Quasifree neutron knockout reaction reveals a small -Orbital component in the Borromean nucleus B

Yang, Z. H.*; Kubota, Yuki*; Corsi, A.*; Yoshida, Kazuki; Sun, X.-X.*; Li, J. G.*; Kimura, Masaaki*; Michel, N.*; Ogata, Kazuyuki*; Yuan, C. X.*; et al.

Physical Review Letters, 126(8), p.082501_1 - 082501_8, 2021/02

AA2020-0819.pdf:1.29MB

https://doi.org/10.1103/PhysRevLett.126.082501

A quasifree (,) experiment was performed to study the structure of the Borromean nucleus B, which had long been considered to have a neutron halo. By analyzing the momentum distributions and exclusive cross sections, we obtained the spectroscopic factors for and orbitals, and a surprisingly small percentage of 9(2)% was determined for . Our finding of such a small component and the halo features reported in prior experiments can be explained by the deformed relativistic Hartree-Bogoliubov theory in continuum, revealing a definite but not dominant neutron halo in B. The present work gives the smallest - or -orbital component among known nuclei exhibiting halo features and implies that the dominant occupation of or orbitals is not a prerequisite for the occurrence of a neutron halo.

Probing carbon edge exposure of iron phthalocyanine-based oxygen reduction catalysts by soft X-ray absorption spectroscopy

Niwa, Hideharu*; Saito, Makoto*; Kobayashi, Masaki*; Harada, Yoshihisa*; Oshima, Masaharu*; Moriya, Shogo*; Matsubayashi, Katsuyuki*; Nabae, Yuta*; Kuroki, Shigeki*; Ikeda, Takashi; et al.

Journal of Power Sources, 223, p.30 - 35, 2013/02

https://doi.org/10.1016/j.jpowsour.2012.09.031

To design non-platinum, inexpensive, but high performance carbon-based cathode catalysts for polymer electrolyte fuel cells, it is important to elucidate the active site for oxygen reduction reaction (ORR). However, it is difficult to directly identify the active site by applying conventional structural or electronic probes to such complex systems. Here, we used C 1 X-ray absorption spectroscopy (XAS) to observe electronic structure of carbon in iron phthalocyanine-based catalysts, and found a signature of edge exposure below the edge, whose intensity is well correlated with the ORR activity. These results demonstrate that C 1 XAS can be used to characterize the ORR activity of carbon-based cathode catalysts in terms of the edge exposure.

Research facilities for International Fusion Energy Research Centre of Broader Approach Activities at Rokkasho

Ohira, Shigeru; Utsumi, Shigeo*; Kubo, Takashi; Yonemoto, Kazuhiro; Kasuya, Kenichi; Ejiri, Shintaro; Kimura, Haruyuki; Okumura, Yoshikazu

Journal of Plasma and Fusion Research SERIES, Vol.9, p.665 - 669, 2010/08

http://www.jspf.or.jp/JPFRS/PDF/Vol9/jpfrs2010_09-665.pdf

Under the Agreement Between the Government of Japan and the EURATOM for the Joint Implementation of the Broader Approach Activities (BA Activities) in the Field of Fusion Energy Research, JAEA develop a new site at Rokkasho-mura in Aomori prefecture of Japan as the Japanese Implementing Agency. In this new site, two of the three projects of the BA Activities are to be implemented, namely, International Fusion Energy Research Center (IFERC) Project and International Fusion Material Irradiation Facility/Engineering Validation and Engineering Design Activity (IFMIF/EVEDA) Project. In March 2009, the Administration and Research Building was completed, and the other research facilities; CSC&REC Building, DEMO R&D Building and IFMIF/EVEDA Accelerator Building will be completed in March 2010. In this presentation, the specifications and construction schedule of the individual research buildings will be presented, especially special features of the IFMIF/EVEDA Accelerator Building.

A Study on design methods for over pack welds; Acquisition of basic data to quantify welding quality

*; *; *; *; Sago, Hiromi*; *; *

JNC TJ8400 2000-048, 30 Pages, 2000/02

JNC-TJ8400-2000-048.pdf:1.64MB

In this study basic data on welds of overpack structures for HLW were acquired and a predictive destruction analysis was performed using the data acquired, in order to examine the viability of weld design methods. The results are summarized as follows: (1)Investigation of Design and Welding Conditions for Welded Joint Models. Three welding methods--EBW, TIG and MAG-were selected, and welding conditions were determined so that the welding quality almost equivalent to that of an actual over-pack was ensured. (2)Fabrication of Welded Joint Models. Three welded joint models, one for each of EBW, TIG and MAG, were fabricated. It was confirmed that these models satisfied the quality requirements for Class I specified in JIS Z3104. (3)Sampling and Machining of Strength Test Specimens. Test specimens were taken from each welded joint model, and models for corrosion tests were delivered to the Japan Nuclear Cycle Development Institute (JNC). (4)Strength Test and Micro/macro Structure observation. Tensile tests were conducted at room temperature and at 150C, and fracture toughness tests at 0C and 150C, in order to obtain stress-strain curves, J-R curves and Vickers hardness. In addition, an observation of micro and macro structures was performed. (5)Evaluation. Using the data on the welds obtained from the tests, a fracture prediction analysis and an evaluation of unstable fracture due to weld flaws were performed on the over-pack design described in the second progress report. The following conclusions were obtained: (a)For the overpack design examined, the effects of welds (material property and residual stress) and fabrication tolerance on fracture loading are negligible. (b)In addition, it was decided that even in a design with reduced wall thickness, welds have an insignificant effect on fracture loading because fracture initiates in the center of the shell of the overpack. (c)The size of flaws leading to unstable fracture is on the ...

Study on the structural integrity of overpacks

*; *; Kawahara, Kenichi*; *; *; *; *

JNC TJ8400 99-050, 310 Pages, 1999/02

JNC-TJ8400-99-050.pdf:8.92MB

In this study; a research and development plan for overpacks has been proposed by identifying issues for developing overpacks and organizing approaches for resolving them, as well as investigating a structural design methodology for overpacks and a quality control method in manufacturing them. The results are summarized as follows: (1)Technical Requirements for overpacks. Tentative technical requirements for overpacks are summarized on the survey of overseas literatures and performance assessment models discussed so far. (2)Determination of Reference Design. Handling and manufacturing methods for overpacks are discussed. Reference overpack structures are determined considering the discussion on the structural strength. (3)Approach to assuring structural integrity of overpacks. Load conditions and rupture modes after backfill are reviewed. A structural design methodology for overpacks was discussed based on FEM analyses. In addition, inspection items, which are necessary to assure that technical requirements are satisfied. (4)Destructive test. Destructive test is carried out in order to validate FEM analysis and others for basing a structural design methodology. As a consequence of the test, we could verify the sufficient reliability of FEM analysis and conservatism of the design methodology. (5)Quality control method. R&D items for quality control of overpacks are summarized based on the ideas of the order No. 78 issued by the Prime Minister's Office. Validation of measurement reliability for ultrasonic tests is the major R&D items in the future. (6)Preparation for R&D plan. A R&D plan for developing technical criteria, for overpacks is summarized.

Conceptual design of Fusion Experimental Reactor; Safety analysis and evaluation

Seki, Yasushi; Takatsu, Hideyuki; Iida, Hiromasa; *; Ogawa, Masuro; Noguchi, Hiroshi; Murata, Mikio; *; *; *; et al.

JAERI-M 91-126, 511 Pages, 1991/08

JAERI-M-91-126.pdf:12.54MB

no abstracts in English