Background Reduction in Charged-Particle Spectroscopy with Fast-Gated Electronics

In many experiments involving charged-particle spectroscopy using semiconductor detectors, the rate at which data can be obtained is frequently severely limited by large background fluxes of gamma rays and electrons. While the use of detectors whose sensitive depth is limited to that necessary to stop the charged particle of interest can substantially reduce the background contributions, pulse pile-up effects can obscure the desired spectral information through either accidental coincidence between an electron pulse and a heavy charged-particle pulse or through the simultaneous detection of several electrons. These pile-up effects can be minimized by the use of fast current-mode amplification which reduces the system resolving time essentially to the collection time of the detector, and a linear gate to permit integrating the eharge due to the selected events only. While such systems do not exhibit the excellent resolution of low noise charge-sensitive amplifiers, alpha particle line widths of 60 keV have been observed in the presence of electron fluxes as high as 108 electrons/cm2/second. Several examples of aceelerator, reactor and neutron spectroscopy experiments are given.