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Journal Articles

The Operation status of the superconducting cavity for CERL main linac; Toward the deep understanding inside the superconducting cavity with high current beam

Numata, Naoto*; Asakawa, Tomoyuki*; Sakai, Hiroshi*; Umemori, Kensei*; Furuya, Takaaki*; Shinoe, Kenji*; Enami, Kazuhiro*; Egi, Masato*; Sakanaka, Shogo*; Michizono, Shinichiro*; et al.

Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.566 - 570, 2015/09

no abstracts in English

Journal Articles

Basic vacuum test of 500-kV photocathode DC gun components at KEK

Yamamoto, Masahiro*; Uchiyama, Takashi*; Miyajima, Tsukasa*; Honda, Yosuke*; Sato, Kotaro*; Matsuba, Shunya*; Saito, Yoshio*; Kobayashi, Masanori*; Kurisu, Hiriki*; Hajima, Ryoichi; et al.

Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.717 - 720, 2010/08

A 500-kV photocathode DC electron gun which can supply the beam of a low emittance and a high average current has been developed in collaboration with KEK, JAEA, Hiroshima Univ., Nagoya Univ. and Yamaguchi Univ. The vacuum of the gun chamber has to be lower Extreme High Vacuum for maintain cathode-life time. A titanium chamber and new material of ceramic were employed to reduce outgassing rate. The result of outgassing rate of the gun chamber is described in this report.

Journal Articles

Development of a prototype module for the ERL superconducting main linac at KEK

Furuya, Takaaki*; Hara, Kazufumi*; Hosoyama, Kenji*; Kojima, Yuji*; Nakai, Hirotaka*; Nakanishi, Kota*; Sakai, Hiroshi*; Umemori, Kensei*; Sawamura, Masaru; Shinoe, Kenji*

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.2923 - 2925, 2010/05

A prototype module including a couple of 1.3 GHz superconducting 9-cell cavities has been designed as the main linac of cERL which is the test facility to establish the basic ERL technology at KEK. The shape of 9-cell Nb structure is optimized to accelerate a CW beam of 100 mA with sufficiently damped higher order modes (HOM) which is achieved by adopting an eccentric fluted beam pipe and a cylindrical beam pipe of a large diameter of 120 mm. Extracted HOMs are absorbed by the ferrite cylinders bonded on the copper beam pipes by HIP process. A power coupler with double disk-ceramics has been developed to transfer an RF of 20 kW CW to the cavity in full reflection. The test results of fabrication, cooling and RF performance for these components are integrated as the prototype module of the main linac for cERL facility.

Journal Articles

Recent progress in the energy recovery linac project in Japan

Sakanaka, Shogo*; Akemoto, Mitsuo*; Aoto, Tomohiro*; Arakawa, Dai*; Asaoka, Seiji*; Enomoto, Atsushi*; Fukuda, Shigeki*; Furukawa, Kazuro*; Furuya, Takaaki*; Haga, Kaiichi*; et al.

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.2338 - 2340, 2010/05

Future synchrotron light source using a 5-GeV energy recovery linac (ERL) is under proposal by our Japanese collaboration team, and we are conducting R&D efforts for that. We are developing high-brightness DC photocathode guns, two types of cryomodules for both injector and main superconducting (SC) linacs, and 1.3 GHz high CW-power RF sources. We are also constructing the Compact ERL (cERL) for demonstrating the recirculation of low-emittance, high-current beams using above-mentioned critical technologies.

Journal Articles

Development of passive shutdown system for SFR

Nakanishi, Shigeyuki*; Hosoya, Takusaburo; Kubo, Shigenobu*; Kotake, Shoji; Takamatsu, Misao; Aoyama, Takafumi; Ikarimoto, Iwao*; Kato, Jungo*; Shimakawa, Yoshio*; Harada, Kiyoshi*

Nuclear Technology, 170(1), p.181 - 188, 2010/04

 Times Cited Count:12 Percentile:66.94(Nuclear Science & Technology)

A self-actuated shutdown system (SASS) for sodium cooled fast reactor (SFR) is a passive safety feature which inserts control rods by the gravity force, where the detachment of the rods would be achieved by the coolant temperature rise under anticipated transient without scram (ATWS) conditions. Various out-of-pile tests have already carried out to investigate the basic characteristics of SASS, and a demonstration test of holding stability under the reactor operation condition has been performed, where a function test of the driving system to re-connect and of pulling out the control rod have been done in the experimental reactor JOYO. The element irradiation tests have been also conducted to confirm that no impact will be foreseen by the irradiation. The effectiveness of SASS for a reference core design of JSFR has been evaluated through all types of ATWS. As a result, it is ensured that JSFR will have a reliable passive shutdown system.

Journal Articles

Design of a 500kV electron gun for ERL light source at KEK

Yamamoto, Masahiro*; Honda, Yosuke*; Miyajima, Tsukasa*; Uchiyama, Takashi*; Kobayashi, Masanori*; Muto, Toshiya*; Matsuba, Shunya*; Sakanaka, Shogo*; Sato, Kotaro*; Saito, Yoshio*; et al.

Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.860 - 862, 2009/08

A newly 500 kV electron gun (2nd - 500 kV gun) for an ERL light source is designed at KEK. A new concept and state of-the-art technologies of vacuum system, ceramic insulators, high voltage power supply, photocathode and preparation system will be employed. The details are described in this report.

Journal Articles

Study on flow-induced-vibration evaluation of the large-diameter pipings in a sodium-cooled fast reactor, 3; Random vibration analysis method based on turbulence energy calculated by CFD

Hirota, Kazuo*; Ishitani, Yoshihide*; Nishida, Keigo*; Sago, Hiromi*; Xu, Y.*; Yamano, Hidemasa; Nakanishi, Shigeyuki; Kotake, Shoji

Proceedings of 6th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-6) (USB Flash Drive), 8 Pages, 2008/11

CFD simulation using the Reynolds stress model was performed to evaluate turbulence-induced forces on the piping. The turbulence energy with the CFD simulation was compared with pressure fluctuation distributions obtained by the test with a 1/3 scale elbow simulating the JSFR hot-leg piping. The profile of turbulence energy was good agreement with that of the pressure fluctuation. The magnitude of pressure fluctuation can also be estimated from calculated turbulence energy multiplied by a certain coefficient. In the vibration analysis, the power spectrum density (PSD) of the pressure fluctuation was derived from the measured normalized PSD multiplied by the coefficient. The vibration analysis method was proposed based on the PSDs derived by the above procedure and correlation lengths. The analysis results of vibration response showed good agreement with the flow-induced-vibration test results, thereby it can be said that the vibration analysis method developed in this study is valid.

Journal Articles

Study on flow-induced-vibration evaluation of large-diameter pipings in a sodium-cooled fast reactor, 1; Sensitivity analysis of turbulent flow models for unsteady short-elbow pipe flow

Aizawa, Kosuke; Nakanishi, Shigeyuki; Yamano, Hidemasa; Kotake, Shoji; Hayakawa, Satoshi*; Watanabe, Osamu*; Fujimata, Kazuhiro*

Proceedings of 6th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-6) (USB Flash Drive), 7 Pages, 2008/11

To evaluate the flow-induced vibration in the actual-sized pipings of JSFR, computer simulation is necessary. In this study, as the first step, sensitivity analysis of turbulence flow models for unsteady short-elbow pipe flow has been carried out with the STAR-CD thermal-hydraulic simulation code. Through the sensibility analysis, the objective of this study is to propose the best analysis models which can reproduce the unsteady characteristics obtained in the 1/3-scale test results with 9.2 m/s of main flow. In this study, to take into account anisotropic characteristics of turbulence, two turbulent flow models were used: large eddy simulation (LES) and Reynolds stress model (RSM). The both validated simulations have reproduced flow separation region and periodic vortex shedding. The simulation results with both models were compared with power spectrum densities of pressure fluctuations which were used in the pipe vibration evaluation. Only the RSM simulation with the best combination has reproduced the pressure-fluctuation power spectrum densities, which were characterized by a peak frequency of 10 Hz in the 1/3 test with 9.2 m/s.

Journal Articles

Vanadium uptake and an effect of vanadium treatment on $$^{18}$$F-labeled water movement in a cowpea plant by positron emitting tracer imaging system (PETIS)

Furukawa, Jun*; Yokota, Harumi*; Tanoi, Keitaro*; Ueoka, Shiori*; Matsuhashi, Shimpei; Ishioka, Noriko; Watanabe, Satoshi; Uchida, Hiroshi*; Tsuji, Atsunori*; Ito, Takehito*; et al.

Journal of Radioanalytical and Nuclear Chemistry, 249(2), p.495 - 498, 2001/08

 Times Cited Count:14 Percentile:70.96(Chemistry, Analytical)

We present real time Vanadate (V$$^{5+}$$) uptake imaging in a cowpea plant by Positron Emitting Tracer Imaging System (PETIS). Vanadium-48 was produced by bombarding a Sc foil target with 50 MeV $$alpha$$-particles at Takasaki Ion accelerators for Advanced Radiation Application (TIARA) AVF cyclotron. Then $$^{48}$$V was added to the culture solution to investigate the V distribution in a cowpea plant. The real time uptake of the $$^{48}$$V was monitored by PETIS. We measured the distribution of $$^{48}$$V in a whole plant after 3, 6 and 20 hours of V treatment by Bio-imaging Analyzer System (BAS). After the 20 hour treatment, vanadate was detected at the up-ground part of the plant. To know the effect of V uptake on plant activity, $$^{18}$$F-labeled water uptake was analyzed by PETIS. When a cowpea plant was treated with V for 20 hours before $$^{18}$$F-labeled water uptake experiment, the total amount of $$^{18}$$F-labeled water absorption was drastically desreased. Results suggest the inhibition of water uptake was mainly caused by the vanadate already moved to the up-ground part of the plant.

Journal Articles

$$^{18}$$F used as tracer to study water uptake and transport imaging of a cowpea plant

Nakanishi, Tomoko*; Tanoi, Keitaro*; Yokota, Harumi*; Kang, D.-J.*; Ishii, Ryuichi*; Ishioka, Noriko; Watanabe, Satoshi; Osa, Akihiko; Sekine, Toshiaki; Matsuhashi, Shimpei; et al.

Journal of Radioanalytical and Nuclear Chemistry, 249(2), p.503 - 507, 2001/08

We present the water uptake ability of cowpea ($$it {Vigna unguliculata Walp.}$$) which has been regarded as one of the most drought resistant species among the pulse crops. It has been suggested that in the lower part of the stem, parenchymatous tissue for storing water had been developed for the function of deought resistance. We confirmed that in this tissue, water amount was high compared to the other stems by neutron radiography. Then the water uptake manner was measured by positron emitting tracer imaging system (PETIS) using $$^{18}$$F labeled water produced by a cyclotron. Comparing the water uptake manner of cowpea plant with that of common bean, cowpea plant was found to maintain high water uptake activity after drying treatment, suggesting the high drought resistant character.

Journal Articles

Comparison of $$^{15}$$O-labeled and $$^{18}$$F-labeled water uptake in a soybean plant by PETIS (Positron Emitting Tracer Imaging System)

Nakanishi, Tomoko*; Yokota, Harumi*; Tanoi, Keitaro*; Ikeue, Natsuko*; Okuni, Yoko*; Furukawa, Jun*; Ishioka, Noriko; Watanabe, Satoshi; Osa, Akihiko; Sekine, Toshiaki; et al.

Radioisotopes, 50(6), p.265 - 269, 2001/06

$$^{15}$$O-Labeled and $$^{18}$$F-Labeled water uptake manner in a soybean plant was compared by PETIS (Positron Emitting Tracer Imaging System). $$^{15}$$O-Labeled water (half-life: 2 min) and $$^{18}$$F-Labeled water (half-life: 110 min) were produced by a cyclotron by $$^{14}$$N(d,n)$$^{15}$$O and $$^{16}$$O($$alpha$$,pn)$$^{18}$$F reactions, respectively. A root of a soybean plant was cut off and each labeled water was supplied from the basal part of the plant. The gamma-rays emitted from the sample was measured by a BGO counter with a detection area of 5 cm$$times$$15 cm. The radioactivity from each stem was accumlated every 15 s till 20 min. It was found that $$^{18}$$F-labeled water was taken up much faster than $$^{15}$$O-labeled water, suggesting that in $$^{18}$$F-labeled water, fluorine was moved in the form of $$^{18}$$F-ion. When BAS image of $$^{15}$$O-labeled water in a plant after 5 min and 10 min of water supply was taken, it was found that the labeled water was observed only in the lowest internode, between a root and the first leaves.

Journal Articles

Experimental results of laser wakefield acceleration using a femtosecond laser pulse

Kando, Masaki; Ahn, H.; Dewa, Hidenori; Kotaki, Hideyuki; Ueda, Toru*; Uesaka, Mitsuru*; Watanabe, Takahiro*; Nakanishi, Hiroshi*; Ogata, Atsushi*; Nakajima, Kazuhisa

Japanese Journal of Applied Physics, Part 2, 38(8B), p.L967 - L969, 1999/08

 Times Cited Count:23 Percentile:70.07(Physics, Applied)

no abstracts in English

Journal Articles

Short pulse X-ray generation via backward Thomson scattering on relativistic electron beam

Kotaki, Hideyuki; Nakajima, Kazuhisa*; Kando, Masaki*; Dewa, Hidenori*; Kondo, Shuji; *; Watanabe, Takahiro*; Ueda, Toru*; Nakanishi, Hiroshi*; Yoshii, Koji*; et al.

Inst. Phys. Conf. Ser., (159), p.565 - 567, 1999/00

no abstracts in English

Journal Articles

Performance tests of BNL/KEK/SHI Protocathode RF gun

Kando, Masaki; Kotaki, Hideyuki; Dewa, Hidenori; Kondo, Shuji; Yoshii, Koji*; Ueda, Toru*; Watanabe, Takahiro*; Uesaka, Mitsuru*; Sakai, Fumio*; Ogata, Atsushi*; et al.

Proceedings of 24th Linear Accelerator Meeting in Japan, p.128 - 130, 1999/00

no abstracts in English

Journal Articles

Recent progress of laser wakefield acceleration experiments at KEK/U.Tokyo/JAERI

Nakajima, Kazuhisa; Nakanishi, Hiroshi*; Ogata, Atsushi*; Harano, Hideki*; Ueda, Toru*; Uesaka, Mitsuru*; Watanabe, Takahiro*; Yoshii, Koji*; Dewa, Hidenori; Hosokai, Tomonao; et al.

Proceedings of 6th European Particle Accelerator Conference (EPAC98) (CD-ROM), p.809 - 811, 1998/01

no abstracts in English

Journal Articles

Experiments of high energy gain laser wakefield acceleration

Dewa, Hidenori*; H.Ahn*; Harano, Hideki*; Kando, Masaki*; Kinoshita, Kenichi*; Kondo, Shuji; Kotaki, Hideyuki; Nakajima, Kazuhisa*; Nakanishi, Hiroshi*; Ogata, Atsushi*; et al.

Nuclear Instruments and Methods in Physics Research A, 410(3), p.357 - 363, 1998/00

 Times Cited Count:39 Percentile:93.39(Instruments & Instrumentation)

no abstracts in English

Journal Articles

A Short pulse X-ray generation via laser thomson scattering on relativistic electron beams

Kotaki, Hideyuki; Nakajima, Kazuhisa*; Kando, Masaki*; H.Ahn*; Dewa, Hidenori*; Kondo, Shuji; *; Watanabe, Takahiro*; Ueda, Toru*; Nakanishi, Hiroshi*; et al.

Proc. of 11th Symp. on Accelerator Sci. and Technol., p.449 - 451, 1997/00

no abstracts in English

Journal Articles

Development of high duty operation RF photoinjector

*; Kotaki, Hideyuki; Nakajima, Kazuhisa*; Kando, Masaki*; Kondo, Shuji; Dewa, Hidenori*; Watanabe, Takahiro*; Ueda, Toru*; Yoshii, Koji*; Kinoshita, Kenichi*; et al.

Proc. of 11th Symp. on Accelerator Sci. and Technol., p.473 - 475, 1997/00

no abstracts in English

Journal Articles

Laser Wakefield Acceleration Experiments

Kotaki, Hideyuki; Nakajima, Kazuhisa*; Kando, Masaki*; H.Ahn*; Dewa, Hidenori*; Kondo, Shuji; *; Watanabe, Takahiro*; Ueda, Toru*; Nakanishi, Hiroshi*; et al.

Proc. of 11th Symp. on Accelerator Sci. and Technol., p.513 - 515, 1997/00

no abstracts in English

Oral presentation

Evaluation of dissolved $$^{137}$$Cs discharge characteristics from a forested catchment of the Ohta River

Sakuma, Kazuyuki; Yoshimura, Kazuya; Nakanishi, Takahiro; Funaki, Hironori; Tsuruta, Tadahiko; Ochi, Kotaro; Hayashi, Seiji*; Tsuji, Hideki*; Ozaki, Hirokazu*

no journal, , 

Cesium-137 leaching from decomposing forest litter is thought to be one pathway by which dissolved $$^{137}$$Cs enters rivers from forests. To clarify whether this process contributes or not, we studied the correlation between humin-like matter from microorganism-induced plants decomposition and dissolved $$^{137}$$Cs concentrations. River water samples were collected approximately once a month from April 2017 to August 2019 at 10 locations (7 locations from April 2019) from the upstream of the Ohta River in the Namie and Minamisoma districts. These samples were filtered through 0.45-$$mu$$m-pore size membrane filters. The dissolved $$^{137}$$Cs concentrations and fluorescence intensities of humin-like matter were measured. A positive correlation was found between the fluorescence intensities of humin-like matter and normalized dissolved $$^{137}$$Cs concentration (R$$^{2}$$ = 0.17, p $$<$$ 0.001). The results indicate that $$^{137}$$Cs leaching from forest litter because of litter decomposition can contribute to increasing the dissolved $$^{137}$$Cs concentration in river water in forested catchments.

Oral presentation

High-resolution analysis of lake sediments collected from Lake Harutori in Kushiro City, eastern Hokkaido, Japan

Nakanishi, Toshimichi; Nanayama, Futoshi*; Katsuki, Kota*; Yamada, Keitaro*

no journal, , 

The Holocene sediments of Lake Harutori in Kushiro City, eastern Hokkaido, are mainly composed of annually laminated sediments, organic mud layers with plant fragments, sand layers with shell and plant fragments and tephra layers. Fluctuations of the marine reservoir effect of radiocarbon and the information on the paleo-tsunami caused by the huge interplate earthquakes were identified by the high-resolution sedimentological analysis.

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