• Vacuum Magazine
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• v.4 no.1
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• pp.12-15
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• 2017

The Pohang Accelerator Laboratory X-ray Free Electron Laser (PAL-XFEL) is a 0.1 nm hard X-ray FEL which aims at providing photon flux higher than $1{\times}10^{12}$ photons/pulse using a 10-GeV electron linac. The vacuum system of the machine consists of an injector section including an S-band photocathode RF gun, 10-GeV electron linac section based on S-band normal conducting accelerating structures and a 150-m long out-vacuum undulator system. We introduce the present status of PAL-XFEL vacuum systems.

• Journal of Radiation Protection and Research
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• v.26 no.3
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• pp.327-331
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• 2001

The Pohang Neutron Facility based on an electron linac was constructed in order to construct the infrastructure for nuclear data production in Korea. It consists of a 100-MeV electron linac, a water-cooled Ta target, and an 11-m time-of-flight path. We measured the time-of-flight path length, the neutron energy spectra for different water levels inside the moderator, and the neutron total cross sections of polyethylene and copper by the transmission method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.3
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• pp.1035-1039
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• 2010

Activation products generated by photoneutrons in concrete shielding wall around electron linac were estimated for a high energy X-ray container cargo inspection system. Monte carlo code, MCNPX2.5.0 was used for reference system of 9MeV fixed type dual-direction container cargo inspection system installed at major harbors in Korea. Activation products inventory generated by photoneutron (n,$\gamma$) reaction are estimated, and then radiation dose rate is calculated from the results.

• Nuclear Engineering and Technology
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• v.55 no.10
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• pp.3591-3598
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• 2023

Photoneutron background spectroscopy observations at linac are essential for directing accelerator shielding and subtracting background signals. Therefore, we constructed a Bonner Sphere Spectrometer (BSS) system based on an array of BF₃ gas proportional counter tubes. Initially, the response of the BSS system was simulated using the MCNP5 code. Next, the response of the system was calibrated by using neutrons with energies of 2.86 MeV and 14.84 MeV. Then, the system was employed to measure the spectrum of the ²⁴¹Am-Be neutron source, and the results were unfolded by using the Gravel and EM algorithms. Using the validated system, the undesirable neutron spectrum of the 120 MeV electron linac was finally measured and acquired. In addition, it is demonstrated that the equivalent undesirable neutron dose at a distance of 3.2 m from the linac is 19.7 mSv/h. The results measured by the above methods could provide guidance for linac-related research.

• Journal of Radiation Protection and Research
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• v.26 no.3
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• pp.333-335
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• 2001

The 2 GeV electron linac, the injector of the Pohang Light Source, was used as a photo-neutron source for radiation shielding research. The operational beam parameters are the nominal electron intensity of $0.5\;{\sim}5\;nC/sec$, the repetition rate of 10 Hz, and the beam pulse length of 1.0 nsec. One electron beam line was modified in order to install the target systems for producing pulsed photo-neutrons. The neutron spectrum and intensity were investigated by the time-of-flight technique. The reliable maximum energy of the measured neutrons was about 500 MeV. The number of neutrons above 20 MeV produced by one 1 GeV electron in a thick Pb target was about $6.45{\times}10^{-4}/sr$ at 90 degrees to the beam axis. The status of the photo-neutron source and the application research are presented.

• Progress in Medical Physics
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• v.28 no.2
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• pp.49-53
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• 2017

The energy distribution was calculated for an electron beam from an electron linear accelerator developed for medical applications using computational methods. The depth dose data for monoenergetic electrons from 0.1 MeV to 8.0 MeV were calculated by the DOSXYZ/nrc code. The calculated data were used to generate the energy distribution from the measured depth dose data by numerical iterations. The measured data in a previous work and an in-house computer program were used for the generation of energy distribution. As results, the mean energy and most probable energy of the energy distribution were 5.7 MeV and 6.2 MeV, respectively. These two values agreed with those determined by the IAEA dosimetry protocol using the measured depth dose.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.110.2-110.2
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• 2016

4세대 방사광가속기는 0.1nm급 X-선 자유전자레이저(X-ray Free Electron Laser : XFEL) 광원을 빔라인 사용자들에게 제공하기 위하여 2011년 건설을 시작하였고, 2015년부터 장치를 설치하기 시작했으며 현재 건설 완료단계에 이르러 있다. 이 장치에서 진공시스템은 10-11 mbar의 초고진공이 요구되는 전자빔 발생장치인 RF Gun을 포함하는 입사장치구간(Injector)과 전체길이 800 m에 이르는 전자빔을 가속시키는 선형가속기구간(Linac) 그리고 결맞음 방사광을 발생시키는 언듈레이터구간으로 나눌 수 있다. 본 논문에서는 각 구간별 진공시스템에 대한 건설 현황에 대하여 보고하고자 한다.

• Progress in Medical Physics
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• v.27 no.1
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• pp.25-30
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• 2016

The dosimetric characteristics were experimentally evaluated for electron beams from the prototype linac developed for radiotherapy units. This paper focuses on the electron beam output and energy variations as a function of electron gun heater current. The electron energy was derived from its mean and most probable energies measured by film dosimetry. The electron beam output at the maximum electron energy was measured with the plane parallel ionization chamber in water using TRS-398 dosimetry protocol. The mean energy and the most probable energy of the electron beam were 6.54~3.31 MeV and 5.94~2.80 MeV at electron gun current of 2.02~2.50 A respectively. The output dose rate for an electron beam of mean energy 6.54 MeV was 5.41 Gy/min ${\pm}1.5%$ at the reference depth in water.

• Progress in Medical Physics
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• v.26 no.1
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• pp.1-5
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• 2015

The C-band compact linear accelerator (linac) is being developed at Dongnam Institute of radiological & Medical Sciences (DIRAMS) for medical and industrial applications. This paper was focused on the output measurement of the electron beam generated from the prototype electron linac. The dose rate was measured in unit of cGy/min per unit pulse frequency according to the IAEA TRS-398 protocol. Exradin-A10 Markus type plane parallel chamber used for the measurement was calibrated in terms of dose to water at the reference depth in water. The beam quality index ($R_{50}$) was determined by the radiochromic film with a solid water phantom approximately due to low energy electrons. As a result, the determined electron beam output was $17.0cGy/(min{\cdot}Hz$. The results were used to monitor the accelerator performance during the development procedure.

• Journal of Radiation Protection and Research
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• v.26 no.3
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• pp.133-137
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• 2001

Spatial and time distributions of x-rays and neutrons from Hokkaido University 45 MeV electron linac facility were measured and compared with the calculation. In the calculation, x-rays in a Pb-target were evaluated using the EGS-code. The x-rays and the neutrons from the target to the facility building boundary and skyshine process outside the facility building were simulated with the EGS and the MCNP respectively.