Triple Coincidence Radioxenon Detector

The Automated Radioxenon Sampler/Analyzer (ARSA) built by Pacific Northwest National Laboratory (PNNL) is on e of the world’s most sensitive systems for monitoring the four radioxenon isotopes 133Xe, 133mXE, 131mXe and 135Xe. However, due to size, weight and power specifications appropriate to meet treaty-monitoring requirements; the ARSA is unsuitable for rapid deployment using modest transportation means. To transition this technology to a portable unit can be easily and rapidly deployed can be achieved by significant reductions in size, weight and power consumption if concentration were not required. As part of an exploratory effort to reduce both the size of the air sample and the gas processing requirement PNNL has developed an experimental nuclear detector to test and qualify the use of triple coincidence signatures (beta, conversion electron, x-ray) from two of the radioxenon isotopes (135Xe and 133Xe) as well as the more traditional beta-gamma coincidence signatures used by the ARSA system. The additional coincidence requirement allows for reduced passive shielding, and makes it possible for unambiguous detection of 133Xe and 153Xe in the presence of high 222Rn backgrounds. This paper will discuss the experimental setup and the results obtained for a 133Xe sample with and without 222Rn as an interferencemore » signature.« less