XLZD & Future Detector Research

XLZD science observatory
(From the XLZD design book. See arXiv:2410.17137)

Overview

The XLZD experiment is a proposed next-generation dark matter experiment with 60-80 tonnes of active liquid xenon. XLZD will be a successor to the LZ experiment and will have unprecedented sensitivity to WIMP dark matter down to the neutrino fog. It will also have competitive neutrinoless double beta decay sensitivity, as well as sensitivity to other dark matter candidates and neutrino sources.

SLAC is actively involved in R&D for XLZD, including developing novel methods to remove radon from liquid xenon. Betas from the radon decay chain are one of the dominant backgrounds in searching for WIMPs. SLAC is also involved in developing liquid-phase instrumentation, including a circulation pump, as well as designing and building high voltage electrode grids.

ReLIC

The Removal of Liquid Impurities via Chromatography (ReLIC) system in the Liquid Nobel Test Facility (LNTF) at SLAC tests materials for their use in removing contaminants from liquid Xe. Chromatography refers to the separation of different materials in a solution by passing them through a media that delays their passage at different rates.

Radon is a significant background in liquid xenon dark matter search experiments. Since radon is a product of the uranium and thorium decay chains, and these are ubiquitous in materials, radon is continuously emanated into experiments like LZ. Radon can be removed at a low rate with chromatography in the gas phase but that is not scalable to large detectors, such as the proposed XLZD, where its impact as a source of backgrounds is larger. Radon removal in liquid phase, if successful, would overcome this scalability issue and help XLZD in reducing its backgrounds. ReLIC hopes to demonstrate the viability of radon removal in liquid.

liam_and_simran

Liquid Phase Pump

Another R&D project for XLZD is the development of a custom cryogenic circulation pump, with the goal of circulating Xenon in its liquid phase. Compared to the current method of gas phase purification, this aims to increase the circulation throughput as well as energy efficiency of the purification system, all while providing a cheap and flexible pumping solution to future projects.