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Journal Articles

How different is the core of $$^{25}$$F from $$^{24}$$O$$_{g.s.}$$ ?

Tang, T. L.*; Uesaka, Tomohiro*; Kawase, Shoichiro; Beaumel, D.*; Dozono, Masanori*; Fujii, Toshihiko*; Fukuda, Naoki*; Fukunaga, Taku*; Galindo-Uribarri. A.*; Hwang, S. H.*; et al.

Physical Review Letters, 124(21), p.212502_1 - 212502_6, 2020/05

 Times Cited Count:0 Percentile:100(Physics, Multidisciplinary)

The structure of a neutron-rich $$^{25}$$F nucleus is investigated by a quasifree ($$p,2p$$) knockout reaction. The sum of spectroscopic factors of $$pi 0d_{5/2}$$ orbital is found to be 1.0 $$pm$$ 0.3. The result shows that the $$^{24}$$O core of $$^{25}$$F nucleus significantly differs from a free $$^{24}$$O nucleus, and the core consists of $$sim$$35% $$^{24}$$O$$_{rm g.s.}$$, and $$sim$$65% excited $$^{24}$$O. The result shows that the $$^{24}$$O core of $$^{25}$$F nucleus significantly differs from a free $$^{24}$$O nucleus. The result may infer that the addition of the $$0d_{5/2}$$ proton considerably changes the neutron structure in $$^{25}$$F from that in $$^{24}$$O, which could be a possible mechanism responsible for the oxygen dripline anomaly.

Journal Articles

Shell structure of the neutron-rich isotopes $$^{69,71,73}$$Co

Lokotko, T.*; Leblond, S.*; Lee, J.*; Doornenbal, P.*; Obertelli, A.*; Poves, A.*; Nowacki, F.*; Ogata, Kazuyuki*; Yoshida, Kazuki; Authelet, G.*; et al.

Physical Review C, 101(3), p.034314_1 - 034314_7, 2020/03

 Times Cited Count:0 Percentile:100(Physics, Nuclear)

The structures of the neutron-rich $$^{69,71,73}$$Co isotopes were investigated via ($$p,2p$$) knockout reactions at the Radioactive Isotope Beam Factory, RIKEN. Level schemes were reconstructed using the $$gamma-gamma$$ coincidence technique, with tentative spin-parity assignments based on the measured inclusive and exclusive cross sections. Comparison with shell-model calculations suggests coexistence of spherical and deformed shapes at low excitation energies in the $$^{69,71,73}$$Co isotopes.

Journal Articles

Shell evolution of $$N$$ = 40 isotones towards $$^{60}$$Ca; First spectroscopy of $$^{62}$$Ti

Cort$'e$s, M. L.*; Rodriguez, W.*; Doornenbal, P.*; Obertelli, A.*; Holt, J. D.*; Lenzi, S. M.*; Men$'e$ndez, J.*; Nowacki, F.*; Ogata, Kazuyuki*; Poves, A.*; et al.

Physics Letters B, 800, p.135071_1 - 135071_7, 2020/01

 Times Cited Count:2 Percentile:25.8(Astronomy & Astrophysics)

Excited states in the $$N$$ = 40 isotone $$^{62}$$Ti were populated via the $$^{63}$$V($$p$$,$$2p$$)$$^{62}$$Ti reaction at $$sim$$200 MeV/nucleon at the Radioactive Isotope Beam Factory and studied using $$gamma$$-ray spectroscopy. The energies of the $$2_1^+ rightarrow 0_{rm gs}^+$$ and $$4_1^+ rightarrow 2_1^+$$ transitions, observed here for the first time, indicate a deformed Ti ground state. These energies are increased compared to the neighboring $$^{64}$$Cr and $$^{66}$$Fe isotones, suggesting a small decrease of quadrupole collectivity. The present measurement is well reproduced by large-scale shell-model calculations based on effective interactions, while ab initio and beyond mean-field calculations do not yet reproduce our findings.

Journal Articles

High-rate performance of a time projection chamber for an H-dibaryon search experiment at J-PARC

Kim, S. H.*; Ichikawa, Yudai; Sako, Hiroyuki; Hasegawa, Shoichi; Hayakawa, Shuhei*; Nanamura, Takuya*; Sato, Susumu; Tanida, Kiyoshi; Yoshida, Junya; 11 iof others*

Nuclear Instruments and Methods in Physics Research A, 940, p.359 - 370, 2019/10

 Times Cited Count:2 Percentile:28.85(Instruments & Instrumentation)

Journal Articles

Comparison of heavy-ion transport simulations; Collision integral with pions and $$Delta$$ resonances in a box

Ono, Akira*; Xu, J.*; Colonna, M.*; Danielewicz, P.*; Ko, C. M.*; Tsang, M. B.*; Wang, Y,-J.*; Wolter, H.*; Zhang, Y.-X.*; Chen, L.-W.*; et al.

Physical Review C, 100(4), p.044617_1 - 044617_35, 2019/10

 Times Cited Count:12 Percentile:4.7(Physics, Nuclear)

International comparison of heavy-ion induced reaction models were discussed in the international conference "Transport2017" held in April 2017. Owing to their importance for safety assessment of heavy-ion accelerators and dosimetry of astronauts, various models to simulate heavy-ion induced reaction models are developed. This study is intended to clarify the difference among them to pinpoint their problems. In the comparison study, 320 protons and neutrons were packed in a 20-fm-large cube to calculate the number and energies of collisions during the time evolution. The author contributed to this study by running calculation using JQMD (JAERI Quantum Molecular Dynamics). This study showed that time step in the calculation is one of the biggest causes of the discrepancies. For example, the calculation by JQMD comprises 1-fm/c time steps, each of which is composed of transport, scattering and decay phases. Therefore a sequence of scattering, and decay followed by another scattering in 1 fm/c cannot be considered. Moreover, in JQMD particles are labeled by sequential numbers and scattering reactions are simulated by the order. Therefore scattering between low ID numbers, that between high ID numbers and that between the first (low ID) pair is overlooked in JQMD. Above indications obtained in this study must be kept in our mind for future JQMD upgrades.

Journal Articles

Quasifree neutron knockout from $$^{54}$$Ca corroborates arising $$N=34$$ neutron magic number

Chen, S.*; Lee, J.*; Doornenbal, P.*; Obertelli, A.*; Barbieri, C.*; Chazono, Yoshiki*; Navr$'a$til, P.*; Ogata, Kazuyuki*; Otsuka, Takaharu*; Raimondi, F.*; et al.

Physical Review Letters, 123(14), p.142501_1 - 142501_7, 2019/10

 Times Cited Count:5 Percentile:16.24(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Beam commissioning of muon beamline using negative hydrogen ions generated by ultraviolet light

Nakazawa, Yuga*; Bae, S.*; Choi, H.*; Choi, S.*; Iijima, Toru*; Iinuma, Hiromi*; Kawamura, Naritoshi*; Kitamura, Ryo; Kim, B.*; Ko, H. S.*; et al.

Nuclear Instruments and Methods in Physics Research A, 937, p.164 - 167, 2019/09

 Times Cited Count:1 Percentile:53.3(Instruments & Instrumentation)

A muon linac is under development for the precise measurement of the muon anomalous magnetic moment ($$g$$-2) and electric dipole moment (EDM) with a reaccelerated thermal muon beam. An H$$^-$$ source driven by an ultraviolet light has been developed for the muon acceleration experiment. Prior to the acceleration experiment, a beamline commissioning was performed using this H$$^-$$ beam, since the accelerated muon intensity is very low. We successfully measured the magnetic rigidity, which is essential for identifying the accelerated muons. This H$$^-$$ source is capable of utilizing as a general-purpose beam source for other beamline.

Journal Articles

Neutron-induced damage simulations; Beyond defect production cross-section, displacement per atom and iron-based metrics

Sublet, J.-Ch.*; Bondarenko, I. P.*; Bonny, G.*; Conlin, J. L.*; Gilbert, M. R.*; Greenwood, L. R.*; Griffin, P. J.*; Helgesson, P.*; Iwamoto, Yosuke; Khryachkov, V. A.*; et al.

European Physical Journal Plus (Internet), 134(7), p.350_1 - 350_50, 2019/07

 Times Cited Count:3 Percentile:50.07(Physics, Multidisciplinary)

Nuclear reaction with nuclear data is the origin of defects produced by cascade damage in irradiated materials. Therefore, it is important to consider nuclear reaction correctly for calculations of the damage energy of Primary Knock on Atom (PKA) and the number of Displacement Per Atom (DPA). Here, radiation damage metrics considering nuclear reaction enables us to simulate transport of each defect and clustering defects in the irradiated material. This paper reviews the theory of nuclear reaction and damage energy and describes the latest methodologies about uncertainty propagation and quantification in nuclear data and damage calculations based on molecular dynamics.

Journal Articles

Activities of the GIF safety and operation project of sodium-cooled fast reactor systems

Yamano, Hidemasa; Vasile, A.*; Kang, S.-H.*; Summer, T.*; Tsige-Tamirat, H.*; Wang, J.*; Ashurko, I.*

Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 7 Pages, 2019/05

The Generation IV (GEN-IV) international forum is a framework for international co-operation in research and development for the next generation of nuclear energy systems. Within the GEN-IV sodium-cooled fast reactor (SFR) system arrangement, the SFR Safety and Operation (SO) project addresses the areas of safety technology and reactor operation technology developments. The aims of the SO project include (1) analyses and experiments that support establishing safety approaches and validating performance of specific safety features, (2) development and verification of computational tools and validation of models employed in safety assessment and facility licensing, and (3) acquisition of reactor operation technology, as determined largely from experience and testing in operating SFR plants. The tasks in the SO topics are categorized into the following three work packages (WP): WP-SO-1 "Methods, Models and Codes", WP-SO-2 "Experimental Programs and Operational Experience", and WP-SO-3 "Studies of Innovative Design and Safety Systems". This paper reports recent activities within the SO project.

Journal Articles

Population of nuclides with Z$$ge$$98 in multi-nucleon transfer reactions of $$^{48}$$Ca+$$^{248}$$Cm

Devaraja, H. M.*; Heinz, S.*; Beliuskina, O.*; Hofmann, S.*; Hornung, C.*; M$"u$nzenberg, G.*; Ackermann, D.*; Gupta, M.*; Gambhir, Y. K.*; Henderson, R. A.*; et al.

European Physical Journal A, 55(2), p.25_1 - 25_9, 2019/02

 Times Cited Count:4 Percentile:35.18(Physics, Nuclear)

Journal Articles

Development of a microchannel plate based beam profile monitor for a re-accelerated muon beam

Kim, B.*; Bae, S.*; Choi, H.*; Choi, S.*; Kawamura, Naritoshi*; Kitamura, Ryo*; Ko, H. S.*; Kondo, Yasuhiro; Mibe, Tsutomu*; Otani, Masashi*; et al.

Nuclear Instruments and Methods in Physics Research A, 899, p.22 - 27, 2018/08

 Times Cited Count:4 Percentile:26.29(Instruments & Instrumentation)

A beam profile monitor (BPM) based on a microchannel plate has been developed for muon beams with low transverse momentum for the measurement of the muon anomalous magnetic moment and electric dipole moment at high precision, with capability of diagnosing muon beams of kinetic energy range from a few keV to 4 MeV. The performance of the BPM has been evaluated using a surface muon beam at J-PARC and additionally with an ultraviolet (UV) light source. It has been confirmed that the BPM has a dynamic range from a few to 10$$^4$$ muons per bunch without saturation. The spatial resolution of the BPM has been estimated to be less than 0.30 mm. The positron background from muon decays is an obstacle in muon beam profile monitoring and a partial discrimination of the positrons has been achieved under discrete particle conditions.

Journal Articles

First muon acceleration using a radio-frequency accelerator

Bae, S.*; Choi, H.*; Choi, S.*; Fukao, Yoshinori*; Futatsukawa, Kenta*; Hasegawa, Kazuo; Iijima, Toru*; Iinuma, Hiromi*; Ishida, Katsuhiko*; Kawamura, Naritoshi*; et al.

Physical Review Accelerators and Beams (Internet), 21(5), p.050101_1 - 050101_6, 2018/05

 Times Cited Count:9 Percentile:13.16(Physics, Nuclear)

Muons have been accelerated by using a radio-frequency accelerator for the first time. Negative muonium atoms (Mu$$^{-}$$), which are bound states of positive muons and two electrons, are generated from through the electron capture process in an aluminum degrader. The generated Mu$$^{-}$$'s are initially electrostatically accelerated and injected into a radio-frequency quadrupole linac (RFQ). In the RFQ, the Mu$$^{-}$$'s are accelerated to 89 keV. The accelerated Mu$$^{-}$$'s are identified by momentum measurement and time of flight. This compact muon linac opens the door to various muon accelerator applications including particle physics measurements and the construction of a transmission muon microscope.

Journal Articles

Comparison of heavy-ion transport simulations; Collision integral in a box

Zhang, Y.-X.*; Wang, Y,-J.*; Colonna, M.*; Danielewicz, P.*; Ono, Akira*; Tsang, M. B.*; Wolter, H.*; Xu, J.*; Chen, L.-W.*; Cozma, D.*; et al.

Physical Review C, 97(3), p.034625_1 - 034625_20, 2018/03

 Times Cited Count:45 Percentile:0.74(Physics, Nuclear)

International comparison of heavy-ion induced reaction models were discussed in the international conference "Transport2017" held in April 2017. Owing to their importance for safety assessment of heavy-ion accelerators and dosimetry of astronauts, various models to simulate heavy-ion induced reaction models are developed. This study is intended to clarify the difference among them to pinpoint their problems. In the comparison study, 320 protons and 320 neutrons were packed in a 20-fm-large cube to calculate the number of particle-particle collisions as well as the energies of collisions during the time evolution. In addition to the calculation, their algorithms were compared. The author contributed to this study by running calculation using JQMD (JAERI Quantum Molecular Dynamics). The results were compared with those calculated by the other 15 codes from over the world. Algorithm comparison showed that JQMD calculates collision probabilities from protons at first and collisions by neutrons are simulated later, which might be unreasonable. On the other hand, it was clarified that the calculation by JQMD agrees with those by the others. Despite the fact that some codes deviate from the average by a factor of 2, JQMD exhibited stable performance.

Journal Articles

Exotic hadrons from heavy ion collisions

Cho, S.*; Hyodo, Tetsuo*; Jido, Daisuke*; Ko, C. M.*; Lee, S. H.*; Maeda, Saori*; Miyahara, Kenta*; Morita, Kenji*; Nielsen, M.*; Onishi, Akira*; et al.

Progress in Particle and Nuclear Physics, 95, p.279 - 322, 2017/07

AA2016-0538.pdf:0.65MB

 Times Cited Count:36 Percentile:14.73(Physics, Nuclear)

With upgraded detectors at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC), it has become possible to measure hadrons beyond their ground states in high energy heavy ion collisions. Therefore, heavy ion collisions provide a new method for studying exotic hadrons that are either molecular states made of various hadrons or compact system consisting of muliquarks. Because their structures are related to the fundamental properties of Quantum Chromodynamics (QCD), studying exotic hadrons is currently one of the most active areas of research in hadron physics. The present review is a summary of the current understanding of a selected set of exotic candidate particles that can be potentially measured in heavy ion collisions.

Journal Articles

Recent activities of the safety and operation project of the sodium-cooled fast reactor in the Generation IV International Forum

Vasile, A.*; Ren, L.*; Fanning, T.*; Tsige-Tamirat, H.*; Yamano, Hidemasa; Kang, S.-H.*; Ashurko, I.*

Proceedings of International Conference on Fast Reactors and Related Fuel Cycles; Next Generation Nuclear Systems for Sustainable Development (FR-17) (USB Flash Drive), 15 Pages, 2017/06

The tasks in the Safety and Operation (SO) topics are categorized into the following three work packages (WP): WP-SO-1 Methods, Models and codes is devoted to the development of tools for the evaluation of safety, WP-SO-2 Experimental Programs and Operational Experiences includes the operation, maintenance and testing experiences in experimental facilities and SFRs (e.g., Monju, Phenix, BN-600 and CEFR), and WP-SO-3 Studies of Innovative Design and Safety Systems relates to safety technologies for GEN-IV reactors such as active and passive safety systems and other specific design features. In this paper, recent activities in the SO project are described.

Journal Articles

$$gamma$$ decay of unbound neutron-hole states in $$^{133}$$Sn

Vaquero, V.*; Jungclaus, A.*; Doornenbal, P.*; Wimmer, K.*; Gargano, A.*; Tostevin, J. A.*; Chen, S.*; N$'a$cher, E.*; Sahin, E.*; Shiga, Yoshiaki*; et al.

Physical Review Letters, 118(20), p.202502_1 - 202502_5, 2017/05

 Times Cited Count:13 Percentile:17.71(Physics, Multidisciplinary)

Journal Articles

Baryon spectroscopy in $$(pi,2pi)$$ reactions with 10$$^{6}$$Hz pion beams at J-PARC

Sako, Hiroyuki; Hasegawa, Shoichi; Hosomi, Kenji; Ichikawa, Yudai; Imai, Kenichi; Hicks, K.*; Ahn, J. K.*; Kim, S. H.*; Lee, J. W.*; Hwang, S. H.*

Proceedings of Science (Internet), 5 Pages, 2017/05

Although baryon resonances have been studied for a long time, our knowledge on their properties are still limited. Recently a Dynamical-Couple Channel (DCC) model shows there are significant contributions of $$(pi,2pi)$$ reactions to these baryon resonances. However, there are only 240 thousand events of $$(pi, 2pi)$$ reaction data measured in 1970's. Thus, we proposed an experiment E45 to study baryon resonances in $$(pi,2pi)$$ reaction utilizing $$10^6$$ Hz $$pi$$ beams at J-PARC. We aim at clarifying most of baryon mass levels. We measure these reactions in a large acceptance Time Projection Chamber inside a Helmholtz dipole magnet. We will measure these reactions in small momentum steps over a large beam momentum range and perform partial wave analysis to extract properties of each resonance. In this presentation, we will show the experimental design, expected results in simulations, and the status of the detectors.

Journal Articles

Modelling of marine radionuclide dispersion in IAEA MODARIA program; Lessons learnt from the Baltic Sea and Fukushima scenarios

Peri$'a$$~n$ez, R.*; Bezhenar, R.*; Brovchenko, I.*; Duffa, C.*; Iosjpe, M.*; Jung, K. T.*; Kobayashi, Takuya; Lamego, F.*; Maderich, V.*; Min, B. I.*; et al.

Science of the Total Environment, 569-570, p.594 - 602, 2016/11

 Times Cited Count:14 Percentile:36.47(Environmental Sciences)

State-of-the art dispersion models were applied to simulate $$^{137}$$Cs dispersion from Chernobyl Nuclear Power Plant disaster fallout in the Baltic Sea and from Fukushima Daiichi Nuclear Plant releases in the Pacific Ocean after the 2011 tsunami. Models were of different nature, from box to full three-dimensional models, and included water/sediment interactions. Agreement between models was very good in the Baltic. In the case of Fukushima, results from models could be considered to be in acceptable agreement only after a model harmonization process consisting of using exactly the same forcing (water circulation and parameters) in all models. It was found that the dynamics of the considered system (magnitude and variability of currents) was essential in obtaining a good agreement between models. The difficulties in developing operative models for decision-making support in these dynamic environments were highlighted.

Journal Articles

Review of even element super-heavy nuclei and search for element 120

Hofmann, S.*; Heinz, S.*; Mann, R.*; Maurer, J.*; M$"u$nzenberg, G.*; Antalic, S.*; Barth, W.*; Burkhard, K. G.*; Dahl, L.*; Eberhardt, K.*; et al.

European Physical Journal A, 52(6), p.180_1 - 180_34, 2016/06

 Times Cited Count:82 Percentile:9.09(Physics, Nuclear)

Journal Articles

Activities of the safety and operation project for the international research and development of the sodium-cooled fast reactor in the Generation IV international forum

Sakai, Takaaki; Ren, L.*; Tsige-Tamirat, H.*; Vasile, A.*; Kang, S.-H.*; Ashurko, Y.*; Fanning, T.*

Proceedings of 24th International Conference on Nuclear Engineering (ICONE-24) (DVD-ROM), 7 Pages, 2016/06

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