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Sensing Gamma-Rays in Thick Pixelated Thallium Bromide Detectors With Application-Specific Integrated Circuits
Sensing Gamma-Rays in Thick Pixelated Thallium Bromide Detectors With Application-Specific Integrated Circuits
상세정보
- 자료유형
- 학위논문 서양
- 최종처리일시
- 20250211153146
- ISBN
- 9798384044871
- DDC
- 539.76
- 저자명
- Hall, Erik.
- 서명/저자
- Sensing Gamma-Rays in Thick Pixelated Thallium Bromide Detectors With Application-Specific Integrated Circuits
- 발행사항
- [Sl] : University of Michigan, 2024
- 발행사항
- Ann Arbor : ProQuest Dissertations & Theses, 2024
- 형태사항
- 116 p
- 주기사항
- Source: Dissertations Abstracts International, Volume: 86-03, Section: B.
- 주기사항
- Advisor: He, Zhong.
- 학위논문주기
- Thesis (Ph.D.)--University of Michigan, 2024.
- 초록/해제
- 요약Pixelated semiconductor gamma-ray detectors are uniquely suited to perform both gamma-ray spectrometry and imaging with the same device. These detectors can precisely record the energy deposited by an incident gamma ray and their planar-pixel electrode configuration enables three-dimensional position-sensing of the interaction. CZT has demonstrated great commercial success and research materials such as TlBr and Perovskites, such as cesium-lead bromide, have potential as alternatives to CZT. However, readout electronics and algorithms that can mate with these new materials are key components to their radiation detection capability. This work seeks to identify the gaps in the fabrication of pixelated TlBr gamma-ray detectors, using current readout technology and techniques, and suggests areas for further development.Electrodes made from various combinations of materials to include chromium, gold, palladium, and platinum provided the best spectroscopic performance. However, their performance generally worsened over time. Some samples showed a small improvement later, but not enough for their further use as gamma-ray detectors. Electrode refabrication failed to provide good results later, so electrode materials are likely diffusing into the detector bulk. Additionally, a small detector with thallium electrodes provided similarly good performance until failure, then was operated with a reverse-polarity positive bias for a similar time period. When tested again with a negative bias, it showed good performance again similar to its operation before failure.In larger detectors bonded to a carrier board, over days of operation, some event waveform tails show an increasing amount of extra signal, which degrades spectroscopic resolution. Events occurring near the pixel edges tend to show this extra tail signal while event waveforms in the pixel center tend to have a more consistent shape. Increased electron de-trapping around the pixel edges is a possible cause. A pixel-like pattern has also been observed on their planar cathodes, where patches of the cathode have disintegrated. It is possible that the silver epoxy used to bond the pixelated anode of the detectors to their carrier board is reacting with the planar cathode and causing the separation. The VAD-UMv2.2 ASIC is failing to record many events at its smallest dynamic range. This problem is exacerbated for detectors with greater electron trapping. Failure to record events in sub-optimal detectors makes characterization difficult or impossible. Increasing the preamplifier feedback resistance enabled the recording of more events in the middle depths, but events near the planar cathode were still missing. When using the smallest dynamic range, this ASIC's trigger shaper likely has a time constant that is too short for slow-rising waveforms in lower-mobility materials like TlBr. However, this ASIC's second-smallest dynamic range seemed to be better able to record more bulk events, even near the planar cathode. Another disadvantage is that its sampling window at a 2.5 MHz sampling rate is barely long enough to fully record events in TlBr at more sustainable operating biases like 1 kV/cm. The slowest sampling rate of 1.25 MHz would be beneficial for recording complete event waveforms but was not functioning. The H3DD-UMv4 ASIC is more suitable than the VAD-UMv2.2 ASIC for slower materials such as TlBr. It has more reliable slow sampling rates, a longer sampling window, and a wider span of trigger shaping times. It's slower trigger shaper time constant enables the recording of more low-amplitude events, which helps correctly categorize multi-pixel events and thus improves the energy resolution for single-pixel events.One detector showed consistent performance when operated from 0°C to +30°C. However, and extra signal loss was observed repeatedly at +40°C. Faster preamplifier decay at +40°C played a role in that signal loss.
- 일반주제명
- Nuclear engineering
- 일반주제명
- Electrical engineering
- 키워드
- Thallium bromide
- 기타저자
- University of Michigan Nuclear Engineering & Radiological Sciences
- 기본자료저록
- Dissertations Abstracts International. 86-03B.
- 전자적 위치 및 접속
- 로그인 후 원문을 볼 수 있습니다.
MARC
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■020 ▼a9798384044871
■035 ▼a(MiAaPQ)AAI31631415
■035 ▼a(MiAaPQ)umichrackham005648
■040 ▼aMiAaPQ▼cMiAaPQ
■0820 ▼a539.76
■1001 ▼aHall, Erik.
■24510▼aSensing Gamma-Rays in Thick Pixelated Thallium Bromide Detectors With Application-Specific Integrated Circuits
■260 ▼a[Sl]▼bUniversity of Michigan▼c2024
■260 1▼aAnn Arbor▼bProQuest Dissertations & Theses▼c2024
■300 ▼a116 p
■500 ▼aSource: Dissertations Abstracts International, Volume: 86-03, Section: B.
■500 ▼aAdvisor: He, Zhong.
■5021 ▼aThesis (Ph.D.)--University of Michigan, 2024.
■520 ▼aPixelated semiconductor gamma-ray detectors are uniquely suited to perform both gamma-ray spectrometry and imaging with the same device. These detectors can precisely record the energy deposited by an incident gamma ray and their planar-pixel electrode configuration enables three-dimensional position-sensing of the interaction. CZT has demonstrated great commercial success and research materials such as TlBr and Perovskites, such as cesium-lead bromide, have potential as alternatives to CZT. However, readout electronics and algorithms that can mate with these new materials are key components to their radiation detection capability. This work seeks to identify the gaps in the fabrication of pixelated TlBr gamma-ray detectors, using current readout technology and techniques, and suggests areas for further development.Electrodes made from various combinations of materials to include chromium, gold, palladium, and platinum provided the best spectroscopic performance. However, their performance generally worsened over time. Some samples showed a small improvement later, but not enough for their further use as gamma-ray detectors. Electrode refabrication failed to provide good results later, so electrode materials are likely diffusing into the detector bulk. Additionally, a small detector with thallium electrodes provided similarly good performance until failure, then was operated with a reverse-polarity positive bias for a similar time period. When tested again with a negative bias, it showed good performance again similar to its operation before failure.In larger detectors bonded to a carrier board, over days of operation, some event waveform tails show an increasing amount of extra signal, which degrades spectroscopic resolution. Events occurring near the pixel edges tend to show this extra tail signal while event waveforms in the pixel center tend to have a more consistent shape. Increased electron de-trapping around the pixel edges is a possible cause. A pixel-like pattern has also been observed on their planar cathodes, where patches of the cathode have disintegrated. It is possible that the silver epoxy used to bond the pixelated anode of the detectors to their carrier board is reacting with the planar cathode and causing the separation. The VAD-UMv2.2 ASIC is failing to record many events at its smallest dynamic range. This problem is exacerbated for detectors with greater electron trapping. Failure to record events in sub-optimal detectors makes characterization difficult or impossible. Increasing the preamplifier feedback resistance enabled the recording of more events in the middle depths, but events near the planar cathode were still missing. When using the smallest dynamic range, this ASIC's trigger shaper likely has a time constant that is too short for slow-rising waveforms in lower-mobility materials like TlBr. However, this ASIC's second-smallest dynamic range seemed to be better able to record more bulk events, even near the planar cathode. Another disadvantage is that its sampling window at a 2.5 MHz sampling rate is barely long enough to fully record events in TlBr at more sustainable operating biases like 1 kV/cm. The slowest sampling rate of 1.25 MHz would be beneficial for recording complete event waveforms but was not functioning. The H3DD-UMv4 ASIC is more suitable than the VAD-UMv2.2 ASIC for slower materials such as TlBr. It has more reliable slow sampling rates, a longer sampling window, and a wider span of trigger shaping times. It's slower trigger shaper time constant enables the recording of more low-amplitude events, which helps correctly categorize multi-pixel events and thus improves the energy resolution for single-pixel events.One detector showed consistent performance when operated from 0°C to +30°C. However, and extra signal loss was observed repeatedly at +40°C. Faster preamplifier decay at +40°C played a role in that signal loss.
■590 ▼aSchool code: 0127.
■650 4▼aNuclear engineering
■650 4▼aElectrical engineering
■653 ▼aThallium bromide
■653 ▼aPixelated semiconductor
■653 ▼aWaveform signal processing
■653 ▼aGamma-ray spectrometry
■690 ▼a0552
■690 ▼a0544
■71020▼aUniversity of Michigan▼bNuclear Engineering & Radiological Sciences.
■7730 ▼tDissertations Abstracts International▼g86-03B.
■790 ▼a0127
■791 ▼aPh.D.
■792 ▼a2024
■793 ▼aEnglish
■85640▼uhttp://www.riss.kr/pdu/ddodLink.do?id=T17165190▼nKERIS▼z이 자료의 원문은 한국교육학술정보원에서 제공합니다.
