Low-level gamma spectrometry using beta coincidence and Compton suppression

A low-level gamma-ray spectrometry system was developed using a Ge(Li) detector with 6% relative efficiency coupled to a 2π beta plastic detector for coincidence selection and a massive NaI(Tl) detector for Compton suppression. The integral background count rate for (50–1500) keV was 0.5 s−1 kg−1 (Ge), using only beta coincidences. With Compton suppression, a value of 0.25 s−1 kg−1 (Ge) was obtained. Spectra with and without Compton suppression were studied for 60Co, 137Cs and 152Eu point sources. Considerations are made concerning the Compton suppression advantages in different situations.