XAX: a multi-ton, multi-target detection system for dark matter, double beta decay and pp solar neutrinos

Understand

A multi-target detection system XAX, comprising concentric 10 ton targets of 136Xe and 129/131Xe, together with a geometrically similar or larger target of liquid Ar, is described.

• Each is configured as a two-phase scintillation/ionization TPC detector, enhanced by a full 4pi array of ultra-low radioactivity Quartz Photon Intensifying Detectors (QUPIDs) replacing the conventional photomultipliers for detection of scintillation light.
• It is shown that background levels in XAX can be reduced to the level required for dark matter particle (WIMP) mass measurement at a 10^-10 pb WIMP-nucleon cross section, with single-event sensitivity below 10^-11 pb.
• The use of multiple target elements allows for confirmation of the A^2 dependence of a coherent cross section, and the different Xe isotopes provide information on the spin-dependence of the dark matter interaction.