neutron-induced cross-section measurements on iridium using the tandem accelerator and RABITTS rapid transfer system, including setup, data-taking, and analysis.

2. Characterization of Uranium Foils for High-precision Measurements of Fission Cross-section Ratios

Advisor: Sean Finch

Student: Caleb Miller

The uranium and plutonium fission cross sections are standard reference cross sections 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. To do this, uranium and plutonium targets will be installed in a fission chamber and irradiated using the mono-energetic neutron beam produced by the TUNL tandem accelerator. To achieve a low level of uncertainty, the student will use an alpha spectrometer, based on a silicon detector, to thoroughly characterize the targets. The student will modify the alpha spectrometer such that they can perform radial scans of the uranium targets, image the alpha activity, and quantify the target uniformity.

3. 42Ar Background for LEGEND-1000

Advisors: Phil Barbeau and Matt Green

Student: Jackie Baeza-Rubio

The LEGEND-1000 experiment is a ton-scale search for neutrinoless double beta decay that will consist of Germanium semiconductor detectors emerged in a liquid Argon cryogen. A particularly pernicious background comes from the beta decay of 42K, a daughter of 42Ar, which is produced in cosmic ray collisions in the upper atmosphere. LEGEND-1000 seeks to understand the flow patterns of 42Ar in the liquid, their collection on the charged surfaces of the detectors, and the resulting background from the beta decay after it penetrates the dead layer of the germanium crystal. This project will produce a sample of 42Ar at the tandem accelerator in order to study its behavior, using the drop-off reaction of (4He, 40Ar)42Ar.


4. Pb-Glass Detector for Neutrino Charged Current Measurements

Advisors: Phil Barbeau and Diane Markoff

Student: William Henshon

The COHERENT Collaboration has reported anomalously small rates for the neutrino charged-current interaction on Pb. This could have startling impacts for the COHERENT experiment, for neutrinoless double beta decay experiments, SuperNova detectors, and may play a role in R-process nucleosynthesis. We are in possession of 3 tons of Pb-glass, which may be able to resolve this tension. This project will produce preliminary detectors to test the viability of the full-scale 3T deployment.

5. Beyond the Standard Model Searches in LEGEND

Advisors: Phil Barbeau and Matt Green

Student: Lauren Dressler

The LEGEND-200 experiment has recently collected 1 month of data with 18 detectors. A series of quality checks need to be performed on this data. Each detector must also be calibrated for energy scale. Once achieved, a number of searches for Physics Beyond the Standard Model will thus be possible, including, for example, Fermionic Dark Matter.

6. Simulation studies of the HALO detector

Advisor: Kate Scholberg

Student: Olivia Bitcon

The HALO (Helium and Lead Observatory) detector is under construction at SNOlab in Sudbury, Canada. This detector, composed of lead and He-3 neutron detectors, will have a unique sensitivity to the burst of neutrinos from a nearby supernova. This project will involve participation in simulation and physics sensitivity studies for HALO. 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. Flavor Correlations of Leading Hadrons at Belle II

Advisor: Anselm Vossen

Student: Nathaniel Kirby

The dynamics of hadronization, the formation of colorless particles from quarks, is governed by the strong force. However, it is inaccessible with perturbative calculations and our insight comes mainly from the parametrization of measurements and models. Recently, correlation measurements between leading hadrons were suggested to test model predictions for hadronization. The electron-positron annihilation process as measured by the Belle II experiment is uniquely suited for these measurements, because, compared to nucleon scattering experiments, it is independent of the nucleon structure.

In this project, the student will be introduced to the Belle II analysis software with the goal to explore leading hadron correlations.

8. Evaluating Data from First Experiments with the Clover Array at HIγS

Advisors: Daniel Ayangeakaa and Udo Friman-Gayer

Student: Arlee Shelby

Nuclear structure research with photon beams requires measurements of gamma rays using sophisticated detection systems. At HIγS, the newly developed Clover Array consists of an assembly of high-purity germanium (HPGe) and cerium bromide (CeBr3) detectors. The first campaign of measurements with the Clover Array has recently been completed. It combined measurements proposed by TUNL scientists with other projects from outside users. At this point, the analysis effort focuses on understanding the intrinsic capabilities of the detection system from a number of measurements. The student will participate in this analysis effort. In particular, the focus will be on a data set from a nuclear resonance fluorescence measurement for the 197Au nucleus. Furthermore, delivery of a new detector is anticipated and the student will take part in its testing and full characterization. The student will also be encouraged to participate in weekly group discussions about progress in the analysis efforts and preparations for future experiments.


High-Energy Physics Research Projects

1. Searching for New Physics at ATLAS in Four-Tops Events

Advisor: Mark Kruse

Student: Katelyn Espe

The ATLAS Collaboration at CERN seeks to find New Physics Beyond the Standard Model, including a search for the Z’ boson in four-tops events. An extension of the current Z' boson search will be conducted by considering same-sign dilepton (electron or muon) channels. We propose to sort the detectable decay particles based on their kinematic properties. Using Monte Carlo simulated data for the same-sign dilepton events, the kinematic properties of truth-level particles will be correlated to create a method for grouping and classifying decay products.

2. Fast Pixel Tracking Metastable Particles with ATLAS-ITk

Advisor: Ashutosh Kotwal

Student: Andrew McEntaggart

Dark matter models are some of the most currently well-motivated and actively-pursued extensions to the Standard Model. Some theoretical models predict that the Large Hadron Collider is capable of producing dark matter candidates via decay from short-lived metastable charged particles. These particles would decay invisibly before reaching the outer sensors and thus escape detection.

In this project, we will investigate a proposed upgrade to detect short-lived charged particles produced at the Large Hadron Collider using the ATLAS Inner Tracker. We will study an algorithm to reconstruct the trajectories of these particles in detail and estimate the efficiency of a physical implementation.

3. Validation of ATLAS Jet Trigger Efficiencies for Run III

Advisor: Ayana Arce

Student: Andrea Munroe

The Large Hadron Collider (LHC) at CERN will soon begin Run III of proton-proton collisions at 13.6 TeV to produce novel subatomic particles. The ATLAS experiment will start taking data with hardware and software updated during the long shutdown. The purpose of this project is to validate the efficiency and performance of triggers for jets so that analysts can separate new physics from artifacts of a new data-taking methodology.  Trigger efficiencies for hardware-based Level 1 (L1) jet triggers will be generated using the ATLAS analysis packages. Operation of probe triggers will be compared to the output of known reference triggers.

4. Simulations for a Dark QCD Search

Advisor: Ayana Arce

Student: Ronald Vaughn II

Dark matter makes up about 27% of mass and energy in the known universe, yet there is still little known about the constitution and characterization of it. This problem is only compounded by the fact that dark matter lacks significant non-gravity interactions with Standard Model (SM) particles, making it almost impossible to directly detect. To narrow down the possibilities of what dark matter could be, we will set up a method for the future testing of dark matter models involving a self-interacting strong force. Such models have been named "dark QCD-like" after the study of the strong force, Quantum Chromodynamics (QCD). Using information from a number of articles, we will attempt to choose sensible parameters for our simulations. Using these simulations, we hope to determine how dark jets could decay into SM jets with unique characteristics that can be detected.