Development of a cosmic veto gamma-spectrometer

• DOI: 10.1007/s10967-011-1566-0
• Publication Date: 2011-12-15T14:52:37Z
• Authors: J. L. Burnett; A. V. Davies
• Keywords: Gamma ray spectrometer; Liquid Scintillation Counting

Cosmic radiation contributes significantly towards the background radiation measured by a gamma-spectrometer. A novel cosmic veto gamma-spectrometer has been developed that provides a mean background reduction of 54.5%. The system consists of plastic scintillation plates operated in time-stamp mode to detect coincident muon interactions within an HPGe gamma-spectrometer. The instrument is easily configurable and provides improved sensitivity for radionuclides indicative of nuclear weapons tests and reactor incidents, including 140Ba, 95Zr, 99Mo, 141Ce, 147Nd, 131I, 134Cs and 137Cs. This has been demonstrated for Comprehensive Nuclear-Test-Ban Treaty applications to obtain the required 140Ba MDA of 24 mBq within 2 days counting. Analysis of an air filter sample collected during the Fukushima incident indicates improved sensitivity compared to conventional gamma-spectrometers.