• 한국의학물리학회지:의학물리
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• 제25권2호
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• pp.95-99
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• 2014

병원을 포함해서서 방사선 물질을 사용하는 모든 사업장에서 방사선 물질의 모니터링은 방사선 안전에 가장 중요한 요소의 하나이다. 본 연구는 방사선 모니터링 시스템에 있어서 GEM 검출기의 활용 가능성을 알아보기 위한 선행 연구로서, GEM 검출기를 제작하고 CdTe 검출기와의 상대적 효율을 구한 결과, 베타와 감마선에 대한 평균 상대 효율이 각각 72%와 4%로서 매우 우수한 성능을 나타냄을 보였다.

• Journal of Radiation Protection and Research
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• 제30권1호
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• pp.35-37
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• 2005

한국원자력연구소의 방사선 검출기 연구팀에서는 가스 전자 증폭기를 이용하여 고효율 중성자 검출기를 개발하고 있다. 이중 가스 전자 증폭기를 제작하였고 Ar/Isobutane 혼합기체에서 동작시켰다. 고효율 중성자 검출기에 적용하기 위해서 다중 가스 전자 증폭기 포일 양면에 중성자 변환 물질인 $^6Li$ 또는 $^{10}B$를 코팅하는 것이 고려되었다. 중성자 검출을 위한 박막의 최적화된 두께를 MCNP와 SRIM으로 계산하였다. 중성자 검출 효율은 박막을 구성하는 화합물과 박막 두께를 변화시키면서 계산하였다. 열중성자는 drift plate에 중성자 반응 박막을 입힌 GEM 검출기에 의해서 측정되있다.

• Nuclear Engineering and Technology
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• 제52권6호
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• pp.1277-1281
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• 2020

A novel ceramic Gas Electron Multiplier (GEM) has been developed to meet the demand of high counting rate for the neutron detection which is an alternative to ³He-based detector at China Spallation Neutron Source (CSNS). An experiment was performed to measure the neutron transmittance of ceramic-GEM and FR4-GEM at the small angle neutron scattering (SANS) instrument. The result showed the ceramic-GEM has higher transmittance and less self-scattering especially for cold neutrons. One single ceramic GEM could give a gain of 10²-10⁴ in the mixture gas of Ar and CO₂ (90%:10%) and its energy resolution was about 27.7% by using ⁵⁵Fe X ray of 5.9 keV. A prototype has been developed in order to investigate the performances of the ceramic GEM-based neutron detector. Several neutron beam tests, including detection efficiency, spatial resolution, two-dimensional imaging, and wavelength spectrum, were carried out at CSNS and China Mianyang Research Reactor (CMRR). The results show that the ceramic GEM-based neutron detector is a good candidate to measure the high intensity neutrons.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1999년도 추계학술발표회요약집
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• pp.334-334
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• 1999

• Journal of Radiation Protection and Research
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• 제28권4호
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• pp.343-348
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• 2003

We have investigated in detail the operating properties of Gas Electron Multiplier (GEM) detectors with a double conical and a cylindrical structure in a wide range of external fields and GEM voltages. With the double conical GEM, the gain gradually increased with time by 10%; whereas this surface charging was eliminated with the cylindrical GEM. Effective gains above 1000 were easily observed over a wide range of collection field strengths in a gas mixture of $Ar/CO_2(70/30)$. The transparency and electron collection efficiency were found to depend on the ratio of external field and the applied GEM voltage; the mutual influence of both drift and collection fields was found to be trivial.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2004년도 학술대회지
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• pp.280-280
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• 2004

• Journal of Radiation Protection and Research
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• 제30권2호
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• pp.69-75
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• 2005

기체전자증폭기(GEM, gas electron multiplier)는 동박이 양면으로 도포된 절연기관에 미세구멍배열을 형성한 박막으로 기존의 기체형 방사선 검출기의 미약한 방사선 신호를 증폭하기 위해 널리 사용되어지고 있다. 미세구멍 내부에 강한 전기장을 형성함으로써 이 내부로 유입되는 전자에 충분한 에너지를 전달, 전자사태를 유도하는 원리를 이용한다. 따라서 GEM의 특성은 GEM을 포함한 방사선 검출기에 인가되는 전압 즉, 전기장의 분포에 의해 결정된다. 따라서 올바르지 못한 전기장의 분포에 대해서는 신호 전자가 수집전극으로 향하지 못하고, GEM의 상 하단의 전극으로 이동, 신호의 손실을 초래할 수도 있다. 본 논문에서는 GEM의 가장 중요한 성능 지표 중 하나인 1차 전자수집효율(primary electron collection efficiency)을 계산하였다. 방사선에 의해 발생된 전자는 전기력선을 따라서만 움직인다는 가정 하에, GEM의 단위 구조에 대해 표류전극에서의 전기력선의 수에 대한 수집전극에서의 전기력선의 수의 비로 전자수집효율을 계산하였다. 전기력선의 계산은 3차원 유한요소법을 이용하여 계산하였다. 본 논문에서 사용한 방법은 가장 이상적인 상황으로 국한되지만, GEM의 설계 및 최적 운전변수 도출에 유용하게 사용될 수 있을 것이다.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2007년도 공동학술대회 논문집
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• pp.219-224
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• 2007

We conducted geophysical surveys to detect antitank mine at Namji-eup, Gyeongsangnam-do which had been installed during Korean war. The surveys consisted of 2 stages, at the first stage we divided the survey area into 7 block and carried out magnetic gradient survey and GEM-3 EM survey sequentially for each block. Hence we verified anomaly areas using an excavator and a metal detector. Most of anomalies were found to be garbages such as trash cans, metallic wastes, and so on. And also, the concrete pipe was found at depth of 1 m, which had not referred in any report of that area. At the second stage, after trenching the covered soil down to 75 cm the same surveys were conducted. We could not find the strong signal to be inferred from a antitank mine, but we pointed out some anomalies to need careful handling because demining is very dangerous work even though there is few possibility that is mine.

• Nuclear Engineering and Technology
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• 제54권5호
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• pp.1754-1759
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• 2022

The activity of gamma-ray emitting nuclides is calculated assuming that each gamma-ray is detected individually; thus, the magnitude of the coincidence summing signal must be considered during activity calculations. Here, the correction factor for the coincidence summing effect was calculated, and the detection efficiencies of two HPGe detectors were compared. The CANBERRA Inc. GC4018 high-purity Ge detector provided an estimate for the peak-to-total ratio using a point source to determine the coincidence summing correction factor. The ORTEC Inc. GEM60 high-purity Ge detector uses EFFTRAN in LVis to obtain the parameters of the detector and source model and the gamma-gamma and gamma-X match estimates, in order to determine the coincidence summing correction factor. Nuclide analyses, radioactivity comparisons, and analyses of reference material samples were performed utilizing certified reference materials to accurately determine the detection efficiencies. For both Co-60 and Y-88, the detection efficiency for a point source increased by an average of at least 12-13%, whereas the detection efficiency determined using LVis increased by an average of at least 13-15%. The calculated radioactivity values of the certified reference material and reference material samples were accurate to within 3% and 6% of the measured values, respectively.

• Journal of Radiation Protection and Research
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• 제42권1호
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• pp.16-20
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• 2017

Background: The design of deuteron accelerator neutron source facilities requires reliable yield estimation of gamma-rays as well as neutrons from deuteron-induced reactions. We have so foar measured systematically double-differential thick target neutron yields (DDTTNYs) for carbon, aluminum, titanium, copper, niobium, and SUS304 targets. In the neutron data analysis, the events of gamma-rays taken simultaneously were treated as backgrounds. In the present work, we have re-analyzed the experimental data for a thick carbon target with particular attention to gamma-ray events. Materials and Methods: Double-differential thick target gamma-ray yields from carbon irradiated by 5 and 9 MeV deuterons were measured using an NE213 liquid organic scintillator at the Kyushu University Tandem accelerator Laboratory. The gamma-ray energy spectra were obtained by an unfolding method using FORIST code. The response functions of the NE213 detector were calculated by EGS5 incorporated in PHITS code. Results and Discussion: The measured gamma-ray spectra show some pronounced peaks corresponding to gamma-ray transitions between discrete levels in residual nuclei, and the measured angular distributions are almost isotropic for both the incident energies. Conclusion: PHITS calculations using INCL, GEM, and EBITEM models reproduce the spectral shapes and the angular distributions generally well, although they underestimate the absolute gamma-ray yields by about 20%.