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Journal Articles

Analysis of nuclear structure in the nuclear chart and improvement to the gross theory of $$beta$$ decay

Endo, Fumitaka*; Koura, Hiroyuki

Physical Review C, 99(3), p.034303_1 - 034303_8, 2019/03

JAEA Reports

Proceedings of the 2017 Symposium on Nuclear Data; November 16-17, 2017, iVil, Tokai-mura, Ibaraki, Japan

Nishio, Katsuhisa; Utsuno, Yutaka; Chiba, Satoshi*; Koura, Hiroyuki; Iwamoto, Osamu; Nakamura, Shoji

JAEA-Conf 2018-001, 226 Pages, 2018/12

JAEA-Conf-2018-001.pdf:22.81MB

The 2017 Symposium on Nuclear Data was held at iVil in Tokai on November 16-17, 2017. The symposium was hosted by the Nuclear Data Division of the Atomic Energy Society of Japan (AESJ) and Advanced Science Research Center of Japan Atomic Energy Agency, and co-hosted by Japanese Nuclear Data Committee of AESJ and North Kanto Branch of AESJ. In the symposium, a tutorial was given by Prof. Rykaczewski (ORNL) "New nuclear data from total absorption spectroscopy and beta-delayed neutron measurements", as well as six oral sessions, "Nuclear Physics and Nuclear Data" (two sessions), "Nuclear Theory and Nuclear Data", "Reactors" and "Nuclear Data and Their Applications" (two sessions). In addition, recent advances in experiment, theory, evaluation, benchmark, and application were presented in the poster session. The symposium had 79 participants, who contributed to very active and fruitful discussions. This report consists of 37 papers, including those of 14 oral and 23 poster presentations.

Journal Articles

First direct mass measurements of nuclides around $$Z$$ = 100 with a multireflection time-of-flight mass spectrograph

Ito, Yuta*; Schury, P.*; Wada, Michiharu*; Arai, Fumiya*; Haba, Hiromitsu*; Hirayama, Yoshikazu*; Ishizawa, Satoshi*; Kaji, Daiya*; Kimura, Sota*; Koura, Hiroyuki; et al.

Physical Review Letters, 120(15), p.152501_1 - 152501_6, 2018/04

 Times Cited Count:11 Percentile:3.78(Physics, Multidisciplinary)

Masses of $$^{246}$$Es, $$^{251}$$Fm and the transfermium nuclei $$^{249-252}$$Md, and $$^{254}$$No, produced by hot- and cold-fusion reactions, in the vicinity of the deformed $$N=152$$ neutron shell closure, have been directly measured using a multi-reflection time-of-flight mass spectrograph. The masses of $$^{246}$$Es and $$^{249,250,252}$$Md were measured for the first time. Using the masses of $$^{249,250}$$Md as anchor points for $$alpha$$ decay chains, the masses of heavier nuclei, up to $$^{261}$$Bh and $$^{266}$$Mt, were determined. These new masses were compared with theoretical global mass models and demonstrated to be in good agreement with macroscopic-microscopic models in this region. The empirical shell gap parameter $$delta_{2n}$$ derived from three isotopic masses was updated with the new masses and corroborate the existence of the deformed $$N=152$$ neutron shell closure for Md and Lr.

Journal Articles

Nihonium, and the next elements...

Sakurai, Hiroshi*; Shinohara, Atsushi*; Koura, Hiroyuki; Kamigaito, Osamu*; Morimoto, Koji*; Haba, Hiromitsu*; Enyo, Hideto*

Isotope News, (特別号2), p.2 - 14, 2018/01

no abstracts in English

Journal Articles

Improvement of gross theory of beta-decay on single particle treatment

Koura, Hiroyuki; Yoshida, Tadashi*; Tachibana, Takahiro*; Chiba, Satoshi*

JAEA-Conf 2017-001, p.205 - 210, 2018/01

no abstracts in English

Journal Articles

Cutting-edge studies on nuclear data for continuous and emerging need, 4; Nuclear chart; Magnificent landscape of nuclei

Koura, Hiroyuki; Minato, Futoshi; Iimura, Hideki

Nippon Genshiryoku Gakkai-Shi, 60(1), p.35 - 40, 2018/01

no abstracts in English

Journal Articles

Improvement of gross theory of beta-decay for application to nuclear data

Koura, Hiroyuki; Yoshida, Tadashi*; Tachibana, Takahiro*; Chiba, Satoshi*

EPJ Web of Conferences (Internet), 146, p.12003_1 - 12003_4, 2017/09

BB2016-0950.pdf:0.33MB

 Percentile:100

Journal Articles

Observation of doubly-charged ions of francium isotopes extracted from a gas cell

Schury, P.*; Wada, Michiharu*; Ito, Yuta*; Kaji, Daiya*; Haba, Hiromitsu*; Hirayama, Yoshikazu*; Kimura, Sota*; Koura, Hiroyuki; MacCormick, M.*; Miyatake, Hiroari*; et al.

Nuclear Instruments and Methods in Physics Research B, 407, p.160 - 165, 2017/06

 Times Cited Count:3 Percentile:27.27(Instruments & Instrumentation)

Various isotopes of Ac, Ra, Fr, and Rn were produced by fusion-evaporation reactions using a $$^{48}$$Ca beam. The energetic ions were stopped in and extracted from a helium gas cell. The extracted ions were identified using a multi-reflection time-of-fight mass spectrograph. In all cases, it was observed that the predominant charge state for the extracted ions, including the alkali Fr, was 2+.

Journal Articles

Improvement of the gross theory of $$beta$$ decay by inclusion of change in parity

Koura, Hiroyuki; Chiba, Satoshi*

Physical Review C, 95(6), p.064304_1 - 064304_6, 2017/06

AA2016-0436.pdf:0.78MB

 Times Cited Count:4 Percentile:30.79(Physics, Nuclear)

An improvement on the single-particle structure is carried out to a global $$beta$$-decay model, the gross theory. The gross theory is based on a consideration of the sum rule of the intensity of the $$beta$$-decay transition by using the strength function. This model gives reasonable results of $$beta$$-decay rates and delayed neutron in the entire nuclear mass region. An attempt is made to improve the gross theory of nuclear $$beta$$-decay on consideration of the change of parity on the single-particle level of ground-state nuclei. In this treatment, the nuclear matrix elements are suppressed when the parity between single neutron and proton levels is different for the allowed transition. The assignment of parity is done by using the Woods-Saxon type single-particle potential. The discrepancies from experimental half-lives, which appeared in the vicinity on the magic number of neutrons and protons, are systematically improved in the nuclear mass region.

Journal Articles

Nuclear chemistry; With nuclear chart

Koura, Hiroyuki

Kagaku To Kyoiku, 65(3), p.108 - 111, 2017/03

no abstracts in English

Journal Articles

Journal Articles

First online multireflection time-of-flight mass measurements of isobar chains produced by fusion-evaporation reactions; Toward identification of superheavy elements via mass spectroscopy

Schury, P.*; Wada, Michiharu*; Ito, Yuta*; Kaji, Daiya*; Arai, Fumiya*; MacCormick, M.*; Murray, I.*; Haba, Hiromitsu*; Jeong, S.*; Kimura, Sota*; et al.

Physical Review C, 95(1), p.011305_1 - 011305_6, 2017/01

AA2016-0638.pdf:0.71MB

 Times Cited Count:10 Percentile:8.11(Physics, Nuclear)

Using a multireflection time-of-flight mass spectrograph located after a gas cell coupled with the gas-filled recoil ion separator GARIS-II, the masses of several $$alpha$$-decaying heavy nuclei were directly and precisely measured. The nuclei were produced via fusion-evaporation reactions and separated from projectilelike and targetlike particles using GARIS-II before being stopped in a helium-filled gas cell. Time-of-flight spectra for three isobar chains, $$^{204}$$Fr-$$^{204}$$Rn-$$^{204}$$At-$$^{204}$$Po, $$^{205}$$Fr- $$^{205}$$Rn-$$^{205}$$At-$$^{205}$$Po-$$^{205}$$Bi, and $$^{206}$$Fr-$$^{206}$$Rn-$$^{206}$$At, were observed. Precision atomic mass values were determined for $$^{204-206}$$Fr, $$^{204,205}$$Rn, and $$^{204,205}$$At. Identifications of $$^{205}$$Bi, $$^{204,205}$$Po, $$^{206}$$Rn, and $$^{206}$$At were made with N$$leq$$10 detected ions, representing the next step toward use of mass spectrometry to identify exceedingly low-yield species such as superheavy element ions.

JAEA Reports

Proceedings of the 2015 Symposium on Nuclear Data; November 19-20, 2015, Ibaraki Quantum Beam Research Center, Tokai-mura, Ibaraki, Japan

Iwamoto, Osamu; Sanami, Toshiya*; Kunieda, Satoshi; Koura, Hiroyuki; Nakamura, Shoji

JAEA-Conf 2016-004, 247 Pages, 2016/09

JAEA-Conf-2016-004.pdf:26.48MB

The 2015 Symposium on Nuclear Data was held at Ibaraki Quantum Beam Research Center, on November 19 and 20, 2015. The symposium was organized by the Nuclear Data Division of the Atomic Energy Society of Japan in cooperation with Nuclear Science and Engineering Center of Japan Atomic Energy Agency and North Kanto Branch of Atomic Energy Society of Japan. In the symposium, there were two tutorials, "Theory of Few-Body Systems and Recent Topics" and "Use of Covariance Data 2015" and four oral sessions, "Recent Research Topics", "Progress of AIMAC Project", "Present Status of JENDL Evaluated Files", and "Nuclear Data Applications". In addition, recent research progress on experiments, evaluation, benchmark and application was presented in a poster session. Among 99 participants, all presentations and following discussions were very active and fruitful. This report consists of total 46 papers including 13 oral and 33 poster presentations.

Journal Articles

Towards a novel laser-driven method of exotic nuclei extraction-acceleration for fundamental physics and technology

Nishiuchi, Mamiko*; Sakaki, Hironao*; Esirkepov, T. Zh.*; Nishio, Katsuhisa; Pikuz, T. A.*; Faenov, A. Ya.*; Skobelev, I. Yu.*; Orlandi, R.; Pirozhkov, A. S.*; Sagisaka, Akito*; et al.

Plasma Physics Reports, 42(4), p.327 - 337, 2016/04

 Times Cited Count:5 Percentile:42.53(Physics, Fluids & Plasmas)

A combination of a petawatt laser and nuclear physics techniques can crucially facilitate the measurement of exotic nuclei properties. With numerical simulations and laser-driven experiments we show prospects for the Laser-driven Exotic Nuclei extraction-acceleration method proposed in [M. Nishiuchi et al., Phys. Plasmas 22, 033107 (2015)]: a femtosecond petawatt laser, irradiating a target bombarded by an external ion beam, extracts from the target and accelerates to few GeV highly charged short-lived heavy exotic nuclei created in the target via nuclear reactions.

JAEA Reports

Improvement of WWW chart of the nuclides interface

Okamoto, Tsutomu; Minato, Futoshi; Koura, Hiroyuki; Iwamoto, Osamu

JAEA-Data/Code 2015-029, 30 Pages, 2016/03

JAEA-Data-Code-2015-029.pdf:1.81MB

The booklet "chart of the nuclides" is issued every 4 years since 1976 from Nuclear Data Center, JAEA. The chart of the nuclides for WWW (World Wide Web) was developed in 1999 in order to be available from internet browser. Internet connection speeds, browser functions and JavaScript libraries has, however, progressed at present compared with the internet technology in those days. In connection with the release of the 2014 edition of the chart of the nuclides, the interface of the WWW chart of the nuclides has been improved by introducing new internet technologies aiming at enhancing convenience on accessibilities via browsers. We introduced a scrolling screen that would make capabilities of easy screen movement on a map with the addition of the drag scrolling function. Considering smart phone access, the light-weight edition which introduced automatic switch was prepared. The new system results in reduction in access time and usefulness in mobile environment. The method of making figures of the chart was reconsidered due to addition of new decay schemes to the 2014 edition. SVG (Scalable Vector Graphics) was adopted so as to make figures easily. It is concluded that the accessibilities of WWW chart of the nuclides are substantially improved from the previous version by introducing the new technologies.

JAEA Reports

Proceedings of the 2014 Symposium on Nuclear Data; November 27-28, 2014, Conference hall, Hokkaido University, Sapporo Japan

Aikawa, Masayuki*; Iwamoto, Osamu; Ebata, Shuichiro*; Kunieda, Satoshi; Nakamura, Shoji; Koura, Hiroyuki

JAEA-Conf 2015-003, 332 Pages, 2016/03

JAEA-Conf-2015-003.pdf:30.22MB

The 2014 Symposium on Nuclear Data was held at Conference Hall, Hokkaido University, on November 27 and 28, 2014. The symposium was organized by the Nuclear Data Division of the Atomic Energy Society of Japan, Hokkaido Branch of the Atomic Energy Society of Japan, and Nuclear Reaction Data Centre, Faculty of Science, Hokkaido University in cooperation with Nuclear Science and Engineering Directorate of Japan Atomic Energy Agency. In the symposium, there were two tutorials, "Cross section measurement strategy for long lived fission product" and "Physics and Nuclear Data in Radiation Therapy" and four sessions, "A Neutron TOF Measurement Instrument desired by Nuclear Data Community", "Recent Topics", "Application of Nuclear Data", and "Nuclear Theory and Nuclear Data". In addition, recent research progress on experiments, evaluation, benchmark and application was presented in a poster session. Among 88 participants, all presentations and following discussions were very active and fruitful. This report consists of total 62 papers including 2 tutorials, 16 oral and 44 poster presentations.

Journal Articles

Compilation for chart of the nuclides 2014; A Comprehensive decay data

Koura, Hiroyuki; Katakura, Junichi*; Tachibana, Takahiro*; Minato, Futoshi

JAEA-Conf 2015-003, p.147 - 152, 2016/03

A chart of the nuclides 2014 version is now preparing to be published from JAEA. This will be the latest successive version of the chart since 1977, and continues every (approximately) four years until 2010. These charts include decay data of isotopes as half-lives, decay modes, and some isomeric states. In addition, the periodic table of elements, fundamental physical constants, thermal neutron capture and fission cross sections are tabulated. The latest version is now compiled with recent experimental data until the end of June in 2014. In the compilation process, we improved in the following parts: (1) Neutron or proton-unbound nuclei in the lighter region. (2) Drawing the neutron and proton-drip lines, and a boundary line of $$beta$$-delayed neutron emission. (3) 1- or 2-proton-emission theoretical half-lives are added for unmeasured nuclei in addition to original three partial half-lives of $$alpha$$-decay, $$beta$$-decay and spontaneous fission. We compiled totally 3150 nuclides, which were experimental identified including 2914 life-measured nuclei. We will show overview of the chart with some statistics and examples.

Journal Articles

A Comprehensive approach to determination of nuclear data of unstable nuclei

Chiba, Satoshi*; Nishio, Katsuhisa; Aritomo, Yoshihiro*; Koura, Hiroyuki; Iwamoto, Osamu; Makii, Hiroyuki; Nishinaka, Ichiro*; Hirose, Kentaro

EPJ Web of Conferences (Internet), 106, p.04004_1 - 04004_9, 2016/02

 Percentile:100

Journal Articles

Decay properties of new isotopes $$^{234}$$Bk and $$^{230}$$Am, and even-even nuclides $$^{234}$$Cm and $$^{230}$$Pu

Kaji, Daiya*; Morimoto, Koji*; Haba, Hiromitsu*; Ideguchi, Eiji*; Koura, Hiroyuki; Morita, Kosuke*

Journal of the Physical Society of Japan, 85(1), p.015002_1 - 015002_2, 2016/01

 Times Cited Count:7 Percentile:29.51(Physics, Multidisciplinary)

A neutron deficient berkelium isotope of $$^{234}$$Bk produced via the $$^{197}$$Au($$^{40}$$Ar, 3n) reaction and the daughter product of $$^{230}$$Am were newly identified. Alpha-decay energies of eleven $$^{234}$$Bk were found in 7.62 - 7.96 MeV, and six fission events correlated with $$alpha$$-decay of $$^{234}$$Bk were observed. The half-lives of $$^{234}$$Bk and $$^{230}$$Am were determined to be 19$$^{+6}_{-4}$$ s and 32$$^{+22}_{-9}$$ s, respectively. The $$^{234}$$Cm followed by $$beta$$-decay of $$^{234}$$Bk was also identified.

186 (Records 1-20 displayed on this page)