Method and circuit arrangement for discriminating between pulses

Abstract

Alpha and beta particles containing samples are detected to generate deter pulses wherein the leading edge of the pulses rise particle specifically almost constantly during a predetermined time with the slope of the pulses generated by alpha particles being substantially greater than the slope of the pulses generated by the beta particles. This physical phenomenon which is substantially independent of the energy of the particles is utilized for discrimination to determine which type of particle produced the pulse. The linear starting region of the leading edge of the detector pulse is time discriminated in the nanosecond range. During the time given by the time discrimination, the detector pulses of alpha particles reach substantially higher amplitude values than the detector pulses generated by beta particles. The amplitude of the time discriminated detector pulse is determined by amplitude discrimination and is converted to trigger pulses which trigger a first counter for unequivocal alpha events or a second counter for unequivocal beta events. The very small portion of the detector pulses, whose amplitude obtained by time discrimination cannot be unequivocally associated with alpha or beta events, cause a third counter to be triggered which indicates the quality of the measurement.