Undergraduate Research at Jefferson Lab

Designing a Wien Filter Model with General Particle Tracer

Student: John Mitchell

School: College of William and Mary

Mentored By: Alicia Hofler

The Continuous Electron Beam Accelerator Facility (CEBAF) injector employs a beamline component called a Wien filter which is typically used to select charged particles of a certain velocity. The Wien filter is also used to rotate the polarization of a beam, setting the spin of particles as they pass through. To ensure the Wien filter is functioning properly, Beam Position Monitors (BPMs) are placed before and after the filter to measure changes in the beam orbit caused by the filter. For the purpose of diagnostics, magnetic dipoles called correctors are placed at various positions upstream of the filter. The field strengths of these dipoles are varied to bend or "kick" the beam, affecting particle trajectories through the Wien. The focus of this project was to create a simulation of the Wien filter using General Particle Tracer (GPT). The results from these simulations were vetted against machine data to analyze the accuracy of the Wien model. Due to the close agreement between simulation and experiment, the data suggest that the Wien filter model is accurate.