Didenko H. Materials and photodiode detectors for charged particle registration in space

Українська версія

Thesis for the degree of Candidate of Sciences (CSc)

State registration number

0417U004221

Applicant for

Specialization

  • 05.02.01 - Матеріалознавство

17-10-2017

Specialized Academic Board

Д 64.169.01

Institute for single crystals NASU

Essay

In this work the choice of materials for creation of photodiode detector for charged particles registration has been grounded. Detailed study of advanced material properties has been provided to operate in space. It has been shown that CsI:Tl,CO3 crystal is characterized by uniform distribution of Tl+ and Na+ along cylindrical part of ingot. The same is thru for spectrometric characteristics like light yield and energy resolution. Contrary it the distribution of CO3- ions and value of millisecond afterglow is non-uniform as rule. It has been shown that it is possible to select the part of ingot with homogeneous distribution of all dopands and scintillation parameters. It has been shown that radiation hardness of selected aria can rich a value of 102 Gy and volume of uniform part can be more than 200 cm3. It has been shown that CsI:Tl,NO2 scintillation material is characterized by suppressed afterglow (up to 50% less) and spectrometric parameters are the same as for CsI:Tl,CO3 crystal. Energy resolution of 1.5% is obtained for 20 MeV-protons with Hamamatsu S5106 photodiode. Radiation hardness of CsI:Tl,NO2 material corresponds to dose of 7 103 Gy at -irradiation and fluence of >1012 см-2 at proton irradiation that coincides with requirements of BipiColombo mission to Mercury. Polymer composition on a base of enhancement powders TiO2 and MgO have been chosen for thin film reflectors. It has been shown that registration threshold can be decreased to 17 keV due to optimization of photodiode scintillator. The examples of selected materials application in space (telescope STEP-F, spectrometer SIXS) and on the Earth (dose calibrator for nuclear medicine) have been described.

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