Characterization of Cadmium Telluride Based Pixelated Photon-Counting Detectors and Finetuning of the Electronic Readout System

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http://urn.fi/URN:NBN:fi:hulib-202006082645
Title: Characterization of Cadmium Telluride Based Pixelated Photon-Counting Detectors and Finetuning of the Electronic Readout System
Author: Nincă, Ilona Ştefana
Contributor: University of Helsinki, Faculty of Science
Publisher: Helsingin yliopisto
Date: 2020
Language: eng
URI: http://urn.fi/URN:NBN:fi:hulib-202006082645
http://hdl.handle.net/10138/315916
Thesis level: master's thesis
Degree program: Alkeishiukkasfysiikan ja astrofysikaalisten tieteiden maisteriohjelma
Master's Programme in Particle physics and Astrophysical Sciences
Magisterprogrammet i elementarpartikelfysik och astrofysikaliska vetenskaper
Specialisation: Alkeishiukkasfysiikka ja kosmologia
Particle Physics and Cosmology
Elementarpartikelfysik och kosmologi
Discipline: none
Abstract: Cadmium Telluride (CdTe) has a high quantum efficiency and a bandgap of 1.44 eV. As a consequence, it is being used to efficiently detect gamma rays. The aim of this thesis is to explore the properties of the CdTe pixelated detector and the procedures conducted in order to fine-tune the electronic readout system. A fully functional CdTe detector would be useful in medical imaging techniques such as Boron Neutron Capture Therapy (BNCT). BNCT requires a detector with a good energy resolution, a good timing resolution and a good stopping power. Although the CdTe crystal is a promising material, its growing process is difficult due to the fact that different types of defects appear inside the crystal. The quality assurance process has to be thorough in order for suitable crystals to be found. An aluminum oxide layer (Al2O3) was passivated onto the surface of the crystal. The contacts for both sides were created using Titanium Tungsten (TiW) and gold (Au) sputtering deposition, followed by an electroless nickel growth. I tested the CdTe pixelated detector with different radioactive sources such as Am-241, Ba-133, Co-57, Cs-137 and X-ray quality series in order to study the sensitivity of the device and its capacity to detect gamma and X-rays.
Subject: CdTe
BNCT
ROC


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