Papers by Keyword: Nuclear Radiation Detector

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Authors: Alexander M. Ivanov, Marina G. Mynbaeva, Anton V. Sadokhin, Nikita B. Strokan, Alexander A. Lebedev
Abstract: Nonequilibrium-charge transport has been studied in a structure with a Schottky barrier fabricated on a CVD-grown n-4H-SiC film. The charge introduced by single α-particles was recorded by nuclear spectrometric techniques. The maximum electric field strength in the structure was 1.1 MV/cm. The recorded charge as a function of the reverse bias applied to the structure shows a superlinear rise. Simultaneously, the width of the amplitude spectrum increased superlinearly, too. The observed effect is attributed to the initial stage of impact ionization. The manifestation of the process at unusually low fields (~1.0 MV/cm) is accounted for by specific features of the charge generation process. The carriers generated by a α-particle are found to be originally "heated". The results obtained allow prognostication of the appearance of SiC detectors of the "proportional counter" type in the near future. This is enabled by the advances made in the field of high-voltage electronics in obtaining in practice the required electric field strengths.
Authors: Ji Jun Zhang, Lin Jun Wang, Jian Huang, Ke Tang, Zhen Wen Yuan, Yi Ben Xia
Abstract: The Cd1-xMnxTe crystal is believed to be a good candidate to compete with Cd1-xMnxTe in the X-ray and γ-ray detector application. In this paper, Indium (In) doped Cd0.8Mn0.2Te (CdMnTe) ingots were grown by the modified Vertical Bridgman method. The as-grown crystals were characterized using Near-Infrared (NIR) transmission spectrum mapping of composition, X-ray double-crystal rocking curve measurement, I-V measurement and 241Am gamma rays radiation measurement. The Mn composition extracted from the NIR spectra at different axial and radial distances of the 30×40×2 mm3 CdMnTe wafers shown that the Mn concentration in the range of 0.19430.0008 to 0.2020.0025 mole fraction. The FWHM values of the X-ray rocking curves are of 40-80 arc sec, indicating a high crystalline perfection. The resistivity of the wafers is (2-3) ×1010Ω.cm. The CdMnTe planar detector irradiated by 241Am source shows the energy resolution of 8.5%.
Authors: Alexander M. Ivanov, Anton V. Sadokhin, Nikita B. Strokan, Alexander A. Lebedev, Vitalii V. Kozlovski
Abstract: Polarization effect characteristically occurs in detectors based on wide-bandgap materials at considerable concentrations of radiation defects. The appearance of an electromotive force in the bulk of a detector is due to the long-term capture of carriers at deep levels related to radiation centers. The kinetics and strength of the polarization field have been determined. The capture can be controlled by varying the detector temperature, with a compromise reached at the "optimal" temperature between the generation current and the position of the deepest of the levels whose contribution to the loss of charge via capture is negligible. It has been found that the depth of a level (related to the energy gap width) is close to 1/3, irrespective of a material. The optimal temperatures are strictly individual for materials.
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