LUX Trigger Efficiency

TL;DR

This paper evaluates the trigger efficiency of the LUX dark matter detector, demonstrating high efficiency (>98%) at relevant energy thresholds and across the detector volume, ensuring reliable event selection for dark matter searches.

Contribution

It provides the first detailed measurement of the LUX trigger efficiency using calibration data, highlighting its high performance and stability across energies and detector volume.

Findings

Trigger efficiency exceeds 98% at 0.2 keV for ER and 1.3 keV for NR.

Efficiency remains between 99% and 100% throughout the fiducial volume.

High trigger efficiency supports robust dark matter search results.

Abstract

The Large Underground Xenon experiment (LUX) searches for dark matter using a dual-phase xenon detector. LUX uses a custom-developed trigger system for event selection. In this paper, the trigger efficiency, which is defined as the probability that an event of interest is selected for offline analysis, is studied using raw data obtained from both electron recoil (ER) and nuclear recoil (NR) calibrations. The measured efficiency exceeds 98\% at a pulse area of 90 detected photons, which is well below the WIMP analysis threshold on the S2 pulse area. The efficiency also exceeds 98\% at recoil energies of \mbox{0.2 keV} and above for ER, and \mbox{1.3 keV} and above for NR. The measured trigger efficiency varies between 99\% and 100\% over the fiducial volume of the detector.