PandaX-xT: a Multi-ten-tonne Liquid Xenon Observatory at the China Jinping Underground Laboratory

TL;DR

PandaX-xT is a proposed multi-tonne liquid xenon detector upgrade aiming to significantly enhance dark matter detection sensitivity, neutrinoless double beta decay searches, and astrophysical neutrino observations with ultra-low background levels.

Contribution

It introduces a large-scale, multi-purpose liquid xenon observatory with unprecedented sensitivity, advancing dark matter and neutrino physics research.

Findings

Nearly two orders of magnitude improvement in dark matter detection sensitivity

Potential to measure Majorana neutrino mass with 10-41 meV/$c^2$ sensitivity

Capability to explore ultra-rare interactions and astrophysical neutrinos

Abstract

We propose a major upgrade to the existing PandaX-4T experiment in the China Jinping Underground Laboratory. The new experiment, PandaX-xT, will be a multi-ten-tonne liquid xenon, ultra-low background, and general-purpose observatory. The full-scaled PandaX-xT contains a 43-tonne liquid xenon active target. Such an experiment will significantly advance our fundamental understanding of particle physics and astrophysics. The sensitivity of dark matter direct detection will be improved by nearly two orders of magnitude compared to the current best limits, approaching the so-called "neutrino floor" for a dark matter mass above 10 GeV/$c^2$, providing a decisive test to the Weakly Interacting Massive Particle paradigm. By searching for the neutrinoless double beta decay of $^{136}$Xe isotope in the detector, the effective Majorana neutrino mass can be measured to a [10 -- 41] meV/$c^2$ sensitivity, providing a key test to the Dirac/Majorana nature of neutrino s. Astrophysical neutrinos and other ultra-rare interactions can also be measured and searched for with an unprecedented background level, opening up new windows of discovery. Depending on the findings, PandaX-xT will seek the next stage upgrade utilizing isotopic separation on natural xenon.