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GaP Photodiode와 산화물 섬광체를 이용한 원격측정 방사선량계 특성 분석

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Abstract
As applications of radiation in industrial and medical fields expand, high-tech radiation sensor production and measurement methods are developing. For example, ionization chamber, which is the most commonly used in the measurement of radiation absorbed dose, can be measurable in real time, yet it has problems such as low spatial resolution or complex correction process, caused by the volume and component materials of the detector. Also, Metal Oxide Field Effect Semiconductor Transistor (MOSFET), which is used in medical fields, has fine spatial resolution with small sensor part and measure dose at many points at the same time. However, it is uneconomical to measure in the hish dose rate fields since it is depletable and has a limited life. Alanine chemical dosimeter shows an exact dose and low deviation; it is has a disadvantage of decoding dose rate and the form of energy only with an expensive decoder since it cannot distinguish them directly. Therefore, the development of a new dosimeter to measure radiation in real time has been required. In order to compensate the weak points, the dosimeter, combining optic-fiber and scintillator, has a high spatial resolution since it makes the volume of scintillator in sensor part small. In addition, dose measurement is exact and easy, as measuring the amount of scintillation in proportion to dose. Also, it is not affected by electromagnetic wave and can measure dose in real time by using optic fiber, which is optical transfer medium. In this study, dosimeter has been created, combining oxide scintillator and plastic optical fiber and connecting GaP photodiode. After finding Calculated results, from MCNPX code and current changes of the photodiode which is measured by distance between sensors, changes of normalized distribution with dose rate of ionization chamber, which is measured at the same point, and transmutation constant which is converted by linearity, resulting from current and dose rate, the researchers analyzed the possibility of dosimeter by comparing dose rate. Several types of scintillators such as BGO(Bi4Ge3O12), CWO(CdWO4), and LYSO(Lu5Y2SiO5) were used in the sensor part of the dosimeter. Also, 60CO source of 5400Ci, obtained from the radiation room of applied radiological science research institute in Jeju National University, was used. The error between dose rate of transmutation constant and that of ionization chamber was 0.4~50% in BGO scintillator, which was not almost right; the error in CWO and LYSO was within 8% in high dose field with a few errors in whole part. The results of normalized distribution in BGO scintillator showed high deviation with different aspects of change as measured at the point which distance between dose and sensor is 20cm. The results of normalized distribution in CWO and LYSO scintillators were similar to inonization chamber and aspect of normal distribution change of MCNPX code.
Author(s)
김재경
Issued Date
2011
Type
Dissertation
URI
http://dcoll.jejunu.ac.kr/jsp/common/DcLoOrgPer.jsp?sItemId=000000005303
Alternative Author(s)
Kim, Jae-Kyoung
Affiliation
제주대학교
Department
대학원 에너지응용시스템학부 에너지공학과
Advisor
박재우
Table Of Contents
LIST OF FIGURES ⅲ
LIST OF TABLES ⅵ
SUMMARY ⅶ


Ⅰ. 서 론 1

1. 연구의 필요성 1
2. 국내외의 연구동향 2
(1) 유기섬광체와 광섬유를 결합한 방사선 센서 2
(2) 무기섬광체와 광섬유를 결합한 방사선 센서 6

Ⅱ. 선량계 모형 구성 및 제작 9

1. 섬광체 sensor, 섬광체 case, 플라스틱 광섬유, Photodiode의 구성 9
(1) 섬광체 sensor의 구성 9
(2) 섬광체 case의 구성 11
(3) 플라스틱 광섬유의 구성 13
(4) Photodiode의 구성 14

2. 선량계 모형 평가 실험방법 15
(1) 실험방법 16
(2) 전리함 측정방법 17
(3) MCNPX code 계산 18

Ⅲ 결과 및 고찰 20

1. 전리함으로 측정한 결과의 선형성 비교 20
2. 변환상수 비교 28
3. 정규화 분포 비교 37
(1) 전리함으로 측정한 결과 37
(1) MCNPX code로 측정한 결과 42


Ⅳ 결론 47

참 고 문 헌 49
감사의 글
Degree
Master
Publisher
제주대학교 대학원
Citation
김재경. (2011). GaP Photodiode와 산화물 섬광체를 이용한 원격측정 방사선량계 특성 분석
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Faculty of Applied Energy System > Energy and Chemical Engineering
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