Measurement of double-differential thick-target neutron yields of the C() reaction at 12, 20, and 30 MeV

Patwary, M. K. A*; Kin, Tadahiro*; Aoki, Katsumi*; Yoshinami, Kosuke*; Yamaguchi, Masaya*; Watanabe, Yukinobu*; Tsukada, Kazuaki; Sato, Nozomi*; Asai, Masato; Sato, Tetsuya; et al.

Journal of Nuclear Science and Technology, 58(2), p.252 - 258, 2021/02

https://doi.org/10.1080/00223131.2020.1819908

While designing deuteron accelerator neutron sources for radioisotopes production, nuclear data for light elements such as Li, Be, and C have been systematically measured in the deuteron energy range from a few MeV to around 50 MeV. Currently, the experimental data available on double-differential thick-target neutron yields (DDTTNYs) is insufficient, especially for deuteron energies between 18 and 33 MeV. In this study, we measured the DDTTNYs of () reactions on C target for incident deuteron energies of 12, 20, and 30 MeV using the multiple-foils activation method to improve nuclear data insufficiency. We applied the GRAVEL code for the unfolding process to derive the DDTTNYs. The results were compared with the calculation by DEURACS. The present data were also used to confirm the systematics of the differential neutron yields at 0 and total neutron yield per incident deuteron in the wide range of deuteron energy.

Survey results for the transition of the air dose rate after the Cabinet Office decontamination model demonstration project; 1st-11th survey results summary (Contract research)

Kawase, Keiichi; Kitano, Mitsuaki; Watanabe, Masanori; Yoshimura, Shuichi; Kikuchi, Shiro; Nishino, Katsumi*

JAEA-Review 2017-006, 173 Pages, 2017/03

JAEA-Review-2017-006.pdf:35.6MB
JAEA-Review-2017-006-appendix(CD-ROM).zip:0.52MB

Survey of a transition of the air and surface dose rate was conducted for the area where the Cabinet Office decontamination model demonstration project was implemented. The area includes 15 districts in 9 municipalities identified by the Ministry of the Environment. We investigated 11 times from October, 2012 to October, 2015. Measurement of the air dose rate in this study was carried out in two methods using the fixed-point measurement and gamma plotter H using a NaI scintillation survey meter etc. As fixed-point measurement, set measurement point in the first survey for (fixed point), it was subjected to measurement of the surface dose rate to continue (1cm height) and space dose rate (1m height). In addition surface specific dose rate distribution measurement using a gamma plotter H (5cm and 1m height) was also performed together. As a result of the fixed-point measurement and gamma plotter H surface measurements, space dose rate from the first survey to the 11th survey shows the downward trend. We consider that there is no movement of radioactive pollutants from outside decontamination model project area into decontamination model project area.

Full-coherent free electron laser seeded by 13th- and 15th-order harmonics of near-infrared femtosecond laser pulses

Sato, Takahiro*; Iwasaki, Atsushi*; Owada, Shigeki*; Yamanouchi, Kaoru*; Takahashi, Eiji*; Midorikawa, Katsumi*; Aoyama, Makoto; Yamakawa, Koichi; Togashi, Tadashi*; Fukami, Kenji*; et al.

Journal of Physics B; Atomic, Molecular and Optical Physics, 46(16), p.164006_1 - 164006_6, 2013/08

https://doi.org/10.1088/0953-4075/46/16/164006

By introducing 13th- (61.7 nm) and 15th-order harmonics (53.4 nm) of femtosecond laser pulses at 800 nm into an undulator of SCSS (SPring-8 Compact SASE Source) test accelerator at RIKEN, these harmonic pulses were amplified by a factor of more than 10 with a high contrast ratio through the interaction between accelerated electron bunches and the harmonic pulses. From numerical simulations of the amplification processes of high-order harmonic pulses in the undulator, optimum conditions of the electron bunch duration interacting with the high-order harmonic pulses were investigated for generating full-coherent and intense pulses in the extreme ultraviolet wavelength region.

High intense full-coherent radiation of free electron laser seeded by high-order harmonics in extreme-ultraviolet region

Togashi, Tadashi*; Takahashi, Eiji*; Midorikawa, Katsumi*; Aoyama, Makoto; Yamakawa, Koichi; Sato, Takahiro*; Iwasaki, Atsushi*; Owada, Shigeki*; Yamanouchi, Kaoru*; Hara, Toru*; et al.

Proceedings of Ultrafast Optics IX (CD-ROM), 2 Pages, 2013/03

We have demonstrated free-electron laser radiation seeded by high-order harmonics in the extreme-ultraviolet region. Strong enhancement of the radiation intensity by a factor of 104 was observed with timing control of an electro-optical sampling technique.

Extreme ultraviolet free electron laser seeded by high-order harmonic

Togashi, Tadashi*; Takahashi, Eiji*; Midorikawa, Katsumi*; Aoyama, Makoto; Yamakawa, Koichi; Sato, Takahiro*; Iwasaki, Atsushi*; Owada, Shigeki*; Yamanouchi, Kaoru*; Hara, Toru*; et al.

Proceedings of 11th International School and Symposium on Synchrotron Radiation in Natural Science (ISSRNS 2012), p.1 - 21, 2012/05

The 13th harmonic of a Ti:sapphire laser has been significantly amplified with the SCSS test accelerator. The temporal and spatial overlap of the electron beam and the high harmonic radiation were precisely tuned for achieving the seeded free electron laser operation. With numerical simulation the present HH-seeded FEL scheme could readily be applied to the wavelength region down to 10 nm.

Development of the JT-60SA Neutral Beam Injectors

Hanada, Masaya; Kojima, Atsushi; Inoue, Takashi; Watanabe, Kazuhiro; Taniguchi, Masaki; Kashiwagi, Mieko; Tobari, Hiroyuki; Umeda, Naotaka; Akino, Noboru; Kazawa, Minoru; et al.

AIP Conference Proceedings 1390, p.536 - 544, 2011/09

https://doi.org/10.1063/1.3637425

no abstracts in English

Seeding of extreme ultraviolet free electron laser with high-order harmonic

Takahashi, Eiji*; Togashi, Tadashi*; Midorikawa, Katsumi*; Aoyama, Makoto; Yamakawa, Koichi; Sato, Takahiro*; Iwasaki, Atsushi*; Owada, Shigeki*; Yamanouchi, Kaoru*; Hara, Toru*; et al.

Proceedings of European Conference on Lasers and Electro-Optics and the 12th European Quantum Electronics Conference (CLEO/Europe-EQEC 2011) (CD-ROM), 1 Pages, 2011/05

http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5943030

We succeeded in generating the seeded free electron laser (FEL) with wavelengths of 61 nm at the SCSS test accelerator. The 13th (61 nm) harmonics generated by focusing the high peak power Ti:Sapphire laser to the Xe gas cell was directed to the undulator. This is first realization of the seeded FEL in extreme ultraviolet region.

Demonstration of 500 keV beam acceleration on JT-60 negative-ion-based neutral beam injector

Kojima, Atsushi; Hanada, Masaya; Tanaka, Yutaka*; Kawai, Mikito*; Akino, Noboru; Kazawa, Minoru; Komata, Masao; Mogaki, Kazuhiko; Usui, Katsutomi; Sasaki, Shunichi; et al.

Proceedings of 23rd IAEA Fusion Energy Conference (FEC 2010) (CD-ROM), 8 Pages, 2011/03

http://www-naweb.iaea.org/napc/physics/FEC/FEC2010/html/node294.htm#62473

Hydrogen negative ion beams of 490keV, 3A and 510 keV, 1A have been successfully produced in the JT-60 negative ion source with three acceleration stages. These successful productions of the high-energy beams at high current have been achieved by overcoming the most critical issue, i.e., a poor voltage holding of the large negative ion sources with the grids of 2 m for JT-60SA and ITER. To improve voltage holding capability, the breakdown voltages for the large grids was examined for the first time. It was found that a vacuum insulation distance for the large grids was 6-7 times longer than that for the small-area grid (0.02 m). From this result, the gap lengths between the grids were tuned in the JT-60 negative ion source. The modification of the ion source also realized a significant stabilization of voltage holding and a short conditioning time. These results suggest a practical use of the large negative ion sources in JT-60 SA and ITER.

Development and design of the negative-ion-based NBI for JT-60 Super Advanced

Hanada, Masaya; Akino, Noboru; Endo, Yasuei; Inoue, Takashi; Kawai, Mikito; Kazawa, Minoru; Kikuchi, Katsumi; Komata, Masao; Kojima, Atsushi; Mogaki, Kazuhiko; et al.

Journal of Plasma and Fusion Research SERIES, Vol.9, p.208 - 213, 2010/08

http://www.jspf.or.jp/JPFRS/PDF/Vol9/jpfrs2010_09-207.pdf

A large negative ion source with an ion extraction area of 110 cm 45 cm has been developed to produce 500 keV, 22 A D ion beams required for JT-60 Super Advanced. To realize the JT-60SA negative ion source, the JT-60 negative ion source has been modified and tested on the negative-ion-based neutral beam injector on JT-60U. A 500 keV H ion beam has been produced at 3 A without a significant degradation of beam optics. This is the first demonstration of a high energy negative ion acceleration of more than one-ampere to 500 keV in the world. The beam current density of 90 A/m is being increased to meet 130 A/m of the design value for JT-60SA by tuning the operation parameters. A long pulse injection of 30 s has been achieved at a injection D power of 3 MW. The injection energy, defined as the product of the injection time and power, reaches 80 MJ by neutralizing a 340 keV, 27 A D ion beam produced with two negative ion sources.

Improvement of voltage holding capability in the 500 keV negative ion source for JT-60SA

Tanaka, Yutaka; Hanada, Masaya; Kojima, Atsushi; Akino, Noboru; Shimizu, Tatsuo; Oshima, Katsumi; Inoue, Takashi; Watanabe, Kazuhiro; Taniguchi, Masaki; Kashiwagi, Mieko; et al.

Review of Scientific Instruments, 81(2), p.02A719_1 - 02A719_3, 2010/02

https://doi.org/10.1063/1.3279399

The JT-60U negative ion source is required to produce 44 A of 500 keV D ion beams for the JT-60SA. So far, acceleration voltage of 450 kV was achieved without beam acceleration and 416 kV with beam acceleration. These are lower than the rated voltage for JT-60SA due to vacuum breakdowns. To examine the cause of vacuum breakdown, the complicated structure of the accelerator was modeled for the calculation of electric field inside the accelerator. At the corners of the grid support flanges, the electric fields are locally concentrated to be 5.2-5.5 kV/mm. This is higher than other parts of the accelerator where the averaged field is around 3 kV/mm. To reduce the concentrated electric field, the support structures were modified to extend the gap lengths between grids. By repeating the high-voltage application of 3 s pulses, the applied voltage was increased. After 15 hours of conditioning, the accelerator sustained its rated value of 500 kV without beam acceleration.