GEOMETRY-EFFECTS IN WELL-TYPE GE-DETECTORS DUE TO THE INTRODUCTION OFHIGH-Z LININGS

In well-type detectors and other highly efficient geometries, the comb ined effects of sample self-absorption involving low-energy gamma-rays and coincidence summing of a low- and a high-energy photon often infl uence the entire gamma-spectrum of a radionuclide. For well-type detec tors, these effects are well understood and it should be possible to c orrect for these effects analytically. Another possibility to deal wit h these effects is to prevent the low-energy gamma-rays from reaching the detector by lining the well with a high-Z material, as was suggest ed in the past. We present a series of measurements which indicates th at the problems resulting from sample self-absorption and coincidence summing should be treated analytically rather than by attempts to elim inate the effects by means of a lining.