Radon Daughter Plate-out Measurements at SNOLAB for Polyethylene and Copper

摘要

Polyethylene and copper samples were exposed to the underground air at SNOLABfor approximately three months while several environmental factors weremonitored. Predictions of the radon-daughter plate-out rate are compared to theresulting surface activities, obtained from high-sensitivity measurements ofalpha emissivity using the XIA UltraLo-1800 spectrometer at SMU. From thesemeasurements, we determine an average $^{210}$Pb plate-out rate of 249 and 423atoms/day/cm$^{2}$ for polyethylene and copper, respectively, when exposed toradon activity of 135 Bq/m$^{3}$ at SNOLAB. A time-dependent model of alphaactivity is discussed for these materials placed in similar environmentalconditions.