Abstract / Description of output
Radon gas emanating from materials is of interest in environmental
science and also a major concern in rare event non-accelerator particle
physics experiments such as dark matter and double beta decay searches,
where it is a major source of background. Notable for dark matter
experiments is the production of radon progeny recoils (RPRs), the low
energy (~ 100 keV) recoils of radon daughter isotopes, which can mimic
the signal expected from WIMP interactions. Presented here are results
of measurements of radon emanation from detector materials in the 1
m3 DRIFT-II directional dark matter gas time projection
chamber experiment. Construction and operation of a radon emanation
facility for this work is described, along with an analysis to
continuously monitor DRIFT data for the presence of internal
222Rn and 218Po. Applying this analysis to
historical DRIFT data, we show how systematic substitution of detector
materials for alternatives, selected by this device for low radon
emanation, has resulted in a factor of ~ 10 reduction in internal radon
rates. Levels are found to be consistent with the sum from separate
radon emanation measurements of the internal materials and also with
direct measurement using an attached alpha spectrometer. The current
DRIFT detector, DRIFT-IId, is found to have sensitivity to
222Rn of 2.5 μBql‑1 with current analysis
efficiency, potentially opening up DRIFT technology as a new tool for
sensitive radon assay of materials.
Original language | English |
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Journal | Journal of Instrumentation |
Volume | 9 |
Publication status | Published - 1 Nov 2014 |