• 한국콘텐츠학회논문지
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• 제4권2호
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• pp.76-82
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• 2004

기존의 $^{141}$Pr(n,$\gamma$)$^{142}$Pr 반응에 대한 열중성자포획단면적 결과들은 여러 종류의 값들이 보고 되어 있다. 본 연구에서는 이상적인 중성자속을 가지는 교토원자로실험소의 중수열중성자장치를 이용하여 방사화 방법을 통해 열중성지포획 단면적을 보다 정밀하게 측정하였다. 시료에 입사되는 열 중성자속은 $^{197}$Au(n,${\gamma}$)$^{198}$Au 반응을 통하여 측정되었다. 측정된 결과는 기존의 측정 결과 및 JENDL-3.2, ENDF/ B-VI, JEF-2.2의 평가치들과 비교하였다.

• Nuclear Engineering and Technology
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• 제34권6호
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• pp.533-544
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• 2002

The neutron induced nuclear data for Mo-95, Tc-99, Ru-101 and Rh-103 was calculated and evaluated in the fast energy region. The energy dependent optical model potential parameters were extracted based on the recent experimental data and applied up to 20 MeV. The s-wave strength function was calculated from the parameters. Spherical optical model, statistical model in equilibrium energy, multistep direct and multistep compound model in pre-equilibrium energy and direct capture model were used in the calculation. The theoretically calculated cross sections were compared with the experimental data and the evaluated files The model- calculated total and capture cross sections were in good agreement with the reference experimental data. The direct capture contribution improved the capture cross sections in pre- equilibrium region. The evaluated cross section results were compiled to ENDF-6 format and will improve the ENDF/B-Vl.

• Nuclear Engineering and Technology
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• 제52권9호
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• pp.2072-2077
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• 2020

The purpose of this study was to demonstrate the feasibility of sensing changes in a tumor during boron neutron capture therapy (BNCT) using a Monte Carlo simulation tool. In the simulation, an epi-thermal neutron source and a water phantom including boron uptake regions (BURs) were simulated. Moreover, this simulation also included a detector for positron emission tomography (PET) scanning and an adaptively-designed collimator (ADC) for PET. After the PET scanning of the water phantom, including the 511 keV source in the BUR, the ADC was positioned in the PET's gantry. Single prompt gamma rays were collected through the ADC during neutron irradiation. Then, single prompt gamma ray-based tomography images of different sized tumors were acquired by a four-step process. Both the signal-to-noise ratio (SNR) and tumor size were analyzed from each step image. From this analysis, we identified a decreasing trend of both the SNR and signal intensity as the tumor size decreased, which was confirmed in all images. In conclusion, we confirmed the feasibility of sensing changes in a tumor during BNCT using PET and an ADC through Monte Carlo simulation.

• 한국방사선학회논문지
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• 제8권6호
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• pp.287-292
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• 2014

본 연구는 자연 속에 미량(존재비: 0.012 %)으로 존재하는 $^{180}Ta$의 중성자포획 공명에 대하여 포획단면적의 계산치와 측정치를 비교하여 분석하였다. 일반적으로 중성자 공명은 Breit-Wigner식으로 정의되며, 식에는 공명에너지를 중심으로 공명의 폭을 결정하는 다양한 인자들로 구성되어 있다. 그러나 $^{180}Ta$의 경우 중성자포획단면적과 공명에 대한 정보가 잘 알려져 있지 않고 실험적으로도 측정되어진 예가 현재까지는 없는 것이 현실이다. 따라서 본 실험에서는 천연 Ta속에 포함되어진 $^{180}Ta$에 의한 중성자 포획에 의해 발생되는 감마선을 관측하여 $^{180}Ta$의 공명을 분석하고 Mughabghab에 의해서 계산되어진 공명인자를 사용하여 1 eV이하의 에너지에 대한 중성자포획단면적을 계산하고 비교분석하였다. 측정을 위해서 교토대학원자로 실험소의 46-MeV 전자선형가속기를 이용하여 중성자 TOF 방법으로, 에너지 영역 0.003 eV에서 10 eV에 걸쳐 측정하였다. 측정을 위해서는 12개의 $Bi_4Ge_3O_{12}(BGO)$섬광체로 구성된 전에너지 흡수검출장치로 $^{180}Ta(n,{\gamma})^{181}Ta$ 반응으로부터 나오는 즉발감마선을 측정하였다.

• 지구물리와물리탐사
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• 제18권3호
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• pp.154-161
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• 2015

본 연구에서는 중성자-감마 스펙트럼검층 존데 설계를 목적으로 Monte Carlo 시물레이션을 이용하여 열중성자 반응의 우세한 영역 파악 및 포획감마 스펙트럼의 에너지피크 값에 기초한 지층 구성 원소 구분을 수행하였다. 14 MeV 에너지준위의 중성자를 방출하는 중성자발생장치를 선원으로 이용하여 선원으로부터 10 cm 간격으로 12개의 중성자 검출기들을 배열함으로써 거리에 따른 열중성자 양을 측정하였다. 시추공 영향 저감을 위해 존데모형에 차폐재를 적용하여 보다 정확한 열중성자 측정을 수행하여 열중성자 반응이 우세한 위치를 분석한 뒤, 이 위치에서 검출된 포획감마 에너지 스펙트럼을 분석하여 지층을 구성하는 주요 원소 및 그 양을 확인하였다. 본 연구 결과는 중성자-감마 스펙트럼검층 존데의 신호대잡음 비 향상과 포획감마 검출기 최적 위치 선정에 도움이 될 것으로 판단된다.

• Nuclear Engineering and Technology
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• 제38권8호
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• pp.803-808
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• 2006

The neutron induced nuclear cross section data for Ir-191 and Ir-193 were calculated and evaluated from unresolved resonance energy to 20MeV. The energy-dependent optical model potential parameters were determined based on the experimental data and applied up to 20MeV. A spherical optical model, a statistical model in an equilibrium energy region, and a multistep direct and multistep compound model in a pre-equilibrium energy region were used in the calculations. The direct capture model enhanced the fast neutron capture in the pre-equilibrium energy. The theoretically calculated cross sections were compared with the experimental data and the evaluated files. The calculations were found to be in good agreement with the experiment data. The evaluated cross section results were compiled with the ENDF-6 format. The fast energy results will be merged with the resonance parts to create a full evaluation library. The improvement of the neutron-induced cross section data will contribute to an increase in the efficiency of the production of Ir-192 as a radiation source.

• Nuclear Engineering and Technology
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• 제49권1호
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• pp.189-195
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• 2017

Gel dosimeters have unique advantages in comparison with other dosimeters. Until now, these gels have been used in different radiotherapy techniques as a reliable dosimetric tool. Because dose distribution measurement is an important factor for appropriate treatment planning in different radiotherapy techniques, in this study, we evaluated the ability of the N-isopropylacrylamide (NIPAM) polymer gel to record the dose distribution resulting from the mixed neutron-gamma field of boron neutron capture therapy (BNCT). In this regard, a head phantom containing NIPAM gel was irradiated using the Tehran Research Reactor BNCT beam line, and then by a magnetic resonance scanner. Eventually, the $R_2$ maps were obtained in different slices of the phantom by analyzing T2-weighted images. The results show that NIPAM gel has a suitable potential for recording three-dimensional dose distribution in mixed neutron-gamma field dosimetry.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1997년도 춘계학술발표회논문집(2)
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• pp.427-432
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• 1997

Boron neutron capture therapy(BNCT) is a binary treatment modality that can selectively irradiate tumor tissue. More is known now about the radiation biology of BNCT, which has reemerged as a potentially useful method for preferential irradiation of tumors. We design a square reactor (that can easily be reconfigured into polygonal reactors as the need arises) with four slab type assemblies to produce high quality epithermal neutron beans and thermal neutron beams jot use in neutron capture therapy. With a low operating power of 300kW, the heat generated in the core can be removed by natural convection through a pool of tight water. The proposed design in this study could be constructed for a dedicated clinical BNCT facility that would operate very safely.

• 분석과학
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• 제5권1호
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• pp.57-61
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• 1992

중성자 스펙트럼을 측정하기 위해 $^6Li$ 중성자 분광계를 설치하고 $^{137}Cs$과 $^{207}Bi$ 점선원을 사용하여 $^6Li$ 검출관의 특성을 파악하고 $^{241}Am-Be$ 중성자 선원을 사용하여 중성자 포획피이크를 측정하였으며, $^6Li$ (n, ${\alpha}$) T 반응에 의한 에너지 파고스펙트럼을 측정하였다. 또한 중성자 선원의 조사 시간의 변화, 선원과 검출관 사이의 거리의 변화, 파고분석기의 문턱조절자를 미세하게 변환시키는 경우에 파고스펙트럼을 측정하였다.

• Nuclear Engineering and Technology
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• 제35권1호
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• pp.35-44
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• 2003

The neutron induced nuclear data for Eu-153, Gd-155 and Cd-157 are calculated and evaluated in the high energy region. The evaluation procedure for deformed nuclei is setup by using Ecis-Empire codes. The energy dependent optical model potential parameters are searched based on the recent experimental data and applied up to 20 MeV. Optical model, full featured Hauser-Feshbach model and multistep direct and multistep compound model are used in the calculation. The direct-semidirect capture model and the direct coupled-channels contribution to discrete levels are introduced to improve the capture and inelastic scattering cross sections. The theoretically calculated cross sections are compared with the experimental data and the evaluated files. The model-calculated total and capture cross sections are in good agreement with the reference experimental data. The evaluated cross section results are compiled to ENDF-6 format and are expected to improve the ENDF/B-Vl.