The advent of semiconductor detectors has revolutionized the broad field of X-rayspectroscopy. Semiconductor detectors, originally developed for particle physics, are nowwidely used for X-ray spectroscopy in a large variety of fields, as X-ray fluorescenceanalysis, X-ray astronomy and diagnostic medicine. The success of semiconductor detectorsis due to several unique properties that are not available with other types of detectors: theexcellent energy resolution, the high detection efficiency and the possibility of developmentof compact detection systems. Among the semiconductors, silicon (Si) detectors are the keydetectors in the soft X-ray band (< 15 keV). Si-PIN diode detectors and silicon drift detectors(SDDs), with moderate cooling by means of small Peltier cells, show excellent spectroscopicperformance and good detection efficiency below 15 keV. Germanium (Ge) detectors areunsurpassed for high resolution spectroscopy in the hard X-ray energy band (>15 keV) andwill continue to be the choice for laboratory-based high performance spectrometers.However, there has been a continuing desire for ambient temperature and compactdetectors with the portability and convenience of a scintillator but with a significantimprovement in resolution. To this end, numerous high-Z and wide band gap compoundsemiconductors have been exploited. Among the compound semiconductors, cadmiumtelluride (CdTe) and cadmium zinc telluride (CdZnTe) are very appealing for hard X-raydetectors and are widely used for the development of spectrometer prototypes for medicaland astrophysical applications.Beside the detector, the readout electronics also plays a key role in the development of highresolution spectrometers. Recently, many research groups have been involved in the designand development of high resolution spectrometers based on semiconductor detectors andon digital pulse processing (DPP) techniques. Due to their lower dead time, higher stabilityand flexibility, digital systems, based on directly digitizing and processing of detectorsignals (preamplifier output signals), have recently been favored over analog electronicsensuring high performance in both low and high counting rate environments.In this chapter, we review the research activities of our group in the development of highthroughput and high resolution X-ray spectrometers based on compound semiconductordetectors and DPP systems. First, we briefly describe the physical properties and the signalformation in semiconductor detectors for X-ray spectroscopy. Second, we introduce themain properties and critical issues of a X-ray detection system, highlighting thecharacteristics of both analog and digital approaches. Finally, we report on the spectroscopicperformance of a high resolution spectrometer based on a CdTe detector and a custom DPPsystem. As an application, direct measurements of mammographic X-ray spectra by usingthe digital CdTe detection system are also presented.
|Titolo della pubblicazione ospite||X-Ray Spectroscopy|
|Numero di pagine||26|
|Stato di pubblicazione||Published - 2012|