ENHANCED DIGITAL SPECTROMETRY OF GAS PROPORTIONAL SCINTILLATION-COUNTER PULSES IN X-RAY-FLUORESCENCE APPLICATIONS

Pulse integration times of several microseconds are necessary to reduc e ballistic deficit in the signals from a gas proportional scintillati on counter. However, shorter integration times are desirable when rise time discrimination is applied. To meet both requirements, the pulse i s first integrated in the main amplifier with a short (0.1 mu s) integ ration time constant for risetime discrimination, followed by digital integration with a longer time constant. When applied to the pulse-hei ght distribution of x-rays from a Cd-109 source, this processing metho d improves the resolution and the peak-to-background ratio from 5.2% a nd 17, respectively, for the case of a 5 mu s analog integration time constant and no risetime discrimination, to 4.4% and 93, when a 0.1-mu s analog time constant and risetime discrimination and digital integr ation are applied. In the latter case, 92% of the peak-counting effici ency is retained.