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Jang, Kyoung Won,Yagi, Takahiro,Pyeon, Cheol Ho,Yoo, Wook Jae,Shin, Sang Hun,Jeong, Chiyoung,Min, Byung Jun,Shin, Dongho,Misawa, Tsuyoshi,Lee, Bongsoo SPIE--the International Society for Optical Engine 2013 Journal of biomedical optics Vol.18 No.2
<P>A Cerenkov fiber-optic dosimeter (CFOD) is fabricated using plastic optical fibers to measure Cerenkov radiation induced by a therapeutic photon beam. We measured the Cerenkov radiation generated in optical fibers in various irradiation conditions to evaluate the usability of Cerenkov radiation for a photon beam therapy dosimetry. As a results, the spectral peak of Cerenkov radiation was measured at a wavelength of 515 nm, and the intensity of Cerenkov radiation increased linearly with increasing irradiated length of the optical fiber. Also, the intensity peak of Cerenkov radiation was measured in the irradiation angle range of 30 to 40 deg. In the results of Monte Carlo N-particle transport code simulations, the relationship between fluxes of electrons over Cerenkov threshold energy and energy deposition of a 6 MV photon beam had a nearly linear trend. Finally, percentage depth doses for the 6 MV photon beam could be obtained using the CFOD and the results were compared with those of an ionization chamber. Here, the mean dose difference was about 0.6%. It is anticipated that the novel and simple CFOD can be effectively used for measuring depth doses in radiotherapy dosimetry.</P>
Cheol HoPyeon,Tetsushi Azuma,Yuki Takemoto,Takahiro Yagi,Tsuyoshi Misawa 한국원자력학회 2013 Nuclear Engineering and Technology Vol.45 No.1
Neutron spectrum analyses of spallation neutrons are conducted in the accelerator-driven system (ADS) facility at the Kyoto University Critical Assembly (KUCA). High-energy protons (100 MeV) obtained from the fixed field alternating gradient accelerator are injected onto a tungsten target, whereby the spallation neutrons are generated. For neutronic characteristics of spallation neutrons, the reaction rates and the continuous energy distribution of spallation neutrons are measured by the foil activation method and by an organic liquid scintillator, respectively. Numerical calculations are executed by MCNPX with JENDL/HE-2007 and ENDF/B-VI libraries to evaluate the reaction rates of activation foils (bismuth and indium) set at the target and the continuous energy distribution of spallation neutrons set in front of the target. For the reaction rates by the foil activation method, the C/E values between the experiments and the calculations are found around a relative difference of 10%, except for some reactions. For continuous energy distribution by the organic liquid scintillator, the spallation neutrons are observed up to 45 MeV. From these results, the neutron spectrum information on the spallation neutrons generated at the target are attained successfully in injecting 100 MeV protons onto the tungsten target.
Pyeon, Cheol Ho,Azuma, Tetsushi,Takemoto, Yuki,Yagi, Takahiro,Misawa, Tsuyoshi Korean Nuclear Society 2013 Nuclear Engineering and Technology Vol.45 No.1
Neutron spectrum analyses of spallation neutrons are conducted in the accelerator-driven system (ADS) facility at the Kyoto University Critical Assembly (KUCA). High-energy protons (100 MeV) obtained from the fixed field alternating gradient accelerator are injected onto a tungsten target, whereby the spallation neutrons are generated. For neutronic characteristics of spallation neutrons, the reaction rates and the continuous energy distribution of spallation neutrons are measured by the foil activation method and by an organic liquid scintillator, respectively. Numerical calculations are executed by MCNPX with JENDL/HE-2007 and ENDF/B-VI libraries to evaluate the reaction rates of activation foils (bismuth and indium) set at the target and the continuous energy distribution of spallation neutrons set in front of the target. For the reaction rates by the foil activation method, the C/E values between the experiments and the calculations are found around a relative difference of 10%, except for some reactions. For continuous energy distribution by the organic liquid scintillator, the spallation neutrons are observed up to 45 MeV. From these results, the neutron spectrum information on the spallation neutrons generated at the target are attained successfully in injecting 100 MeV protons onto the tungsten target.
DT Neutronics Benchmark Experiment on Lead at JAEA-FNS
Kentaro Ochiai,Keitaro Kondo,Seiki Ohnishi,Kosuke Takakura,Satoshi Sato,Yuichi Abe,Chikara Konno,Chihiro Suzuki,Takahiro Yagi 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23
Lead is one of the most important candidate materials for nuclear fusion reactor blankets. We have carried out an integral benchmark experiment on lead at the DT neutron source facility of JAEA, FNS. A cubic lead assembly on a side of 45.3 cm was set up and was irradiated with the DT neutron source. Reaction rates of the ^(27)Al(n,α)^(24)Na, ^(93)Nb(n,2n)^(92m)Nb, ^(90)Zr(n,2n)^(89)Zr, and ^(115)In(n,n')^(115m)In reactions and neutron spectra above 2 MeV were measured inside the assembly with activation foil and a small NE213 spectrometer, respectively. A Monte Carlo code, MCNP5, was adopted to calculate the reaction rates and neutron spectra. The latest nuclear data libraries, JENDL-3.3 ENDF/B-VII.0, JEFF-3.1 and FENDL-2.1, were used in the calculation. The calculation results with the three libraries except for JENDL-3.3 agreed with the measured reaction rates and neutron spectra. On the other hand, that with JENDL-3.3 underestimated the measured ones with the depth. We found out that the inappropriate evaluation of the (n,2n), elastic scattering and inelastic scattering reactions in the lead isotopes of JENDL-3.3 caused the disagreements.