• Nuclear Engineering and Technology
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• 제19권2호
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• pp.115-121
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• 1987

SNU 1.5MV 직렬형 반데그라프 가속기의 고전압 안정화 계통을 설치하여 그 동작 특성을 파악하고 최적화하였다. 이온빔 수송계통의 최적 운전 조건을 단계적인 실험을 통하여 결정하였으며 적절한 운전 조건하에 표적함에서 350nA의 가속된 양성자빔을 얻었다. 고전압을 안정화하지 않았을 때의 고전압 변동은 이온빔을 가속하지 않을 때와 가속할 때 각각 $\Delta$V/V=5.2$\times$$10^{-3}$, 7.2$\times$$10^{-3}$이었으며 그 변동 주파수는 3Hz 이하였다. 터미날 전압 247.3kV에서 고전압 안정화 계통의 최적 운전을 통하여 터미날 전압의 변동은 $\Delta$V/V=2.45$\times$$10^{-4}$ 으로 줄었고 에너지 안정도는 $\Delta$E/E=2.44$\times$$10^{-4}$ 으로 유지되었으며 이 때의 안정화 계수는 29.4였다.

• 한국진공학회지
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• 제2권4호
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• pp.416-423
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• 1993

Hydrogen depth profiling was performed by H(19F, $\alpha$${\gamma}$) nuclear resonance reactin . A cesium sputtering ion sorce and 1.7MV Tandem Van de Graaff accelerator was used for the production of 6.5MeV 19F ion. The ${\gamma}$ rays produced by the reaction were measure dby 3" $\times$3" and 6" $\times$8" Nal detectors . A test measurement was done for hydrogen contaminatin layer of a bare silicon wafer, Si3N4(H) and Zr(O)a-Si/Si for the purpose of verifying the applicability , detection limit and the reliability of the method.ility of the method.

• 한국전기전자재료학회논문지
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• 제17권12호
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• pp.1264-1270
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• 2004

A fast switching thyristor with a superior trade-off property between the on-state voltage drop and the turn-off time could be fabricated by the proton irradiation method. After making symmetric thyristor dies with a voltage rating of 1,600 V from 350 $\mu$m thickness of 60 $\Omega$ㆍcm NTD-Si wafer and 200 $\mu$m width of n-base drift layer, the local carrier lifetime control by the proton irradiation was performed with help of the HI-13 tandem accelerator in China. The thyristor samples irradiated with 4.7 MeV proton beam showed a superior trade-off relationship of $V_{TM}$ = 1.55 V and $t_{q}$ = 15 $\mu$s attributed to a very narrow layer of short carrier lifetime(～1 $\mu$s) in the middle of its n-base drift region. To explain the small increase of $V_{TM}$ , we will introduce the effect of carrier compensation at the low carrier lifetime region by the diffusion current.ffusion current.t.

• Journal of Radiation Protection and Research
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• 제37권2호
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• pp.70-74
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• 2012

Silicon carbide (SiC) is a promising material for neutron detection at harsh environments because of its capability to withstand strong radiation fields and high temperatures. Two PIN-type SiC semiconductor neutron detectors, which can be used for nuclear power plant (NPP) applications, such as in-core reactor neutron flux monitoring and measurement, were designed and fabricated. As a preliminary test, MCNPX simulations were performed to estimate reaction probabilities with respect to neutron energies. In the experiment, I-V curves were measured to confirm the diode characteristic of the detectors, and pulse height spectra were measured for neutron responses by using a $^{252}Cf$ neutron source at KRISS (Korea Research Institute of Standards and Science), and a Tandem accelerator at KIGAM (Korea Institute of Geoscience and Mineral Resources). The neutron counts of the detector were linearly increased as the incident neutron flux got larger.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.1
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• pp.271-275
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• 2004

A fast switching thyristor with a superior trade-off property between the on-state voltage drop and the turn-off time could be fabricated by the proton irradiation method. After fabricating symmetric thyristor dies with a voltage rating of 1,600V from $350{\mu}m$ thickness of $60{\Omega}cm$ NTD-Si wafer and $200{\mu}m$ width of N-base drift layer, the local carrier lifetime control by the proton irradiation was performed with help of the HI-13 tandem accelerator in China. The thyristor samples irradiated with 4.7MeV proton beam showed a superior trade-off relationship of $V_{TM}=1.55V\;and\;t_q=15{\mu}s$ attributed to a very narrow layer of short carrier lifetime(${\sim}1{\mu}s$) in the middle of its N-base drift region. To explain the small increase of $V_{TM}$, we will introduce the effect of carrier compensation by the diffusion current at the low carrier lifetime region.

• Nuclear Engineering and Technology
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• 제22권2호
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• pp.108-115
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• 1990

0.5~l.2-MeV 양성자빔에 대한 X-선 발생단면적의 측정을 Cu와 Au에 대해 수행하였다. 이 실험에서는 SNU 1.5-MV 탄뎀 반데그라프 가속기에서 얻은 양성자빔을 표적에 입사시켰다. 여기서 방출된 X-선과 후방산란된 양성자는 Si(Li) X-선 검출기와 SSB(Silicone Surface Barrier) 하전입자 검출기를 이용해 동시 측정하였다. 그리하여 측정된 X-선 발생단면적은 다른 실험치들 및 PWBA(Plane Wave Born Approximation)와 ECPSSR(Perturbed Stationary State corrected Energy loss, Coulomb deflection, Relativistic effects)인 이론치들과 비교하였다. 1.0-MeV근처의 양성자에너지에 대해 측정치는 PWBA 값보다는 ECPSSR(D.D. Cohen et al., 1985) 값에 더 잘 일치함을 보였다. 특히, Au의 측정치는 1.2-MeV 양성자빔에 대해 9.69$\pm$0.39 bams이었고, ECPSSR 이론치와는 5% 이내로 일치했으며, 0.5~l.2-MeV 양성자에 대한 실험치는 대부분의 다른 실험치들과 30% 이내로 일치했다.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.267-268
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• 2002

Microbeam is a new avenue of radiation research especially in radiation biology and radiation protection. Selective irradiation of an ionizing particle to a targeted cell organelle may disclose such mechanisms as signal transaction among cell organelles and cell-to-cell communication in the processes toward an endpoint observed. Bystander effect, existence of which is clearly evidenced by application of the particle microbeam to biological experiments, suggests potential underestimation in the conventional risk estimation at low particle fluence rates, such as environment of space radiations in ISS (International Space Station). To promote these studies we started the construction of our microbeam facility (named as SPICE) to our HVEE Tandem accelerator (3.4 MeV proton and 5.1 MeV $^4$He$\^$2+/). For our primary goal, "irradiation of single particle to cell organelle within a position resolution of 2 micrometer in a reasonable irradiation time", special features are considered. Usage of a triplet Q magnet for focussing the beam to submicron of size is an outstanding feature compared to facilities of other institutes. Followings are other features: precise position control of cell dish holder, design of the cell dish, data acquisition of microscopic image of a cell organelle (cell nucleus) and data processing, a reliable particle detection, soft and hard wares to integrate all these related data, to control and irradiate exactly determined number of particles to a targeted spot.

• Nuclear Engineering and Technology
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• 제23권4호
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• pp.420-425
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• 1991

SNU 1.5-MV 직렬형 반데그라프 가속기의 헬륨음이온원으로서 Rb 전하교환기를 제작하였다. 교환기의 최적운전조건을 결정하기 위해 특성실험을 수행하였다. Duoplasmatron 이온원에서 인출된 1~10 keV 에너지의 첼륨양이온빔을 Rb 증기속에 통과시킴으로써 2 단계 전하교환반응, 즉 $He^{+}\;+\;Rb\;{\rightarrow}\;He^{\circ\ast}\;+\;Rb^{+}\;과\;He^{\circ\ast}\;+\;Rb\;{\rightarrow}\;He^{-}\;+\;Rb^{+}$에 의해 헬륨음이온을 얻었다 실험결과로부터 헬륨음이온의 최대생성률이 헬륨양이온에너지가 7 keV일때 얻어짐을 알 수 있었다. Oven과 Canal의 최적온도는 각각 $370^{\circ}C{\;}와\;95^{\circ}C$로 결정되었다. 최적동작조건하에서 최대 헬륨음이온 생성률은 $2.42\pm002\;%$이었다. 본 전하교환기는 헬륨음이온생성에 효과적인 장치임이 입증되었다.

• Nuclear Engineering and Technology
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• 제51권5호
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• pp.1444-1450
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• 2019

The fast-neutron shielding behaviour (FNSB) of two clay-materials (Ball clay and Kaolin)of Southwestern Nigeria ($7.49^{\circ}N$, $4.55^{\circ}E$) have been investigated using effective removal cross section, ${\Sigma}_R(cm^{-1})$, mass removal cross section, ${\Sigma}_{R/{\rho}}(cm^2g^{-1})$ and Mean free path, ${\lambda}$ (cm). These parameters decide neutron shielding behaviour of any material. A computer program - WinNC-Toolkit has been used for computation of these parameters. The toolkit evaluates these parameters by using elemental compositions and densities of samples. The proficiency of WinNC-Toolkit code was probe by using MCNPX and GEANT4 to model fast neutron transmission of the samples under narrow beam geometry, intending to represent the actual experimental setup. Direct calculation of effective removal cross section ($cm^{-1}$) of the samples was also carried out. The results from each of the methods for each types of the studied clay-materials (Ball clay and Kaolin) shows similar trend. The trend might be the fingerprint of water content retained in each of the samples being baked at different temperature. The compositions of each sample have been obtained by Particle-Induced X-ray Emission (PIXE) technique (Tandem Pelletron Accelerator: 1.7 MV, Model 5SDH). The FNSB of the selected clay-materials have been compared with standard concrete. The cognizance of various factors such as availability, thermo-chemical stability and water retaining ability by the clay-samples can be analyzed for efficacy of the material for their FNSB.

• 한국진공학회지
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• 제10권3호
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• pp.380-386
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• 2001

정밀가변슬릿과 자기사중극렌즈로 구성된 핵 마이크로프로브 (nuclear microprobe) 시스템을 일차행렬법을 이용한 빔광학 전산모사를 통해 설계하였으며, 제작된 시스템을 KIGAM 1.7 MV 탄뎀 반데그라프 가속기의 $30^{\circ}$ 빔라인에 설치하였다. X 및 Y축에 대한 역배율은 각각 25와 4.9로 계산되며, 3 MeV 양성자빔의 경우 최소 빔크기는 약 5 미크론, 빔전류는 약 1 nA 정도로 추산된다. PIXE, RBS, ERDA등 MeV 이온빔분석법과 이온빔 미세가공을 위해 다목적 8각형 표적함을 제작하였으며, 표적함은 X-선 및 하전입자검출기, 줌현미경, 파라데이컵, 4축 시료이송계 및 고진공계로 구성되어 있다. 현재 핵 마이크로프로브 시스템 성능 조사가 이루어지고 있으며, 자동화된 시료 이송 및 자료 처리 시스템이 설치되면 일상적인 마이크로 이온빔 분석이 가능해 질 것으로 예상된다.