Speaker
Mr
Dylan Temples
(Northwestern University)
Description
Dark matter searches using dual-phase xenon time projection chambers (LXe-TPC) rely on the discrimination between electronic recoils (background) and nuclear recoils (signal) based on the ratio of ionization electrons to scintillation photons produced by the interaction in the liquid xenon. This discrimination is calibrated at low energies using tritium $\beta$-decays. However, neutrino and Compton scatters from inner-shell electrons of xenon atoms result in the emission of Auger electrons and x-rays in addition to the primary recoiling electron, and thus have a different event topology than $\beta$-decays and valence-shell electron recoils. Due to their low kinetic energy and large numbers, these secondary particles can deposit large amounts of energy within a small radius, which is uncharacteristic of valence electron recoils and is more akin to nuclear recoils. This effects the profile of the neutrino-electron scattering background in a way that is, so far, uncalibrated and unaccounted for in LXe-TPC dark matter searches, and presents the possibility of a false discovery claim. To investigate the significance of this effect, electrons capture decays of $^{127}$Xe are used to simulate the vacancies produced by inner-shell $e^-$-$\nu$ scatters in the Xenon Electron-recoil L-shell Discrimination Analyzer (XELDA) detector. The $^{127}$Xe source produces a high-purity sample of inner-shell vacancies accompanied by an Auger cascade that can easily be isolated from the prompt $\gamma$'s emitted in the decay. In this talk, I will present the results of a cross-calibration of the XELDA detector using both $^{127}$Xe EC-decays and $^{3}$H $\beta$-decays, and discuss the implications this result has on the rejection capability of neutrino-induced electron recoils in large-scale LXe-TPC dark matter searches, such as LUX-ZEPLIN.
Primary author
Mr
Dylan Temples
(Northwestern University)
Co-authors
Dr
Alissa Monte
(Fermilab)
Dr
C. Eric Dahl
(Northwestern University)
Dr
Daniel Baxter
(University of Chicago)
Mr
Jacob McLaughlin
(Northwestern University)
Mr
Jason Phelan
(Northwestern University)
Dr
W. Hugh Lippincott
(Fermilab)
