Safeguards Analytical Laboratory
Low-Level Gamma Spectrometric Screening of Environmental Samples
Immediately after receipt, environmental samples are measured with a low-background gamma spectrometer system, shown below. The spectrometer is based on a 90% efficient coaxial germanium detector enclosed in a high-purity lead shield of 10 cm thickness. The samples, contained in Marinelli beakers, are placed in a 15-position sample changer and counted for 1 hour each to provide a gamma spectrum in the energy range from 5KeV to 3 MeV. The total gamma activity, corrected for background, is obtained by this method and if suficient activity is detected, an evaluation of the spectral peaks can be performed to estimate the activity in Bq/sample of individual gamma emitting isotopes such as 60Co, 95Zr, 106 Ru, 134Cs, 137Cs and 241Am.
Low-Level Gamma Spectrometer