Undergraduate Research at Jefferson Lab

Construction and Testing of Data Acquisition Components for the Hall A Compton Polarimeter

Student: Joshua Hill

School: The College of William and Mary

Mentored By: Robert Michaels

Nuclear physics experiments require accurate knowledge of the spin polarization of the electron beam delivered to the experimental halls. Hall A is upgrading its Compton polarimeter in support of the lab's 12 GeV beam energy upgrade. This project centered around the data acquisition (DAQ) system for the scattered-photon detection component of the polarimeter. The goal was to test whether the DAQ software and hardware are capable of capturing, recording, and processing electron helicity-dependent scattering rate asymmetry data at high rates, while maintaining appropriate accuracy. We created the necessary circuits, and are able to reliably extract asymmetries of between 0.5% and 11.5% to 0.2%. We did this in a deadtime-free regime at rates between 100 KHz and 350 KHz. We currently are unable to measure the system deadtime after it becomes manifest at about 350 KHz . These tests support the use of a scaled version of this configuration.