The requirements of analogue to digital converters in nuclear and X-ray spectrometry

Most nuclear radiation detectors produce an output whose amplitude is proportional to the incident particle energy. The techniques of converting this amplitude into energy bins has a history spreading over 50 years. The requirements placed on ADCs for spectrometry are somewhat different than those in most other applications. The differential nonlinearity (DNL) which in most commercial ADCs is between 0.5 and 1 least significant bits (LSB) has in spectrometry to be improved to better than 0.005 LSB. Techniques used to attain this are described. The advent of very high speed monolithic ADCs with conversions to 12 Bits and more has prompted a new look at the direct conversion of the detector output signal and subsequent digital filtering, to replace analogue filtering. The requirements of these ADCs for spectrometry are discussed