A comparative study of the energy resolution achievable with digital signal processors in X-ray spectroscopy

Interest for digital processing of signals from radiation detectors is subject to a growing attention due to its intrinsic adaptivity, easiness of calibration, etc. This work compares two digital processing methods: a multiple-delay-line (DL)/sup N/ filter and a least-mean-squares (LMS) adaptive filter for applications in high resolution X-ray spectroscopy. The signal pulse, as appears at the output of a proper analog conditioning circuit, is digitized: the samples undergo a digital filtering procedure. Both digital filters take advantage of the possibility of synthesizing the best possible weighting function with respect to the actual noise conditions. A noticeable improvement of more than 10% in energy resolution has been achieved with both systems with respect to state-of-the-art systems based on analog circuitry. In particular, the two digital processors are shown to be the best choice respectively: for on-line use with critical ballistic deficit conditions and for very-high-resolution spectroscopy systems, ultimately limited by 1/f noise.