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Journal Articles

Conceptual study on parasitic low-energy RI beam production with in-flight separator BigRIPS and the first stopping examination for high-energy RI beams in the parasitic gas cell

Sonoda, Tetsu*; Katayama, Ichiro*; Wada, Michiharu*; Iimura, Hideki; Sonnenschein, V.*; Iimura, Shun*; Takamine, Aiko*; Rosenbusch, M.*; Kojima, Takao*; Ahn, D. S.*; et al.

Progress of Theoretical and Experimental Physics (Internet), 2019(11), p.113D02_1 - 113D02_12, 2019/11

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

An in-flight separator, BigRIPS, at RIBF in RIKEN provides each experiment with specific nuclides separated from many nuclides produced by projectile fragmentation or in-flight fission. In this process, nuclides other than separated ones are discarded on the slits in BigRIPS, although they include many nuclides interested from the view point of nuclear structure. In order to extract these nuclides for parasitic experiments, we are developing a method using laser ion-source (PALIS). A test experiment with $$^{78}$$Se beam from RIBF has been performed by using a gas cell set in BigRIPS. Unstable nuclides around $$^{67}$$Se were stopped in the gas cell in accordance with a calculation using LISE code. The stopping efficiency has been estimated to be about 30%. As a next step, we will establish the technique for extracting reaction products from the gas cell.

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:27.46(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

The Laser and optical system for the RIBF-PALIS experiment

Sonoda, Tetsu*; Iimura, Hideki; Reponen, M.*; Wada, Michiharu*; Katayama, Ichiro*; Sonnenschein, V.*; Takamatsu, Takahide*; Tomita, Hideki*; Kojima, Takao*

Nuclear Instruments and Methods in Physics Research A, 877, p.118 - 123, 2018/01

 Times Cited Count:3 Percentile:40.19(Instruments & Instrumentation)

In order to produce low-energy RI beams at RIKEN RIBF, a laser ion source, PALIS, is under construction. This ion source is based on resonance ionization of RI atoms captured in Ar gas. Because the ion source is located 70m away from lasers, we have developed an optical system for laser beam transport. This system can be controlled remotely when the ion source is not accessible because of high radiation level. The position of laser beam after transport is reasonably stable, and the transport efficiency is about 50%.

JAEA Reports

JAEA-Tokai tandem annual report 2013; April 1, 2013 - March 31, 2014

Department of Research Reactor and Tandem Accelerator

JAEA-Review 2016-025, 101 Pages, 2016/12


The JAEA-Tokai tandem accelerator complex has been used in various research fields such as nuclear science and material science by researchers not only of JAEA but also from universities, research institutes and industrial companies. This annual report covers developments of accelerators and research activities carried out using the tandem accelerator and superconducting booster from April 1, 2013 to March 31, 2014. Thirty-one summary reports were categorized into seven research/development fields:(1) accelerator operation and development, (2) nuclear structure, (3) nuclear reaction, (4) nuclear chemistry, (5) nuclear theory, (6) atomic physics and solid state physics (7) radiation effects in materials. This report also lists publications, meetings, personnel, committee members, cooperative researches and common use programs.

Journal Articles

Discovery of new magic number ${it via}$ in-beam $$gamma$$-ray spectroscopy

Takeuchi, Satoshi*; Steppenbeck, D.*; Utsuno, Yutaka

Nippon Butsuri Gakkai-Shi, 70(7), p.535 - 539, 2015/07

no abstracts in English

Journal Articles

Large-scale shell-model calculations for unnatural-parity high-spin states in neutron-rich Cr and Fe isotopes

Togashi, Tomoaki*; Shimizu, Noritaka*; Utsuno, Yutaka; Otsuka, Takaharu*; Homma, Michio*

Physical Review C, 91(2), p.024320_1 - 024320_12, 2015/02


 Times Cited Count:16 Percentile:18.12(Physics, Nuclear)

We perform large-scale shell-model calculations for unnatural-parity high-spin states in neutron-rich Cr and Fe isotopes with $$N$$ = 31-35. The excitation energies of the $$9/2^+_1$$ states for those odd-mass nuclei sharply decrease with the neutron number, which attracts much interest. In this study, we calculate those unnatural-parity states systematically using an effective interaction comprised of existing ones plus minimal modifications. The calculated energy levels excellently agree with experimental data. The deformations of those isotopes are analysed by using the wave functions obtained by the shell-model calculations. We show that prolate deformation dominates this region, contrary to the previous suggestion based on the $$9/2^+_1$$ isomeric level. It is demonstrated that the sharp decrease of the $$9/2^+_1$$ levels occurs due to the rising of the Fermi surface, but not due to the evolution of the $$g_{9/2}$$ single-particle level as suggested previously.

Journal Articles

Nature of isomerism in exotic sulfur isotopes

Utsuno, Yutaka; Shimizu, Noritaka*; Otsuka, Takaharu*; Yoshida, Toru*; Tsunoda, Yusuke*

Physical Review Letters, 114(3), p.032501_1 - 032501_5, 2015/01


 Times Cited Count:22 Percentile:16.31(Physics, Multidisciplinary)

In usual even-even nuclei, $$0^+_1$$, $$2^+_1$$, $$4^+_1cdots$$ states are known to be connected via strong $$E2$$ transitions. The recently observed $$4^+_1$$ state in the neutron-rich nucleus $$^{44}$$S has a strongly hindered $$E2$$ transition to the $$4^+_1$$ state. We report the origin of this strong hindrance in this paper. While shell-model calculations reproduce the hindrance, their many-body wave functions are too complicated for one to understand the nature. In this study, we introduce a novel method to obtain wave functions in the intrinsic frame by performing the variation after angular-momentum projection. The $$0^+_1$$, $$2^+_1$$ states are dominated by the usual $$K=0$$ state, whereas for the $$4+$$ level the $$K=4$$ state is lower than $$K=0$$ state, which causes the $$E2$$ hindrance. We also account for similar $$E2$$ hindrance in $$^{43}$$S in this framework. The $$4^+$$ level is the lightest-mass high-$$K$$ isomer ever found.

Journal Articles

Levels in $$^{127}$$La fed by the $$^{127}$$Ce beta-decay

Iimura, Hideki; Asai, Masato; Ichikawa, Shinichi; Katakura, Junichi; Magara, Masaaki; Osa, Akihiko; Oshima, Masumi; Shinohara, Nobuo; Yamamoto, Hiroshi*

European Physical Journal A, 23(1), p.33 - 39, 2005/01

 Times Cited Count:1 Percentile:84.8(Physics, Nuclear)

The low-lying levels in $$^{127}$$La have been studied through the $$beta$$-decay of $$^{127}$$Ce (${it T}$$$_{1/2}$$ = 29 s) produced by bombarding a $$^{nat}$$Mo target with a 185-MeV $$^{35}$$Cl beam. Reaction products were on-line mass-separated, and $$gamma$$-ray singles and $$gamma$$-$$gamma$$ coincidence measurements were performed. Conversion electrons were also measured and multipolarities of transitions have been derived. A half-life of an excited state was determined by the $$beta$$-$$gamma$$ delayed coincidence technique. The level scheme obtained has been compared with calculations based on the Nilsson model.

Journal Articles

High spin structure of $$^{34}$$S and the proton-neutron coupling of intruder states

Mason, P.*; M$u{a}$rginean, N.*; Lenzi, S. M.*; Ionescu-Bujor, M.*; Della Vedova, F.*; Napoli, D. R.*; Otsuka, Takaharu*; Utsuno, Yutaka; Nowacki, F.*; Axiotis, M.*; et al.

Physical Review C, 71(1), p.014316_1 - 014316_8, 2005/01

 Times Cited Count:23 Percentile:18.53(Physics, Nuclear)

no abstracts in English

Journal Articles

Research activities of Japanese Nuclear Data Committee in the fiscal years of 2001 and 2002

Igashira, Masayuki*; Shibata, Keiichi; Takano, Hideki*; Yamano, Naoki*; Matsunobu, Hiroyuki*; Kitao, Kensuke*; Katakura, Junichi; Nakagawa, Tsuneo; Hasegawa, Akira; Iwasaki, Tomohiko*; et al.

Nippon Genshiryoku Gakkai Wabun Rombunshi, 3(1), p.128 - 139, 2004/03

no abstracts in English

Journal Articles

High spin states in $$^{158}$$Dy

Hayakawa, Takehito; Toh, Yosuke; Oshima, Masumi; Matsuda, Makoto; Hatsukawa, Yuichi; Shizuma, Toshiyuki; Katakura, Junichi; Iimura, Hideki; Mitarai, Shiro*; Zhang, Y.*; et al.

Physical Review C, 68(6), p.067303_1 - 067303_4, 2003/12

 Times Cited Count:2 Percentile:77.94(Physics, Nuclear)

no abstracts in English

Journal Articles

Projectile Coulomb excitation of $$^{78}$$Se

Hayakawa, Takehito; Toh, Yosuke; Oshima, Masumi; Osa, Akihiko; Koizumi, Mitsuo; Hatsukawa, Yuichi; Utsuno, Yutaka; Katakura, Junichi; Matsuda, Makoto; Morikawa, Tsuneyasu*; et al.

Physical Review C, 67(6), p.064310_1 - 064310_6, 2003/06

 Times Cited Count:13 Percentile:37.31(Physics, Nuclear)

no abstracts in English

Journal Articles

Neutron capture cross section to $$^{186}$$Re isomeric state

Hayakawa, Takehito; Shizuma, Toshiyuki; Yamauchi, Toshihiko; Minehara, Eisuke; Arisawa, Takashi

Nuclear Physics A, 718, p.665c - 667c, 2003/05

no abstracts in English

Journal Articles

Electric-dipole transition probabilities between yrast bands in $$^{157}$$Gd

Hayakawa, Takehito; Toh, Yosuke; Oshima, Masumi; Matsuda, Makoto; Hatsukawa, Yuichi; Shinohara, Nobuo; Iimura, Hideki; Shizuma, Toshiyuki; Zhang, Y.*; Sugawara, Masahiko*; et al.

Physics Letters B, 551(1-2), p.79 - 85, 2003/01

 Times Cited Count:8 Percentile:48.03(Astronomy & Astrophysics)

no abstracts in English

Journal Articles

Rotaional alignment of the h$$_{11/2}$$ band in $$^{157}$$Dy

Hayakawa, Takehito; Toh, Yosuke; Oshima, Masumi; Matsuda, Makoto; Hatsukawa, Yuichi; Katakura, Junichi; Iimura, Hideki; Shizuma, Toshiyuki; Mitarai, Shiro*; Sugawara, Masahiko*; et al.

European Physical Journal A, 15(3), p.299 - 302, 2002/11

 Times Cited Count:9 Percentile:50.39(Physics, Nuclear)

no abstracts in English

Journal Articles

Tunneling in high-$$K$$ isomeric decays

Shizuma, Toshiyuki; Shimizu, Yoshifumi*; Hayakawa, Takehito

Journal of Nuclear Science and Technology, 39(11), p.1137 - 1141, 2002/11

 Times Cited Count:3 Percentile:75.07(Nuclear Science & Technology)

We have systematically investigated the highly $$K$$-forbidden transitions observed in the Hf, W and Os region, using the $$gamma$$-tunneling model in which low-$$K$$ and high-$$K$$ states interact through a process of the quantum tunneling. In the present study, we have analyzed $$K$$-forbidden transitions recently observed. The measured hindrance factors are compared with the values calculated using the $$gamma$$-tunneling model. We have also investigated isotope dependences of $$gamma$$ tunneling probabilities particularly for neutron-rich nuclei.

Journal Articles

Nuclear data sheets for A=126

Katakura, Junichi; Kitao, Kensuke*

Nuclear Data Sheets, 97(3-4), p.765 - 926, 2002/11

no abstracts in English

Journal Articles

Soft-rotator model and coupled-channels approach for consistent description of the nuclear collective levels and their excitation by nucleons

Soukhovitskij, E. Sh.*; Chiba, Satoshi

Journal of Nuclear Science and Technology, 39(Suppl.2), p.697 - 702, 2002/08

Coupled-channels optical model approach built on the wave functions of the soft-rotator nuclear Hamiltonian is applied for the self-consistent analyses of the low-lying collective nuclear level structure and nucleon interaction with even-even nuclei in a wide $$A$$- mass region. It succeeds to describe available experimental data and $$B(Elambda )$$ $$gamma$$ - transitions with reasonable accuracy. Along with the account of the global optical potential form and relativistic kinematics, present method was proved to be a powerful tool for studies of nucleon-induced reaction data.

Journal Articles

Polarization transfer in the $$^{16}$$O($$p,p'$$) reaction at forward angles and structure of the spin-dipole resonances

Kawabata, Takahiro*; Ishikawa, Takatsugu*; Ito, M.*; Nakamura, M.*; Sakaguchi, Harutaka*; Takeda, H.*; Taki, T.*; Uchida, Makoto*; Yasuda, Yusuke*; Yosoi, Masaru*; et al.

Physical Review C, 65(6), p.064316_1 - 064316_12, 2002/06

 Times Cited Count:18 Percentile:30.83(Physics, Nuclear)

no abstracts in English

Journal Articles

Multi-quasiparticle states and ${it K}$-forbidden transitions in $$^{183}$$Os

Shizuma, Toshiyuki; Matsuura, Katsuyuki*; Toh, Yosuke; Hayakawa, Takehito; Oshima, Masumi; Hatsukawa, Yuichi; Matsuda, Makoto; Furuno, Kohei*; Sasaki, Yasuyuki*; Komatsubara, Tetsuro*; et al.

Nuclear Physics A, 696(3-4), p.337 - 370, 2001/12

 Times Cited Count:18 Percentile:27.02

High-spin states in $$^{183}$$Os have been studied using the 170Er(18O,5n) reaction at a beam energy of 85 MeV. Nine rotational bands based on 1-, 3-, 5- and 7-quasiparticle excitations have been observed. Nilsson configurations are assigned for the newly observed bands using g-factors deduced from M1/E2 branching ratios within the bands. In addition, two isomers with K=(43/2+) and (43/2-) have been identified. The K=(43/2+) isomer decays directly to the K=9/2+ ground state band with a large difference in the $$K$$ quantum number, $$mitDelta K=$$17. The decay rates are disccused in terms of a tunneling model where high-$$K$$ (isomeric) and low-$$K$$ states interact via fluctuations towards triaxial nuclear shapes.

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