Radiation stability of high pressure xenon gamma-ray spectrometers

Spectrometric characteristics of High Pressure Xenon (HPXe) gamma-ray spectrometer "Ksenia" was studied during operation of this instrument onboard the orbital station "MIR". The energy resolution of this spectrometer is 3.5/spl plusmn/0.5% at E/sub /spl gamma//=511 keV and stable during period from May 1990 till May 1997. The position of 511 keV gamma line is also stable (/spl plusmn/1 channel or /spl plusmn/4 keV). The total number of trapped in radiation belt particles passing through the detector is 5/spl middot/10/sup 9/. The number of neutrons of atmospheric albino is 2/spl middot/10/sup 10/. No activated gamma-lines were found during the flight. After intensive activation (fluence of about 1.5/spl middot/10/sup 10/ neutrons) of a cylindrical HPXe spectrometer with a volume of Xe of about 6 liters few activated gamma-lines were registrated: E/sub /spl gamma//=164 keV, T/sub 1/2 /=11.92 from /sup 131/Xe/sub m/; E/spl gamma/=236 keV, T/sub 1/2 /=8.89 days from /sup 129/Xe, and E/spl gamma/=847 keV, T/sub 1/2 /=2.56 hours from /sup 56/Mn. The intensity of these lines is not large so it is possible to operate HPXe spectrometers even after intense irradiation.