Material radiopurity control in the XENONnT experiment

Abstract

The selection of low-radioactive construction materials is of the utmost importance for rare-event searches and thus critical to the XENONnT experiment. Results of an extensive radioassay program are reported, in which material samples have been screened with gamma-ray spectroscopy, mass spectrometry, and ${}^{222}$Rn emanation measurements. Furthermore, the cleanliness procedures applied to remove or mitigate surface contamination of detector materials are described. Screening results, used as inputs for a XENONnT Monte Carlo simulation, predict a reduction of materials background ($\sim$17%) with respect to its predecessor XENON1T. Through radon emanation measurements, the expected ${}^{222}$Rn activity concentration in XENONnT is determined to be 4.2${(}_{-0.7}^{+0.5})\mu$Bq/kg, a factor three lower with respect to XENON1T. This radon concentration will be further suppressed by means of the novel radon distillation system.

References in corpus (10)

• Galactic Searches for Dark Matter
• First observation of two-neutrino double electron capture in ${}^{124}$Xe with XENON1T
• Gator: a low-background counting facility at the Gran Sasso Underground Laboratory
• Study and mitigation of spurious electron emission from cathodic wires in noble liquid time projection chambers
• Radon depletion in xenon boil-off gas
• Radon daughter removal from PTFE surfaces and its application in liquid xenon detectors
• Magnetically-coupled piston pump for high-purity gas applications
• Removal of long-lived ${}^{222}$Rn daughters by electropolishing thin layers of stainless steel
• Radon Daughter Plate-out onto Teflon
• Ultra-clean radon-free four cylinder magnetically-coupled piston pump