Abstract
A coincidence gamma spectrometer has been used to measure the 134 Cs activity in the presence of intense interference from 137 Cs and from natural radioactivity in environmental samples. The coincidence spectrometer, with a large BGO scintillator for gating purposes and a HPGe detector for the coincident spectrum, is designed to enhance the coincidence full energy peak counting rate of 134 Cs and to suppress the single photon counting rate of 137 Cs as well as other natural radionuclides. An overall enhancement factor of 120 is obtained in coincidence while the interfering full energy peaks are substantially suppressed. Absolute counting efficiency of the coincidence spectrometer is calibrated for environmental samples with activity ratios of A( 134 Cs)/A( 137 Cs) down to 5 × 10 -5 . Other applications and the flexibility of the spectroscopic system are discussed. © 1991.