Point by point gain calibration of the Dark Matter Time Projection Chamber

Abstract

Since 1975 a growing body of astronomical evidence has given increasing credibility to the existence of dark matter. Once a simple proposition by Fritz Zwicky to explain discrepancies in the virial motion of galaxy clusters, dark matter can now explain galactic rotation curves, the hierarchical structure of the universe, and the gravitational lensing of the bullet cluster. Nonetheless, the exact particulate nature of dark matter remains a mystery. The Dark Matter Time Projection Chamber (DMTPC) is a directional detection experiment that will be able to measure the energy, length, and direction of nuclear recoil tracks induced by incoming weakly interacting massive particles (WIMPs). In this thesis I analyze nonuniformities in the CCD images used to record the nuclear recoils. I then identify the source of the nonuniformities and describe a method for calibrating the CCD images. The method improves the energy resolution by decreasing the uncertainty by a factor of 4 for the bottom time projection chamber (TPC) and a factor of 3 for the top TPC.