Radionuclide Identifier For Gamma Analysis - Riga

A hand-held HPGe spectrometer with a hybrid cooling system is developed. The cooling system of the spectrometer is liquid nitrogen-free and provides optimal energy resolution for a planar HPGe detector. It contains a cryoaccumulator, which is cooled to the melting point by a detachable Stirling-cycle cryocooler. When cooled the cryoaccumulator works as a thermal buffer keeping the temperature of the detector low-enough and stable for the proper HPGe detector operation. The cooling time of the cryoaccumulator from room temperature is 7 hours and an autonomous operation time of the device is 4 hours. The weight of the instrument carried by the operator during measurements is 3.9 kg. The weight of the docking station based on the cryocooler is 4.5 kg. The name of the device is RIGA - Radionuclide Identifier for Gamma Analysis. In the article, the thermal and vacuum properties of the cryostat, as well as mechanical and spectrometric characteristics of the device, are presented. The instrument is created for nuclear safeguards inspectors for such applications as U enrichment measurements and Pu isotopic composition verification with MGAU, MGA, and FRAM software codes.