Reduction of Alpha Particle Backgrounds

Author: Connor Peterson, Department of Physics

Mentor: Dr. Richard Schnee, Department of Physics

A large emphasis of modern physics experiments is focused on finding dark matter. Dark matter is a form of matter that appears to be abundant throughout the universe, but whose direct detection remains elusive. Here in South Dakota we house the next generation of experiments to try to find this type of matter, LUX-ZEPLIN (LZ). To increase the sensitivity of LZ and future detectors, we must find ways to reduce interactions from other particles. Of particular note are alpha decays that occur naturally from the daughters of radon in the air. Continuing research suggests that removing the surface charge on samples reduces the number of radon daughters that land on the samples, leading to a quantifiable reduction in backgrounds from these alpha decays. By reducing the surface charge on a sample, we mitigate the effects of the radon daughters being attracted to the charged surface. Initial tests have demonstrated that using an ionizing fan can reduce the number of radon daughters depositing by an order of magnitude. MATLAB analysis code uses the time dependence of alpha decays to deduce the starting number of atoms on a sample, determining the effect of different factors on reducing the deposition of radon daughters and allowing more sensitive future dark matter searches.