A Comprehensive Background Model and Search for Sub-GeV Dark Matter in LUX
by
48-224 - Madrone
SLAC
LUX (Large Underground Xenon) is a retired, liquid xenon, direct dark matter detection experiment that published its third and best limit on the spin-independent cross section for WIMP-nucleon scattering in the fall of 2016. Subsequently, the collaboration efforts have shifted to completing searches for new physics at energies above and below the standard WIMP-nucleon scattering range. In this expanded regime, accurate determination of the background rate from radiogenic sources is exceedingly important due to the complicated shape of the energy spectrum from these events. This talk presents the latest analyses of 𝛼, 𝛽, and 𝛾 backgrounds, and discusses the impact of these studies on the detector sensitivity to new, high and low energy physics searches.
There is particular emphasis on a technique that allows LUX to lower its energy threshold and enables searches for low-mass dark matter. While LUX’s standard WIMP-nucleon scattering search requires the presence of both a scintillation (S1) and ionization (S2) signal from every event, we are able to significantly lower the energy threshold by using only the latter. This technique lets us determine the energy of events, but does not allow for the reconstruction of their z-coordinate positioning. As a result, new events from regions at the top and bottom of the detector, which would normally be rejected, are introduced. This talk will discuss mitigation strategies for these background events and present the latest results from LUX’s ionization-only low-mass dark matter analysis.
Alden Fan / Christina Ignarra