Both the current XENONnT experiment and the future XLZD experiment consist of a time projection chamber (TPC), which is used for the direct detection of dark matter. With the XENONnT experiment, which is located in the underground laboratory Laboratori Nazionali del Gran Sasso (LNGS) in Italy, a large part of the parameter range of spin-independent WIMP nuclear scattering has already been tested with an active target of 8.6 tons of liquid xenon. The next generation xenon detector, XLZD, will be able to achieve unprecedented sensitivity in this parameter range as well as explore several other scientific channels with an active target material of 60-80 tons of liquid xenon combined with an ultra-low background environment.

 

The dual-phase TPC is a cylindrical volume containing a layer of gaseous and a layer of liquid xenon. The top and bottom planes of the cylindrical volume are covered with photosensors to record events in the detector. When energy is deposited in the liquid xenon, both scintillation light and ionization is produced. The light is promptly measured by the photosensor and is recorded as the “S1” signal. The electrons are drifted through the TPC using an electric field until the reach the liquid-gas interface. At which point, a stronger electric field is applied to extract and accelerate the electrons through the gaseous xenon, creating secondary scintillation light that is recorded as the “S2” signal. The ratio between the S1 and S2 signal is used to distinguish between electron-recoil and nuclear-recoil interaction.