Quasi-optimum gamma and X spectroscopy based on real-time digital techniques

An adaptive, self-calibrated instrument for gamma- and X-ray digital spectr oscopy is proposed and demonstrated. Most of the typical processing feature s (pole-zero cancellation, baseline restoration, and shaping) are digitally implemented and optimized. Initialization is performed through a software procedure, which makes the system particularly flexible and allows periodic al adaptivity. It is shown that spectroscopy performances are achieved even while using low-cost, low-frequency (5 Ms/s), and relatively low-resolutio n (12-bit) AD converters. The ADC differential nonlinearity (DNL), for exam ple, is improved of two orders of magnitude, as estimated over the Compton shoulder of a Co-60 spectrum, owing to an equivalent built-in sliding-scale effect. Using the system with an high-purity germanium (HPGe) detector a r esolution of 1.9 keV FWHM (1.6 parts per thousand) is obtained on the 1.17 MeV spectral line of a Co-60 source. An Integral Nonlinearity (INL) of 0.3 parts per thousand, is measured in the range from 0.2 to 2 MeV from the spe ctral lines delivered by an Eu-152 source in such range. (C) 2000 Elsevier Science B.V. All rights reserved.