High sensitivity radon emanation measurements

The presented radon detection technique employs miniaturized ultra-low background proportional counters. 222Rn samples are purified, mixed with a counting gas and filled into a counter using a special glass vacuum line. The absolute sensitivity of the system is estimated to be 40 μBq (20 222Rn atoms). For emanation investigations two metal sealed stainless steel vessels and several glass vials are available. Taking into account their blank contributions, measurements at a minimum detectable activity of about 100 μBq can be performed.