Many different types of astronomical evidence suggest that most of the mass in the universe is attributable to a nonluminous matter, called dark matter by physicists. Dark matter is believed to be one or more new elementary particles with currently unknown properties. So far, the prevailing method for attempting to discern the properties of the new particle(s) is to observe a direct collision between dark matter and standard model particles. SuperCDMS is a direct detection experiment conducted underground that measures ionization and phonon energy in cryogenic germanium crystal detectors. While taking data in the CDMSlite configuration it can amplify the ionization signal, dramatically lowering the threshold for a detectable amount of energy deposited in the detector via a collision with a hypothetical dark matter particle. Previous analysis of data taken in the CDMSlite mode examining the elastic scattering limit disregarded any energy loss due to the dark matter passing through the earth and atmosphere to reach the detector. The practical effect of this energy loss is that any dark matter particles which have very high interaction cross sections with normal matter (∼ 10−30cm2) will have lost too much of their energy to be detectable by the experiment once they have reached it. This work will describe a method to account for this effect and present a re-analysis of the CDMSlite run 3 data, resulting in an adjusted sensitivity band, rather v than just a lower limit. The lower limit of the new band is consistent with the previously published lower limit obtained without incorporation of the overburden. The upper limit is consistent with the previous limits from other experiments, with an upper limit on the cross section of 10−31 cm2 for a 1.5 GeV WIMP.
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Litke, Michael, "Application of Overburden Effects to the Elastic Scattering Limit for CDMSlite Run 3" (2023). Physics Theses and Dissertations. 17.