Abstract: Pulse pile-up rejection in nuclear and X-ray spectrometry is reduced or eliminated by providing the low-pass filter with a storage element which is charged to the value substantially by the voltage step generated by a quantum of radiation before the filtering process commences and only then effecting the filtering process. The step values before and after the rise of the step can be detected and with storage of the previous value, the energy proportional output can then be detected as the difference. The method and apparatus eliminates the rise time of the storage element as a factor contributing to pulse pile-up.

Abstract: Real-time correction of counting losses in the operation of a pulse-height analyzer, connected to the output of a radiation detector, is accomplished by establishing a gating interval at a time when the analyzer is available after processing the last detector pulse, this interval beginning at an instant delayed beyond the trailing edge of that last pulse by at least a predetermined rise time and ending with the leading edge of the next detector pulse. Test pulses generated during this gating interval are counted and their number is used to determine a probability ratio whose reciprocal constitutes a weighting factor; the digitized amplitude of each detector pulse addresses a corresponding memory cell whose contents are thereupon increased by the current weighting factor.