APPLICATION OF PULSE-SHAPE DISCRIMINATION TECHNIQUE TO IMPROVE THE ENERGY RESOLUTION OF A GAS SCINTILLATION PROPORTIONAL COUNTER

Pulse shape discrimination technique has been applied to improve the e nergy resolution of a single wire anode (SWA) gas scintillation propor tional counter (GSPC). Resolution at 5.9 keV photon energy is improved from 33% to 16% by suppressing pulses due to interactions in the scin tillation production region (SPR) in a 1.7 mm diameter rod anode cylin drical design GSPC operated with Ar + 2.5% N2 in continuous flow. For the optimum operating conditions of the GSPC the rise time of the puls es due to 5.9 keV X-rays was typically 300 ns for interactions outside the SPR and a broad continuum from 300 ns down to about 40 ns for int eractions inside the SPR. In order to select a certain narrow time win dow a special time to amplitude converter unit was developed with a ti me resolution capability to distinguish pulses having rise times diffe ring only by a few ns.