THE INFLUENCE OF COUNTING GEOMETRY AND LINING ON THE COMPTON CONTINUUM IN WELL-TYPE DETECTORS

To demonstrate the influence of counting geometry on the performance o f a well-type detector, as represented by the P/C- and P/T-ratio, Cs-1 37 and Co-60 sources were measured at 30 cm distance from the well and in the well; the latter both with and without a gold lining. Observed differences in the Compton continua are discussed. A significant incr ease in P/C- and P/T-ratios for Cs-137 is found when repositioning the source from 30 cm distance to a position in the well. For Co-60, only the P/T-ratio shows a similar behaviour. It is concluded that the det ector performs best when counting the source in the well without a lin ing. It is also concluded that, even though the P/T-ratio is preferred as an index of performance, only mono gamma emitting radionuclides sh ould be used when measuring P/C-ratios of a well-type detector.