222Rn emanation into vacuum

Observation of annual modulation induced byγrays from (α,γ) reactions at the Soudan Underground Laboratory

“…Therefore, the chance of radon particles themselves entering the detector liquid volume via diffusion is close to zero. The radon emanation measured from an aluminum metal plate [34] is <0.5 per squared meter per hour, or ∼1.4×10 -8 cm -2 s -1 . Thus, this process cannot be responsible for the observed annual modulation signal.…”

The SNO+ experiment

“…Emanation of 222 Rn from the aluminum was estimated by γ counting 226 Ra from a production sample and applying a scaling factor that provides the emanation from the bulk activity. This factor was obtained in two ways: a calculation based on the diffusion length from [88] and from a more direct measurement using ZnS(Ag) coated decay cells in [89]. Both the central rope and umbilical drive motors have a high radon emanation, and are therefore isolated from the rest of the box atmosphere by two gas-tight boxes equipped with ferrofluidic vacuum-grade rotary couplings.…”

Design and Construction of the DEAP-3600 Dark Matter Detector

“…SNOLAB has a well-established gamma assay program; a 200 cm 3 highpurity germanium well detector (Princeton Gamma-Tech Instruments, Inc.) [39] was purchased and installed at SNOLAB to meet the assay requirements for the DEAP experiment. An inventory of gamma assay measurements A new radon emanation measurement system constructed at Queen's University, similar to that described in [41], was used to qualify and select detector materials. Materials are loaded into a vacuum chamber, the chamber is evacuated, and the material is then allowed to emanate into vacuum before the Rn atoms are collected using a cold trap.…”