Ballistic deficit correction in semiconductor detector spectrometers

At high energies the energy resolution of gamma -ray spectrometers using large-diameter coaxial germanium detectors can be dominated by ballistic-deficit effects, particularly when short processing times are used to permit high-rate operation. This results because that rise-time variations in the detector signal are reflected in amplitude fluctuations after the signals pass through pulse shapes. A method is described for compensating for these effects on a pulse-by-pulse basis, using the observation that the loss of amplitude for slowly rising signals is accompanied by a delay in the peak time of the shaped output signal. The simple analog corrector circuit uses a relationship whereby the amplitude deficit is roughly proportional to the square of the time delay in the peak. Results show considerable improvements in the energy resolution of germanium gamma -ray spectrometers at high energies.<>