XENON1T is currently the largest liquid xenon detector in the search for dark matter. To fully exploit the capabilities of the ton-scale target mass, a thorough understanding of radioactive background sources is required. In this paper we use the full data of the main science runs of the XENON100 experiment that were taken over a period of about 4 years to asses the target-intrinsic background sources radon (Rn-222), thoron (Rn-220) and krypton (Kr-85). We derive distributions of the individual radionuclides inside the detector (see Figure below) and quantify their abundances during the main three science runs. We find good agreement with external measurements of radon emanation and krypton concentrations, and report an observed reduction in concentrations of radon daughters that we attribute to the plating-out of charged ions on the negatively biased cathode.
The preprint of the full study is available on arXiv:1708.03617.
Figure: Spatial distributions of the various radon populations identified in XENON100.