A high efficiency device for the detection of radioactive xenon isotopes

A detector has been designed for the detection of sub-Becquerel amounts of the radioactive xenon isotopes 131mXe and 133Xe. High efficiency has been obtained by the condensation of the sample directly onto the surfaces of two closely spaced silicon surface-barrier detectors. The measurement of the 131mXe is based on the detection of the conversion electrons. The 133Xe measurement is obtained by detection of the 81 keV photon in a NaI detector that nearly surrounds the silicon detectors. The minimum detectable activity for 133Xe is 0.015 Bq. For a 131mXe sample with no 133Xe present, the minimum detectable activity is about 0.003 Bq.