Portable spectrometer based on segmented HPGe detector with background suppression

The results of development of a portable spectrometer based on a segmented HPGe detector with background suppression for radioactive waste monitoring are presented. The detector has a planar and a coaxial segments, 68 mm in diameter and, respectively, 20 and 50 mm in length. The energy resolution of the planar segment was 1.3 keV on the energy of 122 keV and of the coaxial segment-2.5 keV on the energy of 1.33 MeV. The relative efficiency of the whole crystal was 60% at the energy of 1.33 MeV. The background suppression system has independent channels for amplifying and shaping the spectrometric pulses at the planar, coaxial and common outputs of the segmented detector. The planar and coaxial channels have a nonswitchable shaping time constant of 2 μs and the common channel-a switchable shaping time constant of 2 μs or 4 μs. The background suppression system is PC-controlled by the special software. Testing of the spectrometer with isotopes Cs-137 and Cs-137 + Co-57 has shown that the relative improvement in peak-Compton ratio for registration with and without suppression is 1.4 for the energy of 662 keV and exceeds 1.5 for the energy of 136 keV.