The Dynamic Range of LZ

TL;DR

The paper discusses the design and capabilities of the LZ dark matter detector's electronics, emphasizing its dynamic range from low-energy nuclear recoils to high-energy electron recoils, enabling diverse physics studies.

Contribution

It introduces the electronics system of the LZ detector, optimized for a wide energy range and specific calibration and measurement requirements.

Findings

Achieves 70% efficiency at 3 photoelectrons threshold

Supports energy measurements from 1 keV to 3000 keV

Enables calibration of tritium, krypton, and Xe lines

Abstract

The electronics of the LZ experiment, the 7-tonne dark matter detector to be installed at the Sanford Underground Research Facility (SURF), is designed to permit studies of physics where the energies deposited range from 1 keV of nuclear-recoil energy up to 3,000 keV of electron-recoil energy. The system is designed to provide a 70% efficiency for events that produce three photoelectrons in the photomultiplier tubes (PMTs). This corresponds approximately to the lowest energy threshold achievable in multi-tonne time-projection chambers, and drives the noise specifications for the front end. The upper limit of the LZ dynamic range is defined to accommodate the electroluminescence (S2) signals. The low-energy channels of the LZ amplifiers provide the dynamic range required for the tritium and krypton calibrations. The high-energy channels provide the dynamic range required to measure the activated Xe lines.