Optical simulations of the XENONnT experiment

The XENON Dark Matter Project uses a dual-phase xenon time projection chamber (TPC) for a direct search for weakly interacting massive particles (WIMPs). The next operation phase, XENONnT, is currently under construction at Laboratori Nazionali del Gran Sasso (LNGS). Therefore, a new TPC was developed to maximize the active detector volume while keeping most of the infrastructure of XENON1T. This kind of detector is built to detect low intensity light signals, generated either directly by the recoil produced by the scattering processes of incoming particles (S1) or through proportional scintillation (S2). The light collection efficiency (LCE) of these signals depends on the position of interactions in the active volume and on optical properties of the detector materials. During operation and analysis of XENON1T, several aspects of the design revealed opportunities of further improvements, such as the geometrical arrangement of the PTFE components in the electroluminescence region. A recap of the design choices for XENON1T and XENONnT regarding optical properties as well as preliminary optical simulations of XENONnT are shown.