Design and actual performance of J-PARC 3 GeV rapid cycling synchrotron for high-intensity operation

Yamamoto, Kazami; Kinsho, Michikazu; Hayashi, Naoki; Saha, P. K.; Tamura, Fumihiko; Yamamoto, Masanobu; Tani, Norio; Takayanagi, Tomohiro; Kamiya, Junichiro; Shobuda, Yoshihiro; et al.

Journal of Nuclear Science and Technology, 59(9), p.1174 - 1205, 2022/09

https://doi.org/10.1080/00223131.2022.2038301

In the Japan Proton Accelerator Research Complex, the purpose of the 3 GeV rapid cycling synchrotron (RCS) is to accelerate a 1 MW, high-intensity proton beam. To achieve beam operation at a repetition rate of 25 Hz at high intensities, the RCS was elaborately designed. After starting the RCS operation, we carefully verified the validity of its design and made certain improvements to establish a reliable operation at higher power as possible. Consequently, we demonstrated beam operation at a high power, namely, 1 MW. We then summarized the design, actual performance, and improvements of the RCS to achieve a 1 MW beam.

Identification of hydrogen species on Pt/AlO by inelastic neutron scattering and their reactivity with ethylene

Yamazoe, Seiji*; Yamamoto, Akira*; Hosokawa, Saburo*; Fukuda, Ryoichi*; Hara, Kenji*; Nakamura, Mitsutaka; Kamazawa, Kazuya*; Tsukuda, Tatsuya*; Yoshida, Hisao*; Tanaka, Tsunehiro*

Catalysis Science & Technology, 11(1), p.116 - 123, 2021/01

https://doi.org/10.1039/D0CY01968B

Probabilistic risk assessment method development for high temperature gas-cooled reactors, 2; Development of accident sequence analysis methodology

Matsuda, Kosuke*; Muramatsu, Ken*; Muta, Hitoshi*; Sato, Hiroyuki; Nishida, Akemi; Ohashi, Hirofumi; Itoi, Tatsuya*; Takada, Tsuyoshi*; Hida, Takenori*; Tanabe, Masayuki*; et al.

Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 7 Pages, 2017/04

This paper proposes a set of procedures for accident sequence analysis in seismic PRAs of HTGRs that can consider the unique accident progression characteristics of HTGRs. Main features of our proposed procedure are as follows: (1) Systematic analysis techniques including Master Logic Diagrams are used to ensure reasonable completeness in identification of initiating events and classification of accident sequences, (2) Information on factors that govern the accident progression and source terms are effectively reflected to the construction of event trees for delineation of accident sequences, and (3) Frequency quantification of seismically-initiated accident sequence frequencies that involve multiplepipe ruptures are made with the use of the Direct Quantification of Fault Trees by Monte Carlo (DQFM) method by a computer code SECOM-DQFM.

Analysis on effects of transverse electric field in an injector cavity of compact-ERL at KEK

Hwang, J.-G.*; Kim, E.-S.*; Miyajima, Tsukasa*; Honda, Yosuke*; Harada, Kentaro*; Shimada, Miho*; Takai, Ryota*; Kume, Tatsuya*; Nagahashi, Shinya*; Obina, Takashi*; et al.

Nuclear Instruments and Methods in Physics Research A, 753, p.97 - 104, 2014/07

https://doi.org/10.1016/j.nima.2014.03.045

Analysis of buried heterointerfacial hydrogen in highly lattice-mismatched epitaxy on silicon

Yamazaki, Tatsuya; Asaoka, Hidehito; Taguchi, Tomitsugu; Yamamoto, Shunya; Yamazaki, Dai; Maruyama, Ryuji; Takeda, Masayasu; Shamoto, Shinichi

Thin Solid Films, 520(8), p.3300 - 3303, 2012/02

https://doi.org/10.1016/j.tsf.2011.10.081

We succeeded in realizing the epitaxial growth of a Sr layer on Si(111) with an atomically abrupt heterointerface - in spite of its large lattice mismatch (12%) with Si - by introducing a monoatomic layer of H on Si. In order to identify the buried H, we carried out a combination analysis involving neutron reflectometry and resonant nuclear reaction of H(N,)C analysis. We found different neutron reflectivity profiles resulting from a contrast variation between the H and D atoms at the buried heterointerface. Furthermore, the depth -ray intensity profiles revealed that the H at the heterointerface acts as an effective buffer layer that enables it to manage the highly mismatched epitaxy on Si.

Beam study results with HBC stripping foils at the 3-GeV RCS in J-PARC

Yoshimoto, Masahiro; Yamazaki, Yoshio; Hayashi, Naoki; Yamamoto, Kazami; Saeki, Riuji; Hotchi, Hideaki; Saha, P. K.; Harada, Hiroyuki; Kawase, Masato; Ishiyama, Tatsuya; et al.

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.3927 - 3929, 2010/05

http://accelconf.web.cern.ch/AccelConf/IPAC10/papers/thpeb020.pdf

The ()ybrid type thick ()oron-doped ()arbon (HBC) stripping foils are installed and used for the beam injection at the 3GeV RCS (Rapid Cycling Synchrotron) in J-PARC (Japan Proton Accelerator Research Complex). Up to now, the performance deterioration of the stripping foils can not be seen after the long beam irradiation for the 120kW user operation and 300kW high power beam demonstration at the RCS. In order to examine the characteristic of the HBC foils, various beam studies were carried out. The beam-irradiated spot at the foil was measured by scanning the foil setting position, the charge exchange efficiency was evaluated with various thickness foils, and the effect of the SiC fibers supporting the foil mounting was checked with different mounting foils. Beam study results obtained with using the HBC foils will be presented. In addition, the trends of outgas from the stripping foils and the deformations of the foils during the beam irradiation will be reported.

Ga NQR relaxation rates in superconductor PuRhGa

Sakai, Hironori; Kambe, Shinsaku; Tokunaga, Yo; Fujimoto, Tatsuya; Walstedt, R. E.*; Yasuoka, Hiroshi; Aoki, Dai*; Homma, Yoshiya*; Yamamoto, Etsuji; Nakamura, Akio; et al.

Journal of Physics and Chemistry of Solids, 68(11), p.2103 - 2106, 2007/11

https://doi.org/10.1016/j.jpcs.2007.08.039

A lot of attention is currently focused on Pu-based superconductors. These systems have relatively high superconducting (SC) transition temperatures, 18 K for PuCoGa and 9 K for PuRhGa. Both compounds crystallize in the tetragonal HoCoGa (115) structure, which is well known for the heavy-fermion SC systems CeIn (=Co, Rh, Ir)with 2 K at most. Recently, NMR and NQR experiments have been reported for PuCoGa by Curro et al. and for PuRhGa by our group. In both cases, measurements of using NQR have revealed that the Pu115 superconductors show unconventional superconductivity with an anisotropic gap. Now we have measured the more detailed data of for NQR lines in PuRhGa, especially focusing on the low-lying magnetic excitation in the normal state. From the viewpoint of spin-fluctuations, we will discuss the difference between PuRhGa and PuCoGa and between superconducting Pu115 and non-superconducting An115 series.

NMR studies of actinide dioxides

Tokunaga, Yo; Sakai, Hironori; Fujimoto, Tatsuya; Kambe, Shinsaku; Walstedt, R. E.*; Ikushima, Kenji*; Yasuoka, Hiroshi; Aoki, Dai*; Homma, Yoshiya*; Haga, Yoshinori; et al.

Journal of Alloys and Compounds, 444-445, p.241 - 245, 2007/10

https://doi.org/10.1016/j.jallcom.2007.03.082

In this paper, we present our recent NMR works on Neptunium and Plutonium compounds. In order to elucidate the nature of the exotic multipolar ordered phase of NpO, we have initiated the first NMR measurements on this system. We have shown that direct observation of multipole order parameters is possible by means of NMR. Our NMR results provide further insight into the microscopic nature of multipole phase transitions in f-electron systems. We have also performed Ga NMR/NQR studies on a single crystal of PuRhGa. From the temperature dependence of the spin-lattice relaxation rate (), we have found that PuRhGa is an unconventional superconductor having an anisotropic superconducting (SC) gap 2=5. Furthermore, we have confirmed the Knight shift to be decreased below . This gives strong evidence for spin singlet SC pairing.

Anisotropic spin fluctuations and anomalies of nuclear quadrupole interactions in the itinerant antiferromagnet NpCoGa; Co NMR and Ga NMR/NQR studies

Sakai, Hironori; Kambe, Shinsaku; Tokunaga, Yo; Fujimoto, Tatsuya*; Walstedt, R. E.*; Yasuoka, Hiroshi; Aoki, Dai*; Homma, Yoshiya*; Yamamoto, Etsuji; Nakamura, Akio; et al.

Physical Review B, 76(2), p.024410_1 - 024410_14, 2007/07

https://doi.org/10.1103/PhysRevB.76.024410

Nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR)experiments have been performed on a single crystal of NpCoGa with a Nel temperature =47 K. Knight shift, electric field gradient (EFG), frequency, and asymmetry parameter of the EFG are deduced for each site. These parameters are confirmed by NQR measurements in zero field. Hyperfine tensors for each site are deduced. Antiferromagnetic NMR spectra in zero field were also observed. A sharp anisotropy for spin fluctuations in NpCoGa has also been demonstrated.

NMR observation of quadrupolar order parameter in NpO

Tokunaga, Yo; Aoki, Dai*; Homma, Yoshiya*; Kambe, Shinsaku; Sakai, Hironori; Ikeda, Shugo; Fujimoto, Tatsuya; Walstedt, R. E.*; Yasuoka, Hiroshi; Shiokawa, Yoshinobu*; et al.

Journal of Magnetism and Magnetic Materials, 310(2, Part1), p.735 - 737, 2007/03

In this paper, we present recent and detailed O-NMR results obtained in a single crystal. From the analysis of the field-angle dependence of the NMR spectrum, the appearance of a hyperfine interaction with field-induced antiferro-octupole (AFO) moment has been confirmed. This field-induced AFO moment appears as a result of the longitudinal triple- antiferro-quadrupole (AFQ) structure in the ordered state. We have also observed spin echo modulations caused by quadrupole interactions between the O nuclei and the Np-5f quadrupole moments. This reveals that the AFQ structure is directly observable by NMR. Our NMR results provide further insight into the microscopic nature of multipole phase transitions in f-electron systems.