Undergraduate Research at Jefferson Lab

Analyzation of the Handbag Mechanism through a Polarized Helium-3 Target

Student: Katelyn Thomas

School: Emory University

Mentored By: Arun Tadepalli

The goal of nuclear physics is to understand the structure and interactive mannerisms of atomic nuclei and their subatomic components. This project will focus on the behaviors of the quarks which constitute a neutron. To probe into this structure, we will utilize polarized helium-3 residing within two perpendicular pairs of Helmholtz coils which serve as a neutron target. In this experiment, an electron beam strikes the target to allow for the study of nucleon form factors. Previously, models of this experimental data were developed from similar studies whose best estimates were inaccurate by two orders of magnitude. Now, a new model called the handbag mechanism shows promise in accurately predicting the behavior of these form factors. With this development, our study works to calibrate our experimental system such that we can determine the validity of the handbag mechanism model by repeating experimental trials. To perform these calibrations, we first calculated the magnetic field of our experimental system. Using this, we calculated the current necessary to run through each coil pair provided some preliminary parameters from initial experimentation. Finally, we measured the offset angle of the electron beam to the first coil plane it intersects such that we could determine the polarization angle of the system. Provided these calculations, we will be able to calibrate our experimental system to determine if results align with the predictive handbag-model. If these experimental results agree with previous measurements, then this new model is confirmed to have significantly improved our ability to predict the observed differential cross sections for single pion photoproduction in the wide-angle regime. This result aids in a better understanding subatomic behavior.