• 전기학회논문지
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• 제63권9호
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• pp.1253-1258
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• 2014

In this paper, we propose the fast and efficient detection method using the continuous measurement technique for the gamma-ray signal acquisition. This method is improved than the conventional method for the getting information of the radiation distribution. First, we implement the stereo radiation detection system using gamma-ray sensors and the motion controller. We apply continuous measurement technique to the gamma-ray detector and conduct gamma-ray irradiation test for the comparison of detection techniques. The results show that the continuous measurement technique has the high efficient performance than the conventional method.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2016년도 추계학술대회
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• pp.942-943
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• 2016

스테레오 감마선 탐지장치는 감마선을 신호를 측정하여 위치값을 통한 2차원의 감마선 영상을 생성 한후, 가시광영상과 중첩하여 실제 공간상의 감마선 분포를 나타낸다. 스테레오 감마선 탐지장치는 감마선 탐지센서를 포함하는 탐지부와 감마선 신호를 검출하는 신호측정부 그리고 탐지부의 위치를 제어하기 위한 모션제어부로 구성된다. 본 논문에서는 개별적으로 구성된 각각의 모듈을 효율적으로 운용하기 위한 시스템 운용 알고리즘을 개발하였고, 이를 통해 감마선 조사시험장에서 감마선에 대한 영상화 및 분포정보 출력을 확인하였다.

• Journal of Radiation Protection and Research
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• 제43권4호
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• pp.137-142
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• 2018

Background: Gamma-ray detectors having a thin window of a material with low atomic number can increase the true coincidence summing effects for radionuclides emitting X-rays or gamma-rays. This effect can make efficiency calibration or spectrum analysis more complicated. In this study, a Cu shield was tested as an X-ray filter to neglect the true coincidence summing effect by X-rays and gamma-rays in gamma-ray spectrometry, in order to simplify gamma-ray energy spectrum analysis. Materials and Methods: A Cu shield was designed and applied to an n-type high-purity germanium detector having an $X-{\gamma}$ summing effect during efficiency calibration. This was tested using a commercial, certified mixed gamma-ray source. The feasibility of a Cu shield was evaluated by comparing efficiency calibration results with and without the shield. Results and Discussion: In this study, the thickness of a Cu shield needed to avoid true coincidence summing effects due to $X-{\gamma}$ was tested and determined to be 1 mm, considering the detection efficiency desired for higher energy. As a result, the accuracy of the detection efficiency calibration was improved by more than 13% by reducing $X-{\gamma}$ summing. Conclusion: The $X-{\gamma}$ summing effect should be considered, along with ${\gamma}-{\gamma}$ summing, when a detection efficiency calibration is implemented and appropriate shielding material can be useful for simplifying analysis of the gamma-ray energy spectra.

• Nuclear Engineering and Technology
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• 제55권3호
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• pp.1031-1035
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• 2023

Neutron is an indirectly ionizing particle without charge, which is normally measured by detecting reaction products. Neutron detection system based on measuring gadolinium-converted gamma-rays is a good way to monitor the neutron because the representative prompt gamma-rays of gadolinium have low energies (79, 89, 182, and 199 keV). Low energy gamma-rays and their high attenuation coefficient on materials allow the simple design of a detector easier to manufacture. Thus, we designed a cadmium zinc telluride detector to investigate feasibility of simultaneous detection of gamma-rays and neutrons by using the Monte-Carlo simulation, which was divided into two parts; first was gamma-detection part and second was gamma- and neutron-simultaneous detection part. Consequently, we confirmed that simultaneous detection of gamma-rays and neutrons could be feasible and valid, although further research is needed for adoption on real detection.

• 분석과학
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• 제35권2호
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• pp.69-81
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• 2022

The method of measuring and classifying the energy category of neutrons directly using raw data acquired through a CZT detector is not satisfactory, in terms of accuracy and efficiency, because of its poor energy resolution and low measurement efficiency. Moreover, this method of measuring and analyzing the characteristics of low-energy or low-activity gamma-ray sources might be not accurate and efficient in the case of neutrons because of various factors, such as the noise of the CZT detector itself and the influence of environmental radiation. We have therefore developed an efficient method of analyzing radiation characteristics using a neutron and gamma-ray analysis algorithm for the rapid and clear identification of the type, energy, and radioactivity of gamma-ray sources as well as the detection and classification of the energy category (fast or thermal neutrons) of neutron sources, employing raw data acquired through a CZT detector. The neutron analysis algorithm is based on the fact that in the energy-spectrum channel of 558.6 keV emitted in the nuclear reaction ¹¹³Cd + ¹n → ¹¹⁴Cd + in the CZT detector, there is a notable difference in detection information between a CZT detector without a PE modulator and a CZT detector with a PE modulator, but there is no significant difference between the two detectors in other energy-spectrum channels. In addition, the gamma-ray analysis algorithm uses the difference in the detection information of the CZT detector between the unique characteristic energy-spectrum channel of a gamma-ray source and other channels. This efficient method of analyzing radiation characteristics is expected to be useful for the rapid radiation detection and accurate information collection on radiation sources, which are required to minimize radiation damage and manage accidents in national disaster situations, such as large-scale radioactivity leak accidents at nuclear power plants or nuclear material handling facilities.

• 센서학회지
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• 제25권5호
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• pp.333-336
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• 2016

In this study, a beta monitoring sensor was developed as a part of basic research for quantitative beta monitoring underwater, and its performance was evaluated using a calibration source. A beta detection sensor was manufactured by using SiPM(silicon photomultiplier) and $CaF_2$:Eu, YAG:Ce, YAP:Ce scintillator. A large-area light guide was introduced to improve beta-ray detection efficiency. As calibration sources, the Beta source $^{90}Sr$, which is the main fission product of a nuclear accident, and the gamma source $^{137}Cs$ are used. In the performance evaluation, it is confirmed that scintillator $CaF_2:Eu$ gives the highest beta-ray detection response. Compared to gamma ray, beta-ray detection responsivity and detection efficiency are verified. Therefore, this study is expected to contribute to basic research in the development of an underwater beta-ray monitoring system.

• 전자공학회논문지
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• 제52권4호
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• pp.197-203
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• 2015

전 세계적으로 전력생산을 위해 원전 증설이 지속적으로 증가하고 있으며 이에 따라 노후 원전에 대한 해체 및 원전사고에 대한 관심이 증가하고 있다. 원전 사고 시 발생되는 감마선원의 누출은 신속하고 정확한 탐지해야 그 피해를 최소화 시킬 수 있다. 기 개발된 장비는 선원에 대한 방향정보만을 나타내고 있어 정확한 공간상의 분포를 알 수 없다. 본 논문에서 개발한 스테레오 감마선탐지장치는 누출된 감마선원에 대한 분포를 측정할 수 있도록 구현하고 거리탐지를 위한 알고리즘을 적용하였다. 거리탐지를 위하여 스테레오 보정을 LED광과 보정패턴을 사용하여 진행하였고, LED 광원과 감마선원을 대상으로 성능시험을 진행하였다. 성능시험 결과 두 실험에서 5%이하의 오차를 갖게 됨을 확인하였다. 본 논문의 결과는 향후 고속 경량화 된 감마선 영상화 장치 개발을 위한 자료로 활용될 것이다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2015년도 추계학술대회
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• pp.1100-1102
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• 2015

본 논문에서는 스테레오 기반 감마선원 탐지장치를 통해 감마선원을 포함하는 공간을 래스터 스캔방식으로 스캔하여 가시광영상과 감마선영상을 획득하고, 스테레오 감마선 탐지장치로부터 선원까지의 거리와 방향에 대한 3차원 정보 획득 및 가시화를 수행하였다. 탐지장치의 구성은 감마선원 탐지를 위한 방사선 검출부, 선원탐지를 위해 래스터스캔방식의 스캔을 위한 팬틸트 그리고 가시광영상을 위한 CCD 카메라로 이루어진다. 선원에 대한 공간분포를 측정하기 위해 스테레오 구조의 장치를 구현하였으며 스테레오 영상획득을 위해 CCD 카메라와 감마선 탐지장치는 각각 2대로 구성하였다. 탐지선원에 대한 분포를 나타내기 위해 감마선 탐지 장치와 가시광 카메라에 대한 보정을 수행하였고, 각각의 카메라에 대한 스테레오 보정을 수행한 후 가시광영상과 감마선영상 중첩을 통해 감마선원에 대한 분포를 나타내었다. 좌, 우 분포영상에 대한 정류화처리 후 스테레오 영상에 대한 가시화결과를 도출하였다.

• Journal of Radiation Protection and Research
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• 제26권4호
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• pp.393-398
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• 2001

매년 병원에서 사용 후 폐기되는 비가연성 폐기물은 ${\gamma}$-선과 ${\beta}$-선을 방출하지만 방사능은 주변방사능 수준으로 매우 낮다. 이를 측정하기 위한 기존의 방법은 비효율적이고 복잡하므로, 좀더 간단한 방법이 긴요하다. 본 논문에서는 측정 방사선의 특성상 핵종에 따라 다른 측정방법을 사용하였는데, ${\gamma}$-선 방출 핵종은 표준시료로부터 효율곡선식을 도출하여 미지의 방사능을 측정하였다 ${\beta}$-선 방출 핵종은 Monte Carlo 시뮬레이션을 통해 계측 효율을 예측하고 표면장벽형계측기로 측정하여 미지의 방사능 양을 결정하는 새로운 방법을 제시하였다. 연구결과에 의하면 이론적 계산치와 표면장벽형 계측기를 이용하면 전처리를 필요로하는 액체섬광계수기를 이용하지 않고 또한 계측효율을 결정하기 위한 비경제적인 표준시료 측정시험과정 없이도 저에너지 방사선을 약 17% 오차 범위내에서 결정할 수 있다고 판단된다.

• Nuclear Engineering and Technology
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• 제51권1호
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• pp.263-268
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• 2019

The $^3He$ proportional chamber is widely used for neutron measurement owing to its high neutron detection efficiency and simplicity for gamma-ray rejection. In general, the neutron and gamma-ray signals obtained from the $^3He$ proportional chamber can be easily separated by the difference in the pulse heights. However, for a high gamma-ray field, the gamma-ray signal cannot be precisely eliminated by the pulse height due to gamma-ray pulse pileup which causes the pulse height of gamma-ray pulse to increase and making the pulses due to neutrons and gamma rays indistinguishable. In this study, an improved algorithm for $n/{\gamma}$ discrimination using a parameter, which is the ratio of the rise time to the pulse height, is proposed. The $n/{\gamma}$ discrimination performance of the algorithm is evaluated by applying it to $^{252}Cf$ neutron signal separation from various gamma-ray exposure rate levels ranging 0.1-5 R/h. The performance is compared to that of the conventional pulse-height analysis method in terms of the gamma elimination ratio. The suggested algorithm shows better performance than the conventional one by 1.7% (at 0.1 R/h) to 70% (at 5 R/h) for gamma elimination.