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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:1 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

Restoration of the natural $$E(1/2^+_1)-E(3/2^+_1)$$ energy splitting in odd-K isotopes towards $$N=40$$

Sun, Y. L.*; Obertelli, A.*; Doornenbal, P.*; Barbieri, C.*; Chazono, Yoshiki*; Duguet, T.*; Liu, H. N.*; Navr$'a$til, P.*; Nowacki, F.*; Ogata, Kazuyuki*; et al.

Physics Letters B, 802, p.135215_1 - 135215_7, 2020/03

 Times Cited Count:2 Percentile:27.79(Astronomy & Astrophysics)

no abstracts in English

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:11.68(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

Toward a reliable description of ($$p$$,$$pN$$) reactions in the distorted-wave impulse approximation

Phuc, N. T. T.*; Yoshida, Kazuki; Ogata, Kazuyuki*

Physical Review C, 100(6), p.064604_1 - 064604_8, 2019/12

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

Our goal is to investigate the effects of various corrections and uncertainties within the standard distorted-wave impulse approximation (DIWA) formalism on the ($$p$$,$$pN$$) cross sections. We analyze the ($$p$$,$$2p$$) and ($$p$$,$$pn$$) reactions data measured at the R3B/LAND setup at GSI for carbon, nitrogen and oxygen isotopes in the incident energy range of 300-450 MeV/u. Cross sections and reduction factors are calculated by the DWIA method. We have found that including the nonlocality corrections and M$$o$$ller factor affects the cross sections considerably. The proton-neutron asymmetry dependence of reduction factors extracted by the DWIA calculation is very weak and consistent with those given by other reaction methods and ab initio structure calculations. They also suggest that some higher-order effects, which is essential for an accurate cross section description at large recoil momentum, is missing in the current DWIA and other reaction models.

Journal Articles

Quantitative description of the $$^{20}$$Ne($$p$$,$$palpha$$)$$^{16}$$O reaction as a means of probing the surface $$alpha$$ amplitude

Yoshida, Kazuki; Chiba, Yohei*; Kimura, Masaaki*; Taniguchi, Yasutaka*; Enyo, Yoshiko*; Ogata, Kazuyuki*

Physical Review C, 100(4), p.044601_1 - 044601_6, 2019/10

 Times Cited Count:1 Percentile:60.45(Physics, Nuclear)

The proton-induced $$alpha$$ knockout reaction is one of the reaction probes for the $$alpha$$ clustering. However, it was reported that the theoretical description of the reaction cannot reproduce experimental data. In this work, we describe the $$^{20}$$Ne($$p$$,$$palpha$$)$$^{16}$$O reaction within the distorted wave impulse approximation with a $$alpha$$-$$^{16}$$O cluster wave function constructed by the antisymmetrized molecular dynamics. We show that the $$^{20}$$Ne($$p$$,$$palpha$$)$$^{16}$$O cross section is quantitatively well reproduced by the present framework without any adjustable parameters. This success demonstrates that the proton-induced $$alpha$$ knockout reaction is a quantitative probe for the $$alpha$$ clustering.

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:6 Percentile:18.18(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Direct probing of the cluster structure in $$^{12}$$Be via the $$alpha$$-knockout reaction

Lyu, M.*; Yoshida, Kazuki; Enyo, Yoshiko*; Ogata, Kazuyuki*

Physical Review C, 99(6), p.064610_1 - 064610_9, 2019/06

 Times Cited Count:1 Percentile:60.45(Physics, Nuclear)

Our objective is to provide direct probing of the $$alpha$$-cluster formation in the $$^{12}$$Be target through associating the structure information obtained by a microscopic theory with the experimental observables of $$alpha$$-knockout reactions. We formulate a new wave function of the Tohsaki-Horiuchi-Schuck-R$"o$pke type for the structure of $$^{12}$$Be and adopt it to the distorted wave impulse approximation framework for the knockout reaction calculation. We reproduced the low-lying spectrum of $$^{12}$$Be, and the knockout cross section is theoretically predicted.

Journal Articles

Nuclear structure of $$^{76}$$Ni from the ($$p$$,$$2p$$) reaction

Elekes, Z.*; Kripk$'o$, $'A$*; Sohler, D.*; Sieja, K.*; Ogata, Kazuyuki*; Yoshida, Kazuki; Doornenbal, P.*; Obertelli, A.*; Authelet, G.*; Baba, Hidetada*; et al.

Physical Review C, 99(1), p.014312_1 - 014312_7, 2019/01

 Times Cited Count:3 Percentile:24.4(Physics, Nuclear)

The nuclear structure of the $$^{76}$$Ni nucleus was investigated by ($$p$$,$$2p$$) reaction using a NaI(Tl) array to detect the deexciting prompt $$gamma$$ rays. A new transition with an energy of 2227 keV was identified by $$gamma gamma$$ and $$gamma gamma gamma$$ coincidences. Our shell-model calculations using the Lenzi, Nowacki, Poves, and Sieja interaction produced good candidates for the experimental proton hole states in the observed energy region, and the theoretical cross sections showed good agreement with the experimental values. Although we could not assign all the experimental states to the theoretical ones unambiguously, the results are consistent with a reasonably large Z = 28 shell gap for nickel isotopes in accordance with previous studies.

Journal Articles

Investigation of $$alpha$$ clustering with knockout reactions

Yoshida, Kazuki; Ogata, Kazuyuki*; Kanada-En'yo, Yoshiko*

Physical Review C, 98(2), p.024614_1 - 024614_6, 2018/08

 Times Cited Count:5 Percentile:29.75(Physics, Nuclear)

In $$alpha$$ clustering studies, it is very important to probe the $$alpha$$ cluster amplitude at nuclear surface since $$alpha$$ spectroscopic factor is not necessarily a direct measure of the $$alpha$$ clustering. We consider $$^{20}$$Ne($$p$$,$$palpha$$)$$^{16}$$O and $$^{120}$$Sn($$p$$,$$palpha$$)$$^{116}$$Cd at 100 - 400 MeV within the distorted wave impulse approximation (DWIA) framework. We introduce a $textit{masking function}$ which shows how the reaction amplitude in the nuclear interior is suppressed and defines the probed region of the $$alpha$$ cluster wave function. It is clearly shown by means of the masking function that thanks to the absorption of distorting potentials, the $$alpha$$ knockout reaction probes the $$alpha$$ cluster amplitude in the nuclear surface region, which is the direct measure of well-developed $$alpha$$ cluster states.

Journal Articles

Theoretical model analysis of $$(d,xn)$$ reactions on $$^7$$Li at 25, 40, and 102 MeV

Sadamatsu, Hiroki*; Nakayama, Shinsuke; Watanabe, Yukinobu*; Iwamoto, Osamu; Ogata, Kazuyuki*

JAEA-Conf 2017-001, p.135 - 140, 2018/01

In recent years, the demand for intense neutron sources has been increasing in various applications such as nuclear transmutation of high-level radioactive waste and medical radioisotopes production. Deuteron accelerator-based neutron sources are promised as one of the candidates. Therefore, we have developed a code system dedicated for the deuteron-induced reactions, called DEURACS. In the present work, we focus on deuteron-induced neutron production from $$^7$$Li target. The calculated double differential cross sections for $$(d,xn)$$ reactions at incident energies of 25, 40, and 102 MeV are compared with the measured ones, and the applicability of DEURACS is discussed.

Journal Articles

Development of a code system DEURACS for theoretical analysis and prediction of deuteron-induced reactions

Nakayama, Shinsuke; Kono, Hiroshi*; Watanabe, Yukinobu*; Iwamoto, Osamu; Ye, T.*; Ogata, Kazuyuki*

EPJ Web of Conferences, 146, p.12025_1 - 12025_4, 2017/09

 Times Cited Count:1 Percentile:25.31

Recently, intensive neutron sources using deuteron accelerator have been proposed for various applications. Accurate and comprehensive deuteron nuclear data library over wide ranges of target mass number and incident energy are indispensable for the design of deuteron accelerator neutron sources. Thus, we have developed an integrated code system dedicated for analysis and prediction of deuteron-induced reactions, which is called DEUteron-induced Reaction Analysis Code System (DEURACS). In the present work, the analysis of $$(d,xn)$$ reactions is extended to higher incident energy up to nearly 100 MeV and also DEURACS is applied to $$(d,xd)$$ reactions at 80 and 100 MeV. The DEURACS calculations reproduce the experimental double-differential cross sections for the $$(d,xn)$$ and $$(d,xd)$$ reactions well.

Journal Articles

Nuclear data evaluation of long-lived fission products; Microscopic vs. phenomenological optical potentials

Minato, Futoshi; Iwamoto, Osamu; Minomo, Kosho*; Ogata, Kazuyuki*; Iwamoto, Nobuyuki; Kunieda, Satoshi; Furutachi, Naoya

EPJ Web of Conferences, 146, p.12032_1 - 12032_4, 2017/09

 Times Cited Count:1 Percentile:25.31

Phenomenological optical potential is known to be able to describe the elastic scattering process. It is applied widely to the nuclear data evaluation of the cross section. Many kinds of the optical potential have been studied so far. However, the parameters in the phenomenological optical potentials are determined so as to reproduce existing experimental data, so that use of it for unmeasured nuclei such as neutron-rich nuclei is not necessarily reliable. Recently, a new optical potential derived from the microscopic effective reaction theory (MERT) was proposed. Since the formulation of MERT is based on the NN effective interaction, any parameterizations in the optical potential aren't needed. Therefore, it is capable of calculating nuclei whose scattering cross section isn't measured. We incorporate the optical potentials of MERT in code CCONE and start nuclear data evaluation of several nuclei. In this work, we discuss difference of cross sections evaluated by MERT's optical potentials and conventional phenomenological ones.

Journal Articles

Probing surface distributions of $$alpha$$ clusters in $$^{20}$$Ne via $$alpha$$-transfer reaction

Fukui, Tokuro; Taniguchi, Yasutaka*; Suhara, Tadahiro*; Kanada-En'yo, Yoshiko*; Ogata, Kazuyuki*

Journal of Physics; Conference Series, 863(1), p.012036_1 - 012036_3, 2017/07

 Times Cited Count:0 Percentile:100

Journal Articles

Analysis of $$(d,xn)$$ reactions on $$^{9}$$Be and $$^{12}$$C

Nakayama, Shinsuke; Kono, Hiroshi*; Watanabe, Yukinobu*; Iwamoto, Osamu; Ogata, Kazuyuki*

RCNP Annual Report 2016 (Internet), 2 Pages, 2017/05

We are conducting a theoretical research on deuteron-induced reaction together with Kyushu University and Research Center for Nuclear Physics (RCNP) of Osaka University. The research outcomes achieved in fiscal year 2016 are summarized as a part of the annual report of RCNP. In recent years, accelerator neutron sources using $$(d,xn)$$ reactions on light nuclei (Li, Be, C, etc.) are proposed for applications in various fields. Engineering design of such facilities requires accurate prediction of $$(d,xn)$$ reactions on light nuclei in a wide incident energy range. Therefore, we have developed a physics-based computational code system dedicated for deuteron-induced reactions, called DEURACS. In fiscal year 2016, we calculated double-differential neutron yields from deuteron bombardment on thick $$^{9}$$Be and $$^{12}$$C targets, and the calculation reproduced the experimental data quantitatively well in the incident energy range up to 50 MeV. From the results, it has been found that DEURACS can accurately predict $$(d,xn)$$ reactions on light nuclei in a wide incident energy range. In addition, component-by-component analysis has revealed that the nonelastic breakup reactions make the most dominant contribution to neutron production.

Journal Articles

Determination of the $$^8{rm B}(p,gamma)^9{rm C}$$ reaction rate through direct nuclear reaction theories

Fukui, Tokuro; Ogata, Kazuyuki*; Minomo, Kosho*; Yahiro, Masanobu*

JPS Conference Proceedings (Internet), 14, p.020513_1 - 020513_3, 2017/02

 Times Cited Count:0 Percentile:100

Journal Articles

Theoretical model analysis of $$(d,xn)$$ reactions on beryllium

Kono, Hiroshi*; Watanabe, Yukinobu*; Nakayama, Shinsuke; Iwamoto, Osamu; Ye, T.*; Ogata, Kazuyuki*

JAEA-Conf 2016-004, p.165 - 170, 2016/09

For engineering design of deuteron accelerator neutron sources, accurate nuclear data of deuteron-induced reactions on neutron converter (Li, Be, C, etc.) and accelerator structure material (Fe, Cr, Ni, etc.) are indispensable. Therefore we have developed a computational code system based on physics models dedicated for deuteron nuclear data evaluation. In the present study, we have analyzed the $$(d,xn)$$ reactions on beryllium at incident deuteron energies up to 65 MeV. Since there is a lot of experimental Thick Target Neutron Yields (TTNYs), double-differential $$(d,xn)$$ cross sections are calculated by the code system and then are converted to TTNYs. It is found that the calculated TTNYs reproduce the experimental ones fairly well except in the low neutron energy region.

Journal Articles

Asymmetry dependence of reduction factors from single-nucleon knockout of $$^{30}$$Ne at $$sim$$ 230 MeV/nucleon

Lee, J.*; Liu, H.*; Doornenbal, P.*; Kimura, Masaaki*; Minomo, Kosho*; Ogata, Kazuyuki*; Utsuno, Yutaka; Aoi, Nori*; Li, K.*; Matsushita, Masafumi*; et al.

Progress of Theoretical and Experimental Physics (Internet), 2016(8), p.083D01_1 - 083D01_7, 2016/08

AA2016-0230.pdf:0.16MB

 Times Cited Count:4 Percentile:53.75(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Theoretical model analysis of $$(d,xn)$$ reactions on $$^9$$Be and $$^{12}$$C at incident energies up to 50 MeV

Nakayama, Shinsuke; Kono, Hiroshi*; Watanabe, Yukinobu*; Iwamoto, Osamu; Ogata, Kazuyuki*

Physical Review C, 94(1), p.014618_1 - 014618_9, 2016/07

 Times Cited Count:14 Percentile:18.84(Physics, Nuclear)

Double-differential thick target neutron yields (TTNYs) from deuteron bombardment on thick Be and C targets are analyzed using the DEURACS (DEUteron-induced Reaction Analysis Code System). The calculated TTNYs reproduced the experimental ones quantitatively well in the incident energy range up to 50 MeV. In addition, it was found that the proton stripping reaction makes the most dominant contribution to neutron production. From the analysis, we conclude that the DEURACS is applicable to $$(d,xn)$$ reactions and modeling of the stripping reaction is essential to predict neutron production yields accurately.

Journal Articles

Modelling and analysis of nucleon emission from deuteron-induced reactions at incident energies up to 100 MeV

Nakayama, Shinsuke; Kono, Hiroshi*; Watanabe, Yukinobu*; Iwamoto, Osamu; Ye, T.*; Ogata, Kazuyuki*

EPJ Web of Conferences, 122, p.04004_1 - 04004_9, 2016/06

 Times Cited Count:4 Percentile:8.83

In recent years, accelerator neutron sources using deuteron-induced reactions on $$^7$$Li, $$^9$$Be, $$^{12}$$C, etc., are proposed for applications in various fields. Engineering design of such facilities requires deuteron nuclear data in a broad incident energy range. We have developed a computational code system dedicated for deuteron nuclear data evaluation in combination with some theoretical models. The code system has been applied to analyses of double-differential $$(d,xp)$$ cross sections for $$^{12}$$C, $$^{27}$$Al, and $$^{58}$$Ni at incident energies up to 100 MeV. On the other hand, there is few experimental double-differential $$(d,xn)$$ cross sections. Therefore, double-differential thick target neutron yields for light nuclei such as $$^9$$Be and $$^{12}$$C are calculated and compared with experimental data. The presentation will show the validation result of the present modelling for nucleon emissions from deuteron-induced reactions through comparison with available experimental data.

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