Measurement of Outgassing Properties for Potential nEXO Materials

Neutrinoless double beta decay is a hypothetical rare nuclear decay process that can occur if neutrinos are Majorana particles. nEXO is a worldwide collaboration that aims to detect this decay with 5 tonnes of isotopically enriched Xenon (Xe-136) in a high voltage time projection chamber (TPC). nEXO reconstructs energy deposits through measurement of the ionization electrons and scintillation photons produced by a decay within the xenon. The more efficiently nEXO can detect these electrons, the more accurately the energy can be reconstructed. However, the presence of electronegative impurities in the TPC, which may diffuse out of the detector materials, reduces the number of collected electrons. In order to select ideal detector materials, we investigate potential nEXO samples by studying their diffusion coefficient associated with pertinent gaseous impurities as a function of temperature and time. These data are used to develop a model that compares the diffusion coefficient of various gasses through each nEXO sample.