• Journal of Radiation Protection and Research
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• 제26권3호
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• pp.287-290
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• 2001

The 9.17MeV gamma-rays from the $^{13}C(p,\;{\gamma})^{14}N,\;^{14}N({\gamma},\;{\gamma})^{14}N$ reactions were measured. The incident 9.17MeV gamma-ray was produced from the $^{13}C(p,\;{\gamma})^{14}N$ reaction at Ep=1.75MeV resonance. The 1.75MeV proton beam was accelerated using the 3MV SNU-AMS Tandetron and 1.7MV KIGAM Tandem accelerators. The enriched 13C target was $121{\mu}g/cm^2$ self-supporting foil, and we used liquid nitrogen as a resonant absorption target. We used a HP-Ge detector with 30% efficiency and less 2keV energy resolution. We developed new method to detect the scattered 9.17MeV gamma-ray from the nitrogen target by using the energy difference between the Doppler shifted gamma-ray from the $^{13}C(p,\;{\gamma})^{14}N$ reaction and the resonant absorbed and rescattered gamma-ray from the $^{14}N({\gamma},\;{\gamma})^{14}N$ reaction.

• 한국응용곤충학회지
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• 제33권4호
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• pp.263-269
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• 1994

궐련벌레(Lasioderma serricorne F)가 제품담배내 오염되었을때의 방제방법으로 감마선 이용법을 선전 방제효과를 조사하였다. Gelatin capsules에 공시충을 넣은 다음 감마선을 조사해 본 결과 0.8kGy이상의 선량에서 난태는 모두 살충되었고 용태나 성충때 및 유충태는 0~30%가 살충되었다. 몇가지 제품담배값내에 공시충을 함유한 gelatin capsules이 삽입된 궐련을 넣은후 감마선 조사시의 궐련벌레 충태별 방제효과도 동일한 결과를 얻었다. 감마선의 영향을 받은 궐련벌레의 성충 및 유충태를 인공먹이로 사육해 본 결과 차세대 개체군 증식이 확인되지 않았다. 감마선에 노출된 궐련벌레의 각 충태는 선량이 높아질수록 생존기간이 짧아졌으며 4령 유충이 처리 공시충중 가장 오래 생존하였다. 감마선에 노출된 제품담배의 고유향기나 맛은 선량 증가에도 영향을 받지 않았다. 감마선이 처리된 제품담배의 포갑지나 궐련지 및 은박지 등은 고유의 색도 또한 변화하지 않았다.

• Journal of Radiation Protection and Research
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• 제47권4호
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• pp.214-225
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• 2022

Background: The conventional cerium-doped Gd₂Al₂Ga₃O₁₂ (GAGG(Ce)) scintillator-based gamma-ray imager has a bulky detector, which can lead to incorrect positioning of the gammaray source if the shielding against background radiation is not appropriately designed. In addition, portability is important in complex environments such as inside nuclear power plants, yet existing gamma-ray imager based on a tungsten mask tends to be weighty and therefore difficult to handle. Motivated by the need to develop a system that is not sensitive to background radiation and is portable, we changed the material of the scintillator and the coded aperture. Materials and Methods: The existing GAGG(Ce) was replaced with Bi₄Ge₃O₁₂ (BGO), a scintillator with high gamma-ray detection efficiency but low energy resolution, and replaced the tungsten (W) used in the existing coded aperture with lead (Pb). Each BGO scintillator is pixelated with 144 elements (12 × 12), and each pixel has an area of 4 mm × 4 mm and the scintillator thickness ranges from 5 to 20 mm (5, 10, and 20 mm). A coded aperture consisting of Pb with a thickness of 20 mm was applied to the BGO scintillators of all thicknesses. Results and Discussion: Spectroscopic characterization, imaging performance, and image quality evaluation revealed the 10 mm-thick BGO scintillators enabled the portable gamma-ray imager to deliver optimal performance. Although its performance is slightly inferior to that of existing GAGG(Ce)-based gamma-ray imager, the results confirmed that the manufacturing cost and the system's overall weight can be reduced. Conclusion: Despite the spectral characteristics, imaging system performance, and image quality is slightly lower than that of GAGG(Ce), the results show that BGO scintillators are preferable for gamma-ray imaging systems in terms of cost and ease of deployment, and the proposed design is well worth applying to systems intended for use in areas that do not require high precision.

• 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%.

• Natural Product Sciences
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• 제19권2호
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• pp.127-136
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• 2013

Ionizing radiation, including that evoked by gamma (${\gamma}$)-rays, induces oxidative stress through the generation of reactive oxygen species, resulting in apoptosis, or programmed cell death. This study aimed to elucidate the radioprotective effects of hyperoside (quercetin-3-O-galactoside) against ${\gamma}$-ray radiation-induced apoptosis in Chinese hamster lung fibroblasts, V79-4 and demonstrated that the compound reduced levels of intracellular reactive oxygen species in ${\gamma}$-ray-irradiated cells. Hyperoside also protected irradiated cells against DNA damage (evidenced by pronounced DNA tails and elevated phospho-histone H2AX and 8-oxoguanine content) and membrane lipid peroxidation. Furthermore, hyperoside prevented the ${\gamma}$-ray-provoked reduction in cell viability via the inhibition of apoptosis through the increased levels of Bcl-2, the decreased levels of Bax and cytosolic cytochrome c, and the decrease of the active caspase 9 and caspase 3 expression. Taken together, these results suggest that hyperoside defend cells against ${\gamma}$-ray radiation-induced apoptosis by inhibiting oxidative stress.

• Nuclear Engineering and Technology
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• 제54권9호
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• pp.3398-3402
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• 2022

We fabricated a 15 m long position-sensitive plastic scintillation optical fiber (PSOF) detector consisting of a PSOF, two photomultiplier tubes, four fast amplifiers, and a digitizer. A single PSOF was used as a sensing part to estimate the gamma-ray source position, and ¹³⁷Cs, an uncollimated solid-disk-type radioactive isotope, was used as a gamma-ray emitter. To improve the sensitivity, accuracy, and measurement time of a PSOF detector compared to those of previous studies, the performance of the amplifier was optimized, and the digital signal processing (DSP) was newly designed in this study. Moreover, we could measure very low dose rates of gamma-rays with high sensitivity and accuracy in a very short time using our proposed PSOF detector. The results of this study indicate that it is possible to accurately and quickly locate the position of a very low dose rate gamma-ray source in a wide range of contaminated areas using the proposed position-sensitive PSOF detector.

• 식물조직배양학회지
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• 제27권2호
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• pp.143-148
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• 2000

감 돌연변이 획득을 위해 기내배양 신초에 ${\gamma}$-선을 조사하여 변이유기를 위한 적정 선량, ${\gamma}$-선 조사 식물체의 기내 발근 및 생육 특성을 조사한 결과는 다음과 같다. 감 돌연변이 유기를 위한 적정한 조사 선량 (LD$_{50}$)은 서촌조생 품종에서 1 krad와 2 krad사이이었고, 일목계차랑 품종은 1 krad이었다. ${\gamma}$-선을 조사한 신초를 1차,2차, 3차에 걸쳐 계대배양하는 각 기간의 기내 생육상태를 보면 ${\gamma}$-선량이 증가할수록 기내에서 생장한 신초의 길이가 감소하였으며, 신초의 정아가 가장 장애를 많이 받았다. 서촌조생 품종에서 신초의 37.5~58.3% 정도가 발근되었고 발근율은 2 krad 처리에서는 가장 낮았다. ${\gamma}$-선 조사선량이 높아지면 발근율과 뿌리의 발생수가 줄어들었다. 순화한 뒤 6주 동안 생장상에서 생육한 ${\gamma}$-선 조사 개체는 무처리 개체의 묘고가 6.0 cm인데 비해 2krad 처리개체는 평균 묘고는 2.6 cm에 불과하였다. 또한 발생한 가지의 수도 무처리에서는 1.0개인데 비해 2krad에서는 1.8 개로 많았다. 온실 생육시에서 ${\gamma}$-선 처리선량이 높았던 개체는 처리되지 않았거나 낮았던 개체에 비해 묘고가 작고 분지수가 많았으며, 생육상태도 부진하여 생육 중에 33%정도만 생존하고 나머지는 고사하였다.다.

• 천문학논총
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• 제30권2호
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• pp.553-557
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• 2015

This review summarises the current status of the Galactic TeV ($10^{12}$ eV) gamma-ray source population. It also briefly looks at the future beyond the current generation of TeV gamma-ray facilities, and highlights the role of the interstellar medium (ISM) in helping to resolve some of the challenges in interpreting the wealth of results which have been found in recent years.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2016년도 추계학술대회
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• pp.944-945
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• 2016

감마선 영상화 장치에서 감마선을 탐지하는 검출부는 선원을 바라보는 Collimator와 Collimator 이외의 방향에서 입사되는 감마선을 차폐하기 위한 차폐체로 구성되며 검출센서는 해당 차폐체 내부에 위치하게 된다. 감마선에 대한 분포는 Collimator의 입사구를 통해 들어오는 신호와 검출부가 바라보는 방향에 대한 정보를 통해 분포를 나타낼 수 있다. 때문에 입사구에서 들어오는 신호 외에는 잡음으로 처리해야 하므로 차폐체의 역할이 중요하다. 본 논문에서는 상용 감마선 탐지장치의 보다 축소된 납 기반의 콜리메이터 및 차폐체에 대하여 구조와 물성을 변경하여 소형, 경량화 된 Collimator 및 차폐체를 제작하였다. 또한 감마선 조사시험시설을 이용하여 감마선 입사구의 측정된 신호값을 기준으로 차폐 효율을 분석하였다. 분석결과 제작된 Collimator 및 차폐체가 영상화 장치구현를 구현하는데 보다 효율적임을 확인하였다.

• Journal of Plant Biology
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• 제7권3호
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• pp.9-14
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• 1964

The sensitivities of Chlorella ellipsoidea to ${\gamma}$-ray from Cobalt-60 were determined by measuring the photosynthetic and respiratory activities and the changes in phosphate contents in various fractions of the irradited cells, which were further grown in a standard medium after irradiation, were compared to those of non-irradiated normal cells. The photosynthetic and repiratory activities of the cells were almost inversely proportional to the dose of ${\gamma}$-ray irradiated and the photosynthetic activity was more sensitive than the respiratory activity of the cells. The most sensitive to ${\gamma}$-ray was growth activity, followed by photosynthesis, exogenous and endogenous respirations of the cells in decreasing order. Chlorella cells were so resistant to ${\gamma}$-ray comapred with other organisms that about 280,000 r dose of ${\gamma}$-ray irradiaton was necessary to reduce as much as half the subsequent photosynthetic activity. When the irradiated algae were further cultured in a standard medium, the phosphate contents in the fraction of DNA, RNA and phosphoprotein decreased considerably compared with those of non-irradiated normal cells, while the phosphate contents in the fraction of polyphosphates increased than those of control. Therefore, it was deduced that ${\gamma}$-ray inhibited the synthesis of DNA from polyphosphates, that the growth of Chlorella cells were consequently retarded.