CdTe Linear Pixel X-Ray Detector With Enhanced Spectrometric Performance for High Flux X-Ray Imaging

Abstract

International audienc

Measurement and modelling of anomalous polarity pulses in a multi-electrode diamond detector

“…Pulse height defects and charge losses [1], charge collection efficiency (CCE) losses and spectra distortion [4][5][6], ambipolar transient current signals [7] and anomalous polarity pulses [8,9] have been reported so far. Specifically, we adopt the "anomalous polarity pulse" term to refer to an induced charge pulse having the opposite polarity to what would be detected in a standard device with two large parallel electrodes [9].…”

“…As the maturity of the above-mentioned materials for radiation detection applications ensures a complete charge collection at the electrodes [5,7,12], charge sharing and related effects were naturally ascribed to carriers thermal diffusion in inter-electrode gaps [4,5,13,14] and to an extended charge cloud size [5,12,14,15].…”

“…It is worth noting that the geometry under investigation is equivalent, from the point of view of the electric-field topology, to many detectors with segmented electrodes in silicon [1,3,9] and CZT [7,15]. In fact, despite in such works the electric field is mostly perpendicular to the top active area of the detector, the excess charge carriers drift along the electric-field lines, which can be continuously deformed into the configuration shown in fig.…”

“…Such an interpretation is supported by the study of the CCE as a function of the generation position, which has been performed by neglecting any effect due to the charge cloud size and spread. In addition, differently from the significant contribution to charge-sharing phenomena in the case of the collection of carriers at the electrodes [5,7,12], diffusion cannot be regarded as a cause of anomalous polarity pulses due to the short carriers' lifetime in the material under test. The model is in agreement with the interpretation of results found in [1,4,8,9], ascribing the phenomenon to a selective recombination of carriers before collection at the electrodes; however, while in such works anomalous polarity pulses are induced by external factors (e.g., surface trap density or radiation damage effects) requiring additional assumptions on non-homogenous charge trap distributions, in our case they can be regarded an intrinsic effect, due to the charge transport properties of the material under test.…”

A 2D 4×4 channel readout ASIC for pixelated CdTe detectors for medical imaging applications

“…IXELATED Cadmium Telluride detectors are commonly used in X-ray and Gamma-ray detection since they are excellent absorbers for the high energy range X-ray photons and provide a large number of charge carriers for each incident gamma photon due to the fairly low ionization energy of 4.43 eV per electron-hole-pair [3,4,5]. Moreover, they can be used at Manuscript room temperature due to their energy band gap of 1.44 eV and can be produced with thickness up to 15 mm.…”