Finding an Alpha Rejection Factor in 40 torr CS2

Abstract

For a variety of reasons, it is presumed that Dark Matter constitutes up to 90% of the mass in the universe. We believe that Weakly Interacting Massive Particles (WIMPs) are a promising candidate for Dark Matter. Positive identification of WIMPs has yet to occur; the Dark Matter project at Occidental is hoping to use a DRIFT (Directional Recoil Identification From Tracks) chamber to observe WIMPs. Because the expected imbalance between background and WIMP event rates in the DRIFT chamber will be in favor of the background, it is crucial to the success of this detector for it to be able to discriminate between the two types of events. The DRIFT chamber has the capability to measure the total amount of ionization per event, and the x- and z-components of the ionization track left by the ionizing particle. The x- and z-components are combined into a variable, R2, which represents the length of the projection of the ionization track onto the x-z plane. Mathematically, R2 is :