Measuring Backgrounds from ⁸⁵Kr and ²¹ºBi to Improve Sensitivity of Dark Matter Detectors
Abstract
Understanding background events in a low-energy search for the WIMP dark
matter candidate is critical to enable a viable search as these events must be reduced
to avoid overwhelming the rare dark matter signal. The βˉ decay spectra from ²¹ºBi
and from ⁸⁵Kr have energies in the dark matter search region of ≤100 keV. This work
identifies 38.0 ± 6.2 ⁸⁵Kr events via its rare β-γ coincidence decay path in the LUX
detector's 332-day dark matter search. Furthermore, the activity of ²¹ºBi which can
be tolerated in the detector before it is discernible in the low-energy region of the
radioactive background spectrum is determined for a variety of radial cuts to study
how the mobile ²¹ºBi infiltrates a dark matter detector's fiducial volume. This sets
a limit on acceptable ²¹ºBi activities which will help future low-energy experiments
determine the steps they must take to build competitively sensitive detectors.
Citation
Mannino, Rachel Louise (2017). Measuring Backgrounds from ⁸⁵Kr and ²¹ºBi to Improve Sensitivity of Dark Matter Detectors. Doctoral dissertation, Texas A & M University. Available electronically from https : / /hdl .handle .net /1969 .1 /165702.