Undergraduate Research at Jefferson Lab

Computation of Bremsstrahlung Radiation and Ionization Phenomenon in the Linear Accelerator Section of CEBAF

Student: Mason Stoecker

School: Virginia Polytechnic Institute and State University

Mentored By: Matt Poelker

Bremsstrahlung is a process that will occur as the electron beam experiences deceleration. This work focuses on bremsstrahlung in the straight section of CEBAF called the Linear Accelerator (LINAC) where the beam collides with the residual gas present. If the beam encounters a gaseous species, the resulting ionization can cause problems for the vacuum stability in the form of ion trapping, beam neutralization, and bremsstrahlung. The focus of this project was to evaluate the magnitude of gas-bremsstrahlung at CEBAF and ionization increase energy spread in the electron beam, to determine if steps should be taken to minimize it. It was shown that the water vapor in the warm girder regions is most problematic, compared to the dominant gas species H₂ inside the cryomodules. Furthermore, gas ionization can lead to significant enhancement of gas-bremsstrahlung because ions can be attracted and trapped within the electron beam.