The Design, Implementation, and Performance of the LZ Calibration Systems

TL;DR

This paper details the design, implementation, and performance of calibration systems for the LZ dark matter detector, crucial for understanding detector responses and improving signal-background discrimination in rare-event searches.

Contribution

It provides a comprehensive description of the novel calibration systems used in the LZ experiment, highlighting their features, requirements, and performance for future applications.

Findings

Calibration systems effectively characterize detector responses.

Calibration improves signal-background discrimination.

Systems demonstrate reliable performance in a dark matter search environment.

Abstract

LUX-ZEPLIN (LZ) is a tonne-scale experiment searching for direct dark matter interactions and other rare events. It is located at the Sanford Underground Research Facility (SURF) in Lead, South Dakota, USA. The core of the LZ detector is a dual-phase xenon time projection chamber (TPC), designed with the primary goal of detecting Weakly Interacting Massive Particles (WIMPs) via their induced low energy nuclear recoils. Surrounding the TPC, two veto detectors immersed in an ultra-pure water tank enable reducing background events to enhance the discovery potential. Intricate calibration systems are purposely designed to precisely understand the responses of these three detector volumes to various types of particle interactions and to demonstrate LZ's ability to discriminate between signals and backgrounds. In this paper, we present a comprehensive discussion of the key features, requirements, and performance of the LZ calibration systems, which play a crucial role in enabling LZ's WIMP-search and its broad science program. The thorough description of these calibration systems, with an emphasis on their novel aspects, is valuable for future calibration efforts in direct dark matter and other rare-event search experiments.