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1. Shape coexistence in 66Se

Author

Z. Elekes, V. Panin, T.R. Rodríguez, K. Sieja, D.S. Ahn, A. Al-Adili, H. Baba, A.I. Stefanescu, K.J. Cook, Cs. Dósa, N. Fukuda, J. Gao, J. Gibelin, K.I. Hahn, Z. Halász, S.W. Huang, T. Isobe, M.M. Juhász, D. Kim, T. Kobayashi, Y. Kondo, Z. Korkulu, A. Kurihara, I. Kuti, H. Miki, K. Miki, T. Motobayashi, H. Otsu, A. Saastamoinen, M. Sasano, H. Sato, T. Shimada, Y. Shimizu, L.G. Sobotka, I. Stefanescu, L. Stuhl, H. Suzuki, H. Takeda, Y. Togano, T. Tomai, L. Trache, D. Tudor, T. Uesaka, Y. Utsuki, H. Wang, A. Yasuda, K. Yoneda, and Y. Yoshitome

Subjects
Neutron knock-out reaction, γ-ray spectroscopy, Nuclear structure, Shape coexistence, Physics, QC1-999
Abstract

The nuclear structure of 66Se, nucleus beyond the N=Z line on the proton-rich side of the valley of stability, was investigated by the neutron knock-out reaction 67Se(12C,X)66Se using a 12C target. The analysis of the singles spectrum of the γ-rays emitted during the de-excitation of the populated low-lying excited states revealed two previously detected (927(4) keV, 1460(32) keV) and three new (744(6) keV, 1210(17) keV, 1661(23) keV) transitions. The 744-keV, the 1210-keV, and the 1460-keV transitions were found to be in coincidence with the one at 927 keV. The spectrum coincident with the 927-keV transition showed a further possible transition at 299(35) keV, which was obscured by significant atomic background in the singles spectrum. This transition might correspond to a peak previously reported at 273(5) keV that could not be assigned to 66Se unambiguously. Based on a comparison of the experimental data to theoretical calculations, four new excited states are proposed which suggest that 66Se exhibits shape coexistence.

Published
2023
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2. Level structures of 56,58Ca cast doubt on a doubly magic 60Ca

Author

S. Chen, F. Browne, P. Doornenbal, J. Lee, A. Obertelli, Y. Tsunoda, T. Otsuka, Y. Chazono, G. Hagen, J.D. Holt, G.R. Jansen, K. Ogata, N. Shimizu, Y. Utsuno, K. Yoshida, N.L. Achouri, H. Baba, D. Calvet, F. Château, N. Chiga, A. Corsi, M.L. Cortés, A. Delbart, J.-M. Gheller, A. Giganon, A. Gillibert, C. Hilaire, T. Isobe, T. Kobayashi, Y. Kubota, V. Lapoux, H.N. Liu, T. Motobayashi, I. Murray, H. Otsu, V. Panin, N. Paul, W. Rodriguez, H. Sakurai, M. Sasano, D. Steppenbeck, L. Stuhl, Y.L. Sun, Y. Togano, T. Uesaka, K. Wimmer, K. Yoneda, O. Aktas, T. Aumann, L.X. Chung, F. Flavigny, S. Franchoo, I. Gasparic, R.-B. Gerst, J. Gibelin, K.I. Hahn, D. Kim, T. Koiwai, Y. Kondo, P. Koseoglou, C. Lehr, B.D. Linh, T. Lokotko, M. MacCormick, K. Moschner, T. Nakamura, S.Y. Park, D. Rossi, E. Sahin, P.-A. Söderström, D. Sohler, S. Takeuchi, H. Törnqvist, V. Vaquero, V. Wagner, S. Wang, V. Werner, X. Xu, H. Yamada, D. Yan, Z. Yang, M. Yasuda, and L. Zanetti

Subjects
Shell evolution, γ Ray spectroscopy, Physics, QC1-999
Abstract

Gamma decays were observed in 56Ca and 58Ca following quasi-free one-proton knockout reactions from 57,59Sc beams at ≈200 MeV/nucleon. For 56Ca, a γ ray transition was measured to be 1456(12) keV, while for 58Ca an indication for a transition was observed at 1115(34) keV. Both transitions were tentatively assigned as the 21+→0gs+ decays, and were compared to results from ab initio and conventional shell-model approaches. A shell-model calculation in a wide model space with a marginally modified effective nucleon-nucleon interaction depicts excellent agreement with experiment for 21+ level energies, two-neutron separation energies, and reaction cross sections, corroborating the formation of a new nuclear shell above the N = 34 shell. Its constituents, the 0f5/2 and 0g9/2 orbitals, are almost degenerate. This degeneracy precludes the possibility for a doubly magic 60Ca and potentially drives the dripline of Ca isotopes to 70Ca or even beyond.

Published
2023
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3. Intruder configurations in 29Ne at the transition into the island of inversion: Detailed structure study of 28Ne

Author

H. Wang, M. Yasuda, Y. Kondo, T. Nakamura, J.A. Tostevin, K. Ogata, T. Otsuka, A. Poves, N. Shimizu, K. Yoshida, N.L. Achouri, H. Al Falou, L. Atar, T. Aumann, H. Baba, K. Boretzky, C. Caesar, D. Calvet, H. Chae, N. Chiga, A. Corsi, H.L. Crawford, F. Delaunay, A. Delbart, Q. Deshayes, Zs. Dombrádi, C. Douma, Z. Elekes, P. Fallon, I. Gašparić, J.-M. Gheller, J. Gibelin, A. Gillibert, M.N. Harakeh, A. Hirayama, C.R. Hoffman, M. Holl, A. Horvat, Á. Horváth, J.W. Hwang, T. Isobe, J. Kahlbow, N. Kalantar-Nayestanaki, S. Kawase, S. Kim, K. Kisamori, T. Kobayashi, D. Körper, S. Koyama, I. Kuti, V. Lapoux, S. Lindberg, F.M. Marqués, S. Masuoka, J. Mayer, K. Miki, T. Murakami, M.A. Najafi, K. Nakano, N. Nakatsuka, T. Nilsson, A. Obertelli, N.A. Orr, H. Otsu, T. Ozaki, V. Panin, S. Paschalis, A. Revel, D. Rossi, A.T. Saito, T. Saito, M. Sasano, H. Sato, Y. Satou, H. Scheit, F. Schindler, P. Schrock, M. Shikata, Y. Shimizu, H. Simon, D. Sohler, O. Sorlin, L. Stuhl, S. Takeuchi, M. Tanaka, M. Thoennessen, H. Törnqvist, Y. Togano, T. Tomai, J. Tscheuschner, J. Tsubota, T. Uesaka, Z. Yang, and K. Yoneda

Subjects
In-beam γ-ray spectroscopy, Island of inversion, Shell evolution, Physics, QC1-999
Abstract

Detailed γ-ray spectroscopy of the exotic neon isotope 28Ne has been performed for the first time using the one-neutron removal reaction from 29Ne on a liquid hydrogen target at 240 MeV/nucleon. Based on an analysis of parallel momentum distributions, a level scheme with spin-parity assignments has been constructed for 28Ne and the negative-parity states are identified for the first time. The measured partial cross sections and momentum distributions reveal a significant intruder p-wave strength providing evidence of the breakdown of the N=20 and N=28 shell gaps. Only a weak, possible f-wave strength was observed to bound final states. Large-scale shell-model calculations with different effective interactions do not reproduce the large p-wave and small f-wave strength observed experimentally, indicating an ongoing challenge for a complete theoretical description of the transition into the island of inversion along the Ne isotopic chain.

Published
2023
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4. Searching for universality of dineutron correlation at the surface of Borromean nuclei

Author

A. Corsi, Y. Kubota, J. Casal, M. Gómez-Ramos, A.M. Moro, G. Authelet, H. Baba, C. Caesar, D. Calvet, A. Delbart, M. Dozono, J. Feng, F. Flavigny, J.-M. Gheller, J. Gibelin, A. Giganon, A. Gillibert, K. Hasegawa, T. Isobe, Y. Kanaya, S. Kawakami, D. Kim, Y. Kiyokawa, M. Kobayashi, N. Kobayashi, T. Kobayashi, Y. Kondo, Z. Korkulu, S. Koyama, V. Lapoux, Y. Maeda, F.M. Marqués, T. Motobayashi, T. Miyazaki, T. Nakamura, N. Nakatsuka, Y. Nishio, A. Obertelli, A. Ohkura, N.A. Orr, S. Ota, H. Otsu, T. Ozaki, V. Panin, S. Paschalis, E.C. Pollacco, S. Reichert, J.-Y. Rousse, A.T. Saito, S. Sakaguchi, M. Sako, C. Santamaria, M. Sasano, H. Sato, M. Shikata, Y. Shimizu, Y. Shindo, L. Stuhl, T. Sumikama, Y.L. Sun, M. Tabata, Y. Togano, J. Tsubota, T. Uesaka, Z.H. Yang, J. Yasuda, K. Yoneda, and J. Zenihiro

Subjects
Quasi-free scattering, Borromean nuclei, Three-body model, Jacobi coordinates, Dineutron, Physics, QC1-999
Abstract

The dineutron correlation is systematically studied in three different Borromean nuclei near the neutron dripline, 11Li, 14Be and 17B, via the (p,pn) knockout reaction measured at the RIBF facility in RIKEN. For the three nuclei, the correlation angle between the valence neutrons is found to be largest in the same range of intrinsic momenta, which can be associated to the nuclear surface. This result reinforces the prediction that the formation of the dineutron is universal in environments with low neutron density, such as the surface of neutron-rich Borromean nuclei.

Published
2023
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5. Unbound states in 17C and p-sd shell-model interactions

Author

S. Kim, J.W. Hwang, Y. Satou, N.A. Orr, T. Nakamura, Y. Kondo, J. Gibelin, N.L. Achouri, T. Aumann, H. Baba, F. Delaunay, P. Doornenbal, N. Fukuda, N. Inabe, T. Isobe, D. Kameda, D. Kanno, N. Kobayashi, T. Kobayashi, T. Kubo, S. Leblond, J. Lee, F.M. Marqués, R. Minakata, T. Motobayashi, D. Murai, T. Murakami, K. Muto, T. Nakashima, N. Nakatsuka, A. Navin, S. Nishi, S. Ogoshi, H. Otsu, H. Sato, Y. Shimizu, H. Suzuki, K. Takahashi, H. Takeda, S. Takeuchi, R. Tanaka, Y. Togano, A.G. Tuff, M. Vandebrouck, and K. Yoneda

Subjects
One-neutron removal reaction, Neutron-rich carbon isotopes, Cross-shell states, Shell-model Hamiltonian, Physics, QC1-999
Abstract

Unbound states in C17 were investigated via one-neutron removal from a C18 beam at an energy of 245 MeV/nucleon on a carbon target. The energy spectrum of C17, above the single-neutron decay threshold, was reconstructed using invariant mass spectroscopy from the measured momenta of the C16 fragment and neutron, and was found to exhibit resonances at Er=0.52(2), 0.77(2), 1.36(1), 1.91(1), 2.22(3) and 3.20(1) MeV. The resonance at Er=0.77(2) MeV [Ex=1.51(3) MeV] was provisionally assigned as the second 5/2+ state. The two resonances at Er=1.91(1) and 3.20(1) MeV [Ex=2.65(2) and 3.94(2) MeV] were identified, through comparison of the energies, cross sections and momentum distributions with shell-model and eikonal reaction calculations, as p-shell hole states with spin-parities 1/21− and 3/21−, respectively. A detailed comparison was made with the results obtained using a range of shell-model interactions. The YSOX shell-model Hamiltonian, the cross-shell part of which is based on the monopole-based universal interaction, was found to provide a very good description of the present results and those for the neighbouring odd-A carbon isotopes – in particular for the negative parity cross-shell states.

Published
2023
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6. A first glimpse at the shell structure beyond 54Ca: Spectroscopy of 55K, 55Ca, and 57Ca

Author

T. Koiwai, K. Wimmer, P. Doornenbal, A. Obertelli, C. Barbieri, T. Duguet, J.D. Holt, T. Miyagi, P. Navrátil, K. Ogata, N. Shimizu, V. Somà, Y. Utsuno, K. Yoshida, N.L. Achouri, H. Baba, F. Browne, D. Calvet, F. Château, S. Chen, N. Chiga, A. Corsi, M.L. Cortés, A. Delbart, J.-M. Gheller, A. Giganon, A. Gillibert, C. Hilaire, T. Isobe, T. Kobayashi, Y. Kubota, V. Lapoux, H.N. Liu, T. Motobayashi, I. Murray, H. Otsu, V. Panin, N. Paul, W. Rodriguez, H. Sakurai, M. Sasano, D. Steppenbeck, L. Stuhl, Y.L. Sun, Y. Togano, T. Uesaka, K. Yoneda, O. Aktas, T. Aumann, L.X. Chung, F. Flavigny, S. Franchoo, I. Gasparic, R.-B. Gerst, J. Gibelin, K.I. Hahn, D. Kim, Y. Kondo, P. Koseoglou, J. Lee, C. Lehr, B.D. Linh, T. Lokotko, M. MacCormick, K. Moschner, T. Nakamura, S.Y. Park, D. Rossi, E. Sahin, P.-A. Söderström, D. Sohler, S. Takeuchi, H. Toernqvist, V. Vaquero, V. Wagner, S. Wang, V. Werner, X. Xu, H. Yamada, D. Yan, Z. Yang, M. Yasuda, and L. Zanetti

Subjects
Radioactive beams, γ-ray spectroscopy, Shell evolution, Physics, QC1-999
Abstract

States in the N=35 and 37 isotopes 55,57Ca have been populated by direct proton-induced nucleon removal reactions from 56,58Sc and 56Ca beams at the RIBF. In addition, the (p,2p) quasi-free single-proton removal reaction from 56Ca was studied. Excited states in 55K, 55Ca, and 57Ca were established for the first time via in-beam γ-ray spectroscopy. Results for the proton and neutron removal reactions from 56Ca to states in 55K and 55Ca for the level energies, excited state lifetimes, and exclusive cross sections agree well with state-of-the-art theoretical calculations using different approaches. The observation of a short-lived state in 57Ca suggests a transition in the calcium isotopic chain from single-particle dominated states at N=35 to collective excitations at N=37.

Published
2022
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7. Rapidity distributions of Z = 1 isotopes and the nuclear symmetry energy from Sn+Sn collisions with radioactive beams at 270 MeV/nucleon

Author

M. Kaneko, T. Murakami, T. Isobe, M. Kurata-Nishimura, A. Ono, N. Ikeno, J. Barney, G. Cerizza, J. Estee, G. Jhang, J.W. Lee, W.G. Lynch, C. Santamaria, C.Y. Tsang, M.B. Tsang, R. Wang, D.S. Ahn, L. Atar, T. Aumann, H. Baba, K. Boretzky, J. Brzychczyk, N. Chiga, N. Fukuda, I. Gašparić, B. Hong, A. Horvat, T. Ichihara, K. Ieki, N. Inabe, Y.J. Kim, T. Kobayashi, Y. Kondo, P. Lasko, H.S. Lee, Y. Leifels, J. Łukasik, J. Manfredi, A.B. McIntosh, P. Morfouace, T. Nakamura, N. Nakatsuka, S. Nishimura, R. Olsen, H. Otsu, P. Pawłowski, K. Pelczar, D. Rossi, H. Sakurai, H. Sato, H. Scheit, R. Shane, Y. Shimizu, H. Simon, T. Sumikama, D. Suzuki, H. Suzuki, H. Takeda, S. Tangwancharoen, Y. Togano, H. Törnqvist, Z. Xiao, S.J. Yennello, J. Yurkon, and Y. Zhang

Subjects
Heavy radioactive isotope collisions, Cluster productions, Nuclear symmetry energy, Antisymmetrized molecular dynamics, Physics, QC1-999
Abstract

The rapidity distributions of hydrogen isotopes emitted from central collisions of neutron-rich 132Sn+124Sn and neutron-deficient 108Sn+112Sn systems at 270 MeV/nucleon were investigated at RIKEN-RIBF. The data are compared with antisymmetrized molecular dynamics (AMD) calculations and the rapidity distributions can be reproduced after adjusting the in-medium nucleon-nucleon cross sections. The double ratios between the two reaction systems taken for the relative yields of deuteron to proton (d/p) and triton to proton (t/p) are further examined in the midrapidity domain, where the adjustments in the AMD calculations do not affect much on them. The d/p and t/p double ratios at midrapidity agree well with the ratio of the system neutron numbers and its squared value, respectively, and the rapidity dependence of these double ratios is consistent with a picture of partial mixing of colliding nuclei. By comparing with the AMD model which shows a strong symmetry energy dependence of the t/p double ratio, the experimental result in the midrapidity domain favors the calculation with a symmetry-energy slope parameter around L=46 MeV rather than L=108 MeV.

Published
2021
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8. First spectroscopic study of 51Ar by the (p,2p) reaction

Author

M.M. Juhász, Z. Elekes, D. Sohler, Y. Utsuno, K. Yoshida, T. Otsuka, K. Ogata, P. Doornenbal, A. Obertelli, H. Baba, F. Browne, D. Calvet, F. Château, S. Chen, N. Chiga, A. Corsi, M.L. Cortés, A. Delbart, J.-M. Gheller, A. Giganon, A. Gillibert, C. Hilaire, T. Isobe, T. Kobayashi, Y. Kubota, V. Lapoux, T. Motobayashi, I. Murray, H. Otsu, V. Panin, N. Paul, W. Rodriguez, H. Sakurai, M. Sasano, D. Steppenbeck, L. Stuhl, Y.L. Sun, Y. Togano, T. Uesaka, K. Wimmer, K. Yoneda, N.L. Achouri, O. Aktas, T. Aumann, L.X. Chung, Zs. Dombrádi, F. Flavigny, S. Franchoo, I. Gašparić, R.-B. Gerst, J. Gibelin, K.I. Hahn, D. Kim, T. Koiwai, Y. Kondo, P. Koseoglou, J. Lee, C. Lehr, B.D. Linh, H.N. Liu, T. Lokotko, M. MacCormick, K. Moschner, T. Nakamura, S.Y. Park, D. Rossi, E. Sahin, P.-A. Söderström, S. Takeuchi, H. Törnqvist, V. Vaquero, V. Wagner, S. Wang, V. Werner, X. Xu, H. Yamada, D. Yan, Z. Yang, M. Yasuda, and L. Zanetti

Subjects
Proton knock-out reaction, γ-ray spectroscopy, Invariant mass method, Nuclear structure, Shell closure, Physics, QC1-999
Abstract

The nuclear structure of 51Ar, an uncharted territory so far, was studied by the (p,2p) reaction using γ-ray spectroscopy for the bound states and the invariant mass method for the unbound states. Two peaks were detected in the γ-ray spectrum and six peaks were observed in the 50Ar+n relative energy spectrum. Comparing the results to our shell-model calculations, two bound and six unbound states were established. Three of the unbound states could only be placed tentatively due to the low number of counts in the relative energy spectrum of events associated with the decay through the first excited state of 50Ar. The low cross sections populating the two bound states of 51Ar could be interpreted as a clear signature for the presence of significant subshell closures at neutron numbers 32 and 34 in argon isotopes. It was also revealed that due to the two valence holes, unbound collective states coexist with individual-particle states in 51Ar.

Published
2021
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9. Three-body breakup of 6He and its halo structure

Author

Y.L. Sun, T. Nakamura, Y. Kondo, Y. Satou, J. Lee, T. Matsumoto, K. Ogata, Y. Kikuchi, N. Aoi, Y. Ichikawa, K. Ieki, M. Ishihara, T. Kobayshi, T. Motobayashi, H. Otsu, H. Sakurai, T. Shimamura, S. Shimoura, T. Shinohara, T. Sugimoto, S. Takeuchi, Y. Togano, and K. Yoneda

Subjects
Coulomb breakup, Nuclear breakup, Electric dipole response, Halo nuclei, 208Pb(6He, α+2n)X, 12C(6He, α+2n)X, Physics, QC1-999
Abstract

The Borromean halo nucleus 6He has been studied by a kinematically complete measurement of Coulomb and nuclear breakup into α + 2n on Pb and C targets at 70 MeV/nucleon. Fully quantum-mechanical four-body breakup calculations reproduce the energy and angular differential cross sections below Erel∼1 MeV for both targets. The model used here reproduces the 6He ground-state properties as well as α-n and n-n scattering data and predicts an average opening angle 〈θnn〉 of 68∘ between the two halo neutrons. However, the model underestimates the breakup cross sections for higher Erel, indicating a possible contribution from the inelastic breakup. Alternatively, we examine the empirically modified calculations that reproduce the energy-differential cross sections for a wide range of scattering angles for both targets. The extracted B(E1) peaks at Erel∼1.4 MeV and amounts to 1.6(2) e2fm2 for Erel ≤ 20 MeV, resulting 〈θnn〉 = 56−10+9 degrees. In either interpretation, the current results show evidence of the dineutron spatial correlation in 6He.

Published
2021
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10. Symmetry energy investigation with pion production from Sn+Sn systems

Author

G. Jhang, J. Estee, J. Barney, G. Cerizza, M. Kaneko, J.W. Lee, W.G. Lynch, T. Isobe, M. Kurata-Nishimura, T. Murakami, C.Y. Tsang, M.B. Tsang, R. Wang, D.S. Ahn, L. Atar, T. Aumann, H. Baba, K. Boretzky, J. Brzychczyk, N. Chiga, N. Fukuda, I. Gasparic, B. Hong, A. Horvat, K. Ieki, N. Inabe, Y.J. Kim, T. Kobayashi, Y. Kondo, P. Lasko, H.S. Lee, Y. Leifels, J. Łukasik, J. Manfredi, A.B. McIntosh, P. Morfouace, T. Nakamura, N. Nakatsuka, S. Nishimura, R. Olsen, H. Otsu, P. Pawłowski, K. Pelczar, D. Rossi, H. Sakurai, C. Santamaria, H. Sato, H. Scheit, R. Shane, Y. Shimizu, H. Simon, A. Snoch, A. Sochocka, Z. Sosin, T. Sumikama, H. Suzuki, D. Suzuki, H. Takeda, S. Tangwancharoen, H. Toernqvist, Y. Togano, Z.G. Xiao, S.J. Yennello, J. Yurkon, Y. Zhang, Maria Colonna, Dan Cozma, Paweł Danielewicz, Hannah Elfner, Natsumi Ikeno, Che Ming Ko, Justin Mohs, Dmytro Oliinychenko, Akira Ono, Jun Su, Yong Jia Wang, Hermann Wolter, Jun Xu, Ying-Xun Zhang, and Zhen Zhang

Subjects
Physics, QC1-999
Abstract

In the past two decades, pions created in the high density regions of heavy ion collisions have been predicted to be sensitive at high densities to the symmetry energy term in the nuclear equation of state, a property that is key to our understanding of neutron stars. In a new experiment designed to study the symmetry energy, the multiplicities of negatively and positively charged pions have been measured with high accuracy for central 132Sn+124Sn, 112Sn+124Sn, and 108Sn+112Sn collisions at E/A=270 MeV with the SπRIT Time Projection Chamber. While individual pion multiplicities are measured to 4% accuracy, those of the charged pion multiplicity ratios are measured to 2% accuracy. We compare these data to predictions from seven major transport models. The calculations reproduce qualitatively the dependence of the multiplicities and their ratios on the total neutron and proton number in the colliding systems. However, the predictions of the transport models from different codes differ too much to allow extraction of reliable constraints on the symmetry energy from the data. This finding may explain previous contradictory conclusions on symmetry energy constraints obtained from pion data in Au+Au system. These new results call for still better understanding of the differences among transport codes, and new observables that are more sensitive to the density dependence of the symmetry energy.

Published
2021
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11. Restoration of the natural E(1/21+) - E(3/21+) energy splitting in odd-K isotopes towards N = 40

Author

Y.L. Sun, A. Obertelli, P. Doornenbal, C. Barbieri, Y. Chazono, T. Duguet, H.N. Liu, P. Navrátil, F. Nowacki, K. Ogata, T. Otsuka, F. Raimondi, V. Somà, Y. Utsuno, K. Yoshida, N. Achouri, H. Baba, F. Browne, D. Calvet, F. Château, S. Chen, N. Chiga, A. Corsi, M.L. Cortés, A. Delbart, J.-M. Gheller, A. Giganon, A. Gillibert, C. Hilaire, T. Isobe, T. Kobayashi, Y. Kubota, V. Lapoux, T. Motobayashi, I. Murray, H. Otsu, V. Panin, N. Paul, W. Rodriguez, H. Sakurai, M. Sasano, D. Steppenbeck, L. Stuhl, Y. Togano, T. Uesaka, K. Wimmer, K. Yoneda, O. Aktas, T. Aumann, L.X. Chung, F. Flavigny, S. Franchoo, I. Gašparić, R.-B. Gerst, J. Gibelin, K.I. Hahn, D. Kim, T. Koiwai, Y. Kondo, P. Koseoglou, J. Lee, C. Lehr, B.D. Linh, T. Lokotko, M. MacCormick, K. Moschner, T. Nakamura, S.Y. Park, D. Rossi, E. Sahin, D. Sohler, P.-A. Söderström, S. Takeuchi, H. Törnqvist, V. Vaquero, V. Wagner, S. Wang, V. Werner, X. Xu, H. Yamada, D. Yan, Z. Yang, M. Yasuda, and L. Zanetti

Subjects
Physics, QC1-999
Abstract

We report on the first γ-ray spectroscopy of 51,53K produced via the 52,54Ca(p,2p) reactions at ∼250 MeV/nucleon. Unambiguous final-state angular-momentum assignments were achieved for beam intensities down to few particles per second by using a new technique based on reaction vertex tracking combined with a thick liquid-hydrogen target. Through γ-ray spectroscopy and exclusive parallel momentum distribution analysis, 3/2+ ground states and 1/2+ first excited states in 51,53K were established quantifying the natural ordering of the 1d3/2 and 2s1/2 proton-hole states that are restored at N = 32 and 34. State-of-the-art ab initio calculations and shell-model calculations with improved phenomenological effective interactions reproduce the present data and predict consistently the increase of the E(1/21+) - E(3/21+) energy differences towards N = 40. Keywords: Spectroscopy, Shell evolution, 51K, 53K

Published
2020
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12. Spectroscopy of 2565,67Mn: Strong coupling in the N = 40 'island of inversion'

Author

X.Y. Liu, Z. Liu, B. Ding, P. Doornenbal, A. Obertelli, S.M. Lenzi, P.M. Walker, L.X. Chung, B.D. Linh, G. Authelet, H. Baba, D. Calvet, F. Château, A. Corsi, A. Delbart, J.-M. Gheller, A. Gillibert, T. Isobe, V. Lapoux, M. Matsushita, S. Momiyama, T. Motobayashi, M. Niikura, F. Nowacki, H. Otsu, C. Péron, A. Peyaud, E.C. Pollacco, J.-Y. Roussé, H. Sakurai, M. Sasano, Y. Shiga, S. Takeuchi, R. Taniuchi, T. Uesaka, H. Wang, K. Yoneda, Y.H. Lam, T.H. Huang, M.D. Sun, W.Q. Zhang, H.Y. Lu, D.S. Hou, F. Browne, Zs. Dombradi, S. Franchoo, F. Giacoppo, A. Gottardo, K. Hadynska-Klek, Z. Korkulu, S. Koyama, Y. Kubota, J. Lee, M. Lettmann, R. Lozeva, K. Matsui, T. Miyazaki, S. Nishimura, C. Louchart, L. Olivier, S. Ota, Z. Patel, E. Sahin, C. Santamaria, C. Shand, P.-A. Söderström, G.L. Stefan, D. Steppenbeck, T. Sumikama, D. Suzuki, Zs. Vajta, V. Werner, J. Wu, Z. Xu, X.H. Zhou, Y.H. Zhang, H.S. Xu, and F.S. Zhang

Subjects
Physics, QC1-999
Abstract

Excited states in 63,65,67Mn were studied via in-beam γ-ray spectroscopy following knockout reactions from 68Fe. Similar level schemes, consisting of the 11/2−, 9/2−, 7/2− and 5/2g.s.− level sequence, connected by I→I−1 transitions, were established, the first time for 65,67Mn. Their level structures show features consistent with strongly-coupled rotational bands with K=5/2. State-of-the-art shell-model calculations with the modified LNPS effective interaction reproduce the observed levels remarkably well and suggest the dominance of 4-particle-4-hole neutron configurations for all the states. The data on the low-lying excited states of odd-mass 53−67Mn provide a textbook example of nuclear structure evolution from weak coupling through decoupling to strong coupling along a single isotopic chain on the n-rich side of the β stability line. These results help to deepen our understanding of the N=40 “island of inversion”. Keywords: In-beam γ-ray spectroscopy, “Island of inversion” around N=40, Strong coupling, Structure evolution

Published
2018
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13. Proton single particle energies next to 78Ni: Spectroscopy of 77Cu via single proton knock-out reaction

Author

Zs. Vajta, D. Sohler, Y. Shiga, K. Yoneda, K. Sieja, D. Steppenbeck, Zs. Dombrádi, N. Aoi, P. Doornenbal, J. Lee, H. Liu, M. Matsushita, S. Takeuchi, H. Wang, H. Baba, P. Bednarczyk, Zs. Fülöp, S. Go, T. Hashimoto, E. Ideguchi, K. Ieki, K. Kobayashi, Y. Kondo, R. Minakata, T. Motobayashi, D. Nishimura, H. Otsu, H. Sakurai, Y. Sun, A. Tamaii, R. Tanaka, Z. Tian, T. Yamamoto, X. Yang, Z. Yang, Y. Ye, R. Yokoyama, and J. Zenihiro

Subjects
Physics, QC1-999
Abstract

Excited states of 77Cu have been investigated by use of single proton knock-out reaction at the Radioactive Isotope Beam Factory in RIKEN in order to reveal the main components of the proton single-particle states. Three excited states were observed at 271, 902 and 2068 keV in 77Cu. The lowest-energy excited state follows the trend predicted for the crossing of the 3/21− and 5/21− states. Comparing the excitation energies of the 3/2−, 5/2− and 7/2− levels from 69Cu to 77Cu one can see that the Z=28 shell gap between the p3/2 and f7/2 states is rather stable, while the f5/2−f7/2 spin–orbit splitting decreases by ∼1.5 MeV in agreement with shell model calculations using the tensor force.

Published
2018
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14. Shell evolution beyond Z=28 and N=50: Spectroscopy of 81,82,83,84Zn

Author

C.M. Shand, Zs. Podolyák, M. Górska, P. Doornenbal, A. Obertelli, F. Nowacki, T. Otsuka, K. Sieja, J.A. Tostevin, Y. Tsunoda, G. Authelet, H. Baba, D. Calvet, A. Château, S. Chen, A. Corsi, A. Delbart, J.M. Gheller, A. Giganon, A. Gillibert, T. Isobe, V. Lapoux, M. Matsushita, S. Momiyama, T. Motobayashi, M. Niikura, H. Otsu, N. Paul, C. Péron, A. Peyaud, E.C. Pollacco, J.-Y. Roussé, H. Sakurai, C. Santamaria, M. Sasano, Y. Shiga, D. Steppenbeck, S. Takeuchi, R. Taniuchi, T. Uesaka, H. Wang, K. Yoneda, T. Ando, T. Arici, A. Blazhev, F. Browne, A.M. Bruce, R.J. Carroll, L.X. Chung, M.L. Cortés, M. Dewald, B. Ding, Zs. Dombrádi, F. Flavigny, S. Franchoo, F. Giacoppo, A. Gottardo, K. Hadyńska-Klęk, A. Jungclaus, Z. Korkulu, S. Koyama, Y. Kubota, J. Lee, M. Lettmann, B.D. Linh, J. Liu, Z. Liu, C. Lizarazo, C. Louchart, R. Lozeva, K. Matsui, T. Miyazaki, K. Moschner, M. Nagamine, N. Nakatsuka, S. Nishimura, C.R. Nita, C.R. Nobs, L. Olivier, S. Ota, R. Orlandi, Z. Patel, P.H. Regan, M. Rudigier, E. Şahin, T. Saito, P.-A. Söderström, I. Stefan, T. Sumikama, D. Suzuki, Zs. Vajta, V. Vaquero, V. Werner, K. Wimmer, J. Wu, and Z.Y. Xu

Subjects
Physics, QC1-999
Abstract

We report on the measurement of new low-lying states in the neutron-rich 81,82,83,84Zn nuclei via in-beam γ-ray spectroscopy. These include the 41+→21+ transition in 82Zn, the 21+→0g.s.+ and 41+→21+ transitions in 84Zn, and low-lying states in 81,83Zn were observed for the first time. The reduced E(21+) energies and increased E(41+)/E(2+1) ratios at N=52, 54 compared to those in 80Zn attest that the magicity is confined to the neutron number N=50 only. The deduced level schemes are compared to three state-of-the-art shell model calculations and a good agreement is observed with all three calculations. The newly observed 2+ and 4+ levels in 84Zn suggest the onset of deformation towards heavier Zn isotopes, which has been incorporated by taking into account the upper sdg orbitals in the Ni78-II and the PFSDG-U models.

Published
2017
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15. Single-neutron knockout from 20C and the structure of 19C

Author

J.W. Hwang, S. Kim, Y. Satou, N.A. Orr, Y. Kondo, T. Nakamura, J. Gibelin, N.L. Achouri, T. Aumann, H. Baba, F. Delaunay, P. Doornenbal, N. Fukuda, N. Inabe, T. Isobe, D. Kameda, D. Kanno, N. Kobayashi, T. Kobayashi, T. Kubo, S. Leblond, J. Lee, F.M. Marqués, R. Minakata, T. Motobayashi, D. Murai, T. Murakami, K. Muto, T. Nakashima, N. Nakatsuka, A. Navin, S. Nishi, S. Ogoshi, H. Otsu, H. Sato, Y. Shimizu, H. Suzuki, K. Takahashi, H. Takeda, S. Takeuchi, R. Tanaka, Y. Togano, A.G. Tuff, M. Vandebrouck, and K. Yoneda

Subjects
Heavy-ion knockout, Invariant mass spectroscopy, Shell evolution, Physics, QC1-999
Abstract

The low-lying unbound level structure of the halo nucleus 19C has been investigated using single-neutron knockout from 20C on a carbon target at 280 MeV/nucleon. The invariant mass spectrum, derived from the momenta of the forward going beam velocity 18C fragment and neutrons, was found to be dominated by a very narrow near threshold (Erel=0.036(1) MeV) peak. Two less strongly populated resonance-like features were also observed at Erel=0.84(4) and 2.31(3) MeV, both of which exhibit characteristics consistent with neutron p-shell hole states. Comparisons of the energies, measured cross sections and parallel momentum distributions to the results of shell-model and eikonal reaction calculations lead to spin-parity assignments of 5/21+ and 1/21− for the levels at Ex=0.62(9) and 2.89(10) MeV with Sn=0.58(9) MeV. Spectroscopic factors were also deduced and found to be in reasonable accord with shell-model calculations. The valence neutron configuration of the 20C ground state is thus seen to include, in addition to the known 1s1/22 component, a significant 0d5/22 contribution. The level scheme of 19C, including significantly the 1/21− cross-shell state, is well accounted for by the YSOX shell-model interaction developed from the monopole-based universal interaction.

Published
2017
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16. Observation of isoscalar and isovector dipole excitations in neutron-rich 20O

Author

N. Nakatsuka, H. Baba, T. Aumann, R. Avigo, S.R. Banerjee, A. Bracco, C. Caesar, F. Camera, S. Ceruti, S. Chen, V. Derya, P. Doornenbal, A. Giaz, A. Horvat, K. Ieki, T. Inakura, N. Imai, T. Kawabata, N. Kobayashi, Y. Kondo, S. Koyama, M. Kurata-Nishimura, S. Masuoka, M. Matsushita, S. Michimasa, B. Million, T. Motobayashi, T. Murakami, T. Nakamura, T. Ohnishi, H.J. Ong, S. Ota, H. Otsu, T. Ozaki, A. Saito, H. Sakurai, H. Scheit, F. Schindler, P. Schrock, Y. Shiga, M. Shikata, S. Shimoura, D. Steppenbeck, T. Sumikama, I. Syndikus, H. Takeda, S. Takeuchi, A. Tamii, R. Taniuchi, Y. Togano, J. Tscheuschner, J. Tsubota, H. Wang, O. Wieland, K. Wimmer, Y. Yamaguchi, K. Yoneda, and J. Zenihiro

Subjects
O20, Low-energy dipole excitation, Inelastic α scattering, Virtual-photon excitation, Physics, QC1-999
Abstract

The isospin characters of low-energy dipole excitations in neutron-rich unstable nucleus 20O were investigated, for the first time in unstable nuclei. Two spectra obtained from a dominant isovector probe (O20+Au) and a dominant isoscalar probe (O20+α) were compared and analyzed by the distorted-wave Born approximation to extract independently the isovector and isoscalar dipole strengths. Two known 1− states with large isovector dipole strengths at energies of 5.36(5) MeV (11−) and 6.84(7) MeV (12−) were also excited by the isoscalar probe. These two states were found to have different isoscalar dipole strengths, 2.70(32)% (11−) and 0.67(12)% (12−), respectively, in exhaustion of the isoscalar dipole-energy-weighted sum rule. The difference in isoscalar strength indicated that they have different underlying structures.

Published
2017
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17. Shell evolution of N = 40 isotones towards 60Ca: First spectroscopy of 62Ti

Author

M.L. Cortés, W. Rodriguez, P. Doornenbal, A. Obertelli, J.D. Holt, S.M. Lenzi, J. Menéndez, F. Nowacki, K. Ogata, A. Poves, T.R. Rodríguez, A. Schwenk, J. Simonis, S.R. Stroberg, K. Yoshida, L. Achouri, H. Baba, F. Browne, D. Calvet, F. Château, S. Chen, N. Chiga, A. Corsi, A. Delbart, J.-M. Gheller, A. Giganon, A. Gillibert, C. Hilaire, T. Isobe, T. Kobayashi, Y. Kubota, V. Lapoux, H.N. Liu, T. Motobayashi, I. Murray, H. Otsu, V. Panin, N. Paul, H. Sakurai, M. Sasano, D. Steppenbeck, L. Stuhl, Y.L. Sun, Y. Togano, T. Uesaka, K. Wimmer, K. Yoneda, O. Aktas, T. Aumann, L.X. Chung, F. Flavigny, S. Franchoo, I. Gašparić, R.-B. Gerst, J. Gibelin, K.I. Hahn, D. Kim, T. Koiwai, Y. Kondo, P. Koseoglou, J. Lee, C. Lehr, B.D. Linh, T. Lokotko, M. MacCormick, K. Moschner, T. Nakamura, S.Y. Park, D. Rossi, E. Sahin, D. Sohler, P.-A. Söderström, S. Takeuchi, H. Toernqvist, V. Vaquero, V. Wagner, S. Wang, V. Werner, X. Xu, H. Yamada, D. Yan, Z. Yang, M. Yasuda, and L. Zanetti

Subjects
Physics, QC1-999
Abstract

Excited states in the N=40 isotone 62Ti were populated via the 63V(p,2p)62Ti reaction at ∼200 MeV/nucleon at the Radioactive Isotope Beam Factory and studied using γ-ray spectroscopy. The energies of the 21+→0gs+ and 41+→21+ transitions, observed here for the first time, indicate a deformed 62Ti ground state. These energies are increased compared to the neighboring 64Cr and 66Fe 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. The shell-model calculations for 62Ti show a dominant configuration with four neutrons excited across the N=40 gap. Likewise, they indicate that the N=40 island of inversion extends down to Z=20, disfavoring a possible doubly magic character of the elusive 60Ca. Keywords: Shell evolution, Radioactive beams, Gamma-ray spectroscopy

Published
2020
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18. Structure of 13Be probed via quasi-free scattering

Author

A. Corsi, Y. Kubota, J. Casal, M. Gómez-Ramos, A.M. Moro, G. Authelet, H. Baba, C. Caesar, D. Calvet, A. Delbart, M. Dozono, J. Feng, F. Flavigny, J.-M. Gheller, J. Gibelin, A. Giganon, A. Gillibert, K. Hasegawa, T. Isobe, Y. Kanaya, S. Kawakami, D. Kim, Y. Kiyokawa, M. Kobayashi, N. Kobayashi, T. Kobayashi, Y. Kondo, Z. Korkulu, S. Koyama, V. Lapoux, Y. Maeda, F.M. Marqués, T. Motobayashi, T. Miyazaki, T. Nakamura, N. Nakatsuka, Y. Nishio, A. Obertelli, A. Ohkura, N.A. Orr, S. Ota, H. Otsu, T. Ozaki, V. Panin, S. Paschalis, E.C. Pollacco, S. Reichert, J.-Y. Rousse, A.T. Saito, S. Sakaguchi, M. Sako, C. Santamaria, M. Sasano, H. Sato, M. Shikata, Y. Shimizu, Y. Shindo, L. Stuhl, T. Sumikama, Y.L. Sun, M. Tabata, Y. Togano, J. Tsubota, T. Uesaka, Z.H. Yang, J. Yasuda, K. Yoneda, and J. Zenihiro

Subjects
Physics, QC1-999
Abstract

We present an investigation of the structure of 13Be obtained via a kinematically complete measurement of the (p,pn) reaction in inverse kinematics at 265 MeV/nucleon. The relative energy spectrum of 13Be is compared to Transfer-to-the-Continuum calculations which use as structure inputs the overlaps of the 14Be ground-state wave function, computed in a three-body model, with the unbound states of the 13Be residual nucleus. The key role of neutron p-wave orbital in the interpretation of the low-relative-energy part of the spectrum is discussed. Keywords: Quasi-free scattering, Borromean nuclei, Three-body model, Resonances

Published
2019
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19. Interaction cross section study of the two-neutron halo nucleus 22C

Author

Y. Togano, T. Nakamura, Y. Kondo, J.A. Tostevin, A.T. Saito, J. Gibelin, N.A. Orr, N.L. Achouri, T. Aumann, H. Baba, F. Delaunay, P. Doornenbal, N. Fukuda, J.W. Hwang, N. Inabe, T. Isobe, D. Kameda, D. Kanno, S. Kim, N. Kobayashi, T. Kobayashi, T. Kubo, S. Leblond, J. Lee, F.M. Marqués, R. Minakata, T. Motobayashi, D. Murai, T. Murakami, K. Muto, T. Nakashima, N. Nakatsuka, A. Navin, S. Nishi, S. Ogoshi, H. Otsu, H. Sato, Y. Satou, Y. Shimizu, H. Suzuki, K. Takahashi, H. Takeda, S. Takeuchi, R. Tanaka, A.G. Tuff, M. Vandebrouck, and K. Yoneda

Subjects
Interaction cross section, Matter radius, Two-neutron halo nucleus 22C, Physics, QC1-999
Abstract

The interaction cross sections (σI) of the very neutron-rich carbon isotopes 19C, 20C and 22C have been measured on a carbon target at 307, 280, and 235 MeV/nucleon, respectively. A σI of 1.280±0.023 b was obtained for 22C, significantly larger than for 19,20C, supporting the halo character of 22C. A 22C root-mean-squared matter radius of 3.44±0.08 fm was deduced using a four-body Glauber reaction model. This value is smaller than an earlier estimate (of 5.4±0.9 fm) derived from a σI measurement on a hydrogen target at 40 MeV/nucleon. These new, higher-precision σI data provide stronger constraints for assessing the consistency of theories describing weakly bound nuclei.

Published
2016
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20. Spallation reaction study for fission products in nuclear waste: Cross section measurements for 137Cs and 90Sr on proton and deuteron

Author

H. Wang, H. Otsu, H. Sakurai, D.S. Ahn, M. Aikawa, P. Doornenbal, N. Fukuda, T. Isobe, S. Kawakami, S. Koyama, T. Kubo, S. Kubono, G. Lorusso, Y. Maeda, A. Makinaga, S. Momiyama, K. Nakano, M. Niikura, Y. Shiga, P.-A. Söderström, H. Suzuki, H. Takeda, S. Takeuchi, R. Taniuchi, Ya. Watanabe, Yu. Watanabe, H. Yamasaki, and K. Yoshida

Subjects
Spallation reaction on proton and deuteron, Transmutation of long-lived fission products, 137Cs, 90Sr, Physics, QC1-999
Abstract

We have studied spallation reactions for the fission products 137Cs and 90Sr for the purpose of nuclear waste transmutation. The spallation cross sections on the proton and deuteron were obtained in inverse kinematics for the first time using secondary beams of 137Cs and 90Sr at 185 MeV/nucleon at the RIKEN Radioactive Isotope Beam Factory. The target dependence has been investigated systematically, and the cross-section differences between the proton and deuteron are found to be larger for lighter spallation products. The experimental data are compared with the PHITS calculation, which includes cascade and evaporation processes. Our results suggest that both proton- and deuteron-induced spallation reactions are promising mechanisms for the transmutation of radioactive fission products.

Published
2016
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21. Multiple Mechanisms in Proton-Induced Nucleon Removal at ∼100 MeV/Nucleon

Author

T. Pohl, Y. L. Sun, A. Obertelli, J. Lee, M. Gómez-Ramos, K. Ogata, K. Yoshida, B. S. Cai, C. X. Yuan, B. A. Brown, H. Baba, D. Beaumel, A. Corsi, J. Gao, J. Gibelin, A. Gillibert, K. I. Hahn, T. Isobe, D. Kim, Y. Kondo, T. Kobayashi, Y. Kubota, P. Li, P. Liang, H. N. Liu, J. Liu, T. Lokotko, F. M. Marqués, Y. Matsuda, T. Motobayashi, T. Nakamura, N. A. Orr, H. Otsu, V. Panin, S. Y. Park, S. Sakaguchi, M. Sasano, H. Sato, H. Sakurai, Y. Shimizu, A. I. Stefanescu, L. Stuhl, D. Suzuki, Y. Togano, D. Tudor, T. Uesaka, H. Wang, X. Xu, Z. H. Yang, K. Yoneda, and J. Zenihiro

Subjects
General Physics and Astronomy
Published
2023
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22. Extended p3/2 Neutron Orbital and the N=32 Shell Closure in Ca52

Author

M. Enciu, H. N. Liu, A. Obertelli, P. Doornenbal, F. Nowacki, K. Ogata, A. Poves, K. Yoshida, N. L. Achouri, H. Baba, F. Browne, D. Calvet, F. Château, S. Chen, N. Chiga, A. Corsi, M. L. Cortés, A. Delbart, J-M. Gheller, A. Giganon, A. Gillibert, C. Hilaire, T. Isobe, T. Kobayashi, Y. Kubota, V. Lapoux, T. Motobayashi, I. Murray, H. Otsu, V. Panin, N. Paul, W. Rodriguez, H. Sakurai, M. Sasano, D. Steppenbeck, L. Stuhl, Y. L. Sun, Y. Togano, T. Uesaka, K. Wimmer, K. Yoneda, O. Aktas, T. Aumann, L. X. Chung, F. Flavigny, S. Franchoo, I. Gasparic, R.-B. Gerst, J. Gibelin, K. I. Hahn, D. Kim, Y. Kondo, P. Koseoglou, J. Lee, C. Lehr, P. J. Li, B. D. Linh, T. Lokotko, M. MacCormick, K. Moschner, T. Nakamura, S. Y. Park, D. Rossi, E. Sahin, P.-A. Söderström, D. Sohler, S. Takeuchi, H. Toernqvist, V. Vaquero, V. Wagner, S. Wang, V. Werner, X. Xu, H. Yamada, D. Yan, Z. Yang, M. Yasuda, and L. Zanetti

Subjects
General Physics and Astronomy
Published
2022
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23. Isoscaling in central Sn+Sn collisions at 270 MeV/u

Author

J. W. Lee, M. B. Tsang, C. Y. Tsang, R. Wang, J. Barney, J. Estee, T. Isobe, M. Kaneko, M. Kurata-Nishimura, W. G. Lynch, T. Murakami, A. Ono, S. R. Souza, D. S. Ahn, L. Atar, T. Aumann, H. Baba, K. Boretzky, J. Brzychczyk, G. Cerizza, N. Chiga, N. Fukuda, I. Gasparic, B. Hong, A. Horvat, K. Ieki, N. Ikeno, N. Inabe, G. Jhang, Y. J. Kim, T. Kobayashi, Y. Kondo, P. Lasko, H. S. Lee, Y. Leifels, J. Łukasik, J. Manfredi, A. B. McIntosh, P. Morfouace, T. Nakamura, N. Nakatsuka, S. Nishimura, H. Otsu, P. Pawłowski, K. Pelczar, D. Rossi, H. Sakurai, C. Santamaria, H. Sato, H. Scheit, R. Shane, Y. Shimizu, H. Simon, A. Snoch, A. Sochocka, T. Sumikama, H. Suzuki, D. Suzuki, H. Takeda, S. Tangwancharoen, Y. Togano, Z. G. Xiao, S. J. Yennello, Y. Zhang, and (the S π RIT collaboration)

Subjects
Nuclear Theory (nucl-th), Nuclear and High Energy Physics, Nuclear Theory, FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment, Heavy radioactive isotope collisions, Cluster productions, Nuclear symmetry energy, Antisymmetrized molecular dynamics
Abstract

Experimental information on fragment emissions is important in understanding the dynamics of nuclear collisions and in the development of transport model simulating heavy-ion collisions. The composition of complex fragments emitted in the heavy-ion collisions can be explained by statistical models, which assume that thermal equilibrium is achieved at collision energies below 100 MeV/u. Our new experimental data together with theoretical analyses for light particles from Sn+Sn collisions at 270 MeV/u, suggest that the hypothesis of thermal equilibrium breaks down for particles emitted with high transfer momentum. To inspect the system's properties in such limit, the scaling features of the yield ratios of particles from two systems, a neutron-rich system of ${}^{132}\mathrm{Sn}+{}^{124}\mathrm{Sn}$ and a nearly symmetric system of ${}^{108}\mathrm{Sn}+{}^{112}\mathrm{Sn}$, are examined in the framework of the statistical multifragmentation model and the antisymmetrized molecular dynamics model. The isoscaling from low energy particles agree with both models. However the observed breakdown of isoscaling for particles with high transverse momentum cannot be explained by the antisymmetrized molecular dynamics model.

Published
2022
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24. Neutron occupancy of the 0d5/2 orbital and the N=16 shell closure in 24O

Author

K. Tshoo, Y. Satou, C.A. Bertulani, H. Bhang, S. Choi, T. Nakamura, Y. Kondo, S. Deguchi, Y. Kawada, Y. Nakayama, K.N. Tanaka, N. Tanaka, Y. Togano, N. Kobayashi, N. Aoi, M. Ishihara, T. Motobayashi, H. Otsu, H. Sakurai, S. Takeuchi, K. Yoneda, F. Delaunay, J. Gibelin, F.M. Marqués, N.A. Orr, T. Honda, T. Kobayashi, T. Sumikama, Y. Miyashita, K. Yoshinaga, M. Matsushita, S. Shimoura, D. Sohler, J.W. Hwang, T. Zheng, Z.H. Li, and Z.X. Cao

Subjects
Physics, QC1-999
Abstract

One-neutron knockout from 24O leading to the first excited state in 23O has been measured for a proton target at a beam energy of 62 MeV/nucleon. The decay energy spectrum of the neutron unbound state of 23O was reconstructed from the measured four momenta of the 22O fragment and emitted neutron. A sharp peak was found at Edecay=50±3 keV, corresponding to an excited state in 23O at 2.78±0.11 MeV, as observed in previous measurements. The longitudinal momentum distribution for this state was consistent with d-wave neutron knockout, providing support for a Jπ assignment of 5/2+. The associated spectroscopic factor was deduced to be C2S(0d5/2)=4.1±0.4 by comparing the measured cross section (σ−1nexp=61±6 mb) with a distorted wave impulse approximation calculation. Such a large occupancy for the neutron 0d5/2 orbital is in line with the N=16 shell closure in 24O.

Published
2014
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25. Discovery of ^{39}Na

Author

D S, Ahn, J, Amano, H, Baba, N, Fukuda, H, Geissel, N, Inabe, S, Ishikawa, N, Iwasa, T, Komatsubara, T, Kubo, K, Kusaka, D J, Morrissey, T, Nakamura, M, Ohtake, H, Otsu, T, Sakakibara, H, Sato, B M, Sherrill, Y, Shimizu, T, Sumikama, H, Suzuki, H, Takeda, O B, Tarasov, H, Ueno, Y, Yanagisawa, and K, Yoshida

Abstract

The new isotope ^{39}Na, the most neutron-rich sodium nucleus observed so far, was discovered at the RIKEN Nishina Center Radioactive Isotope Beam Factory using the projectile fragmentation of an intense ^{48}Ca beam at 345 MeV/nucleon on a beryllium target. Projectile fragments were separated and identified in flight with the large-acceptance two-stage separator BigRIPS. Nine ^{39}Na events have been unambiguously observed in this work and clearly establish the particle stability of ^{39}Na. Furthermore, the lack of observation of ^{35,36}Ne isotopes in this experiment significantly improves the overall confidence that ^{34}Ne is the neutron dripline nucleus of neon. These results provide new key information to understand nuclear binding and nuclear structure under extremely neutron-rich conditions. The newly established stability of ^{39}Na has a significant impact on nuclear models and theories predicting the neutron dripline and also provides a key to understanding the nuclear shell property of ^{39}Na at the neutron number N=28, which is normally a magic number.

Published
2022

26. Observation of a correlated free four-neutron system

Author

M. Duer, T. Aumann, R. Gernhäuser, V. Panin, S. Paschalis, D. M. Rossi, N. L. Achouri, D. Ahn, H. Baba, C. A. Bertulani, M. Böhmer, K. Boretzky, C. Caesar, N. Chiga, A. Corsi, D. Cortina-Gil, C. A. Douma, F. Dufter, Z. Elekes, J. Feng, B. Fernández-Domínguez, U. Forsberg, N. Fukuda, I. Gasparic, Z. Ge, J. M. Gheller, J. Gibelin, A. Gillibert, K. I. Hahn, Z. Halász, M. N. Harakeh, A. Hirayama, M. Holl, N. Inabe, T. Isobe, J. Kahlbow, N. Kalantar-Nayestanaki, D. Kim, S. Kim, T. Kobayashi, Y. Kondo, D. Körper, P. Koseoglou, Y. Kubota, I. Kuti, P. J. Li, C. Lehr, S. Lindberg, Y. Liu, F. M. Marqués, S. Masuoka, M. Matsumoto, J. Mayer, K. Miki, B. Monteagudo, T. Nakamura, T. Nilsson, A. Obertelli, N. A. Orr, H. Otsu, S. Y. Park, M. Parlog, P. M. Potlog, S. Reichert, A. Revel, A. T. Saito, M. Sasano, H. Scheit, F. Schindler, S. Shimoura, H. Simon, L. Stuhl, H. Suzuki, D. Symochko, H. Takeda, J. Tanaka, Y. Togano, T. Tomai, H. T. Törnqvist, J. Tscheuschner, T. Uesaka, V. Wagner, H. Yamada, B. Yang, L. Yang, Z. H. Yang, M. Yasuda, K. Yoneda, L. Zanetti, J. Zenihiro, M. V. Zhukov, Laboratoire de physique corpusculaire de Caen (LPCC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Grand Accélérateur National d'Ions Lourds (GANIL), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Research unit Nuclear & Hadron Physics, and Nuclear Energy

Subjects
Multidisciplinary, Nuclear Force, Nuclear Structure, Tetraneutron, Reactions with Radioactive Beams, Physics, ddc:500, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]
Abstract

Nature 606(7915), 678 - 682 (2022). doi:10.1038/s41586-022-04827-6, Published by Nature Publ. Group, London [u.a.]

Published
2022
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27. Silicon tracker array for RIB experiments at SAMURAI

Author

A. I. Stefanescu, V. Panin, L. Trache, T. Motobayashi, H. Otsu, A. Saastamoinen, T. Uesaka, L. Stuhl, J. Tanaka, D. Tudor, I. C. Stefanescu, A. E. Spiridon, K. Yoneda, H. Baba, M. Kurokawa, Y. Togano, Z. Halasz, M. Sasano, S. Ota, Y. Kubota, D. S. Ahn, T. Kobayashi, Z. Elekes, N. Fukuda, H. Takeda, D. Kim, E. Takada, H. Suzuki, K. Yoshida, Y. Shimizu, H. N. Liu, Y. L. Sun, T. Isobe, J. Gibelin, P. J. Li, J. Zenihiro, F. M. Marqués, M. N. Harakeh, G. G. Kiss, A. Kurihara, M. Yasuda, T. Nakamura, S. Park, Z. Yang, T. Harada, M. Nishimura, H. Sato, I. S. Hahn, K. Y. Chae, J. M. Elson, L. G. Sobotka, C. A. Bertulani, Département de Physique Nucléaire (ex SPhN) (DPHN), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire de physique corpusculaire de Caen (LPCC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), and Normandie Université (NU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Nuclear and High Energy Physics, Physics - Instrumentation and Detectors, FOS: Physical sciences, Instrumentation and Detectors (physics.ins-det), [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Nuclear Experiment (nucl-ex), Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Nuclear Experiment
Abstract

International audience; This work describes a silicon tracker system developed for experiments with proton-rich radioactive ion beams at the SAMURAI superconducting spectrometer of RIBF at RIKEN. The system is designed for accurate angular reconstruction and atomic number identification of relativistic heavy ions and protons which are simultaneously produced in reactions motivated by studies of proton capture reactions of interest for nuclear astrophysics. The technical characteristics of the tracking array are described in detail as are its performance in two pilot experiments. The physics justification for such a system is also presented.

Published
2022
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28. Morphological characterisation of glial and neuronal tau pathology in globular glial tauopathy (Types II and III)

Author

H. Otsu, Shinobu Kawakatsu, Kazuhiro Sanpei, Yasuko Toyoshima, Akiyoshi Kakita, Seishi Terada, Osamu Onodera, Hoyu Takahashi, Koichi Otani, Takeshi Ikeuchi, Hirosato Tanaka, Osamu Yokota, Ryota Kobayashi, Yo Higuchi, Miura Takeshi, and Shigetoshi Kuroda

Subjects
Male, 0301 basic medicine, Pathology, medicine.medical_specialty, Histology, Tau pathology, Cytoplasmic inclusion, Biology, Pathology and Forensic Medicine, 03 medical and health sciences, 0302 clinical medicine, Physiology (medical), medicine, Humans, Aged, Aged, 80 and over, Inclusion Bodies, Neurons, Glial inclusions, Brain, Frontotemporal lobar degeneration, medicine.disease, 030104 developmental biology, Tauopathies, Neurology, Immunohistochemistry, Female, Neurology (clinical), Tauopathy, Astrocytic inclusions, Neuroglia, 030217 neurology & neurosurgery
Abstract

Aims Globular glial tauopathy (GGT) is a new category within the 4-repeat tauopathies that is characterised neuropathologically by tau-positive globular glial inclusions (GGIs), namely, globular oligodendrocytic and astrocytic inclusions (GOIs and GAIs). Occurrence of tau-positive neuronal cytoplasmic inclusions (NCIs) is also a feature. GGT is classified into three pathological subtypes (Types I, II and III). We studied the tau pathology in 6 cases of GGT (Type II, n = 3; Type III, n = 3), with special reference to GAIs and NCIs. Methods Neuropathological examinations were conducted, along with immunohistochemistry, morphometry and three-dimensional imaging, and biochemical and genetic analysis of tau. Results The cortical GAIs in Type II and those in Type III were distinguishable from each other. In the motor cortex, GAIs were much more numerous in Type III than in Type II. Prominent occurrence of perikaryal globular structures was a feature of GAIs in Type III. By contrast, prominent occurrence of radiating process-like structures was a feature of GAIs in Type II. Overall, the GAIs were significantly smaller in Type III than in Type II. NCIs were divisible into three subgroups in terms of shape: diffuse granular, thick cord-like, and round/horseshoe-shaped structures. In all cases, NCIs were a feature of the upper and lower motor neurons. Interestingly, the round/horseshoe-shaped NCIs were observed only in Type III cases. Conclusions These findings, which characterised GAIs and NCIs, indicated that Type II and Type III constitute two distinct pathological subtypes, and also further strengthen the concept of GGT as a distinct entity.

Published
2019
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29. Corrigendum to 'Single-neutron knockout from 20C and the structure of 19C' [Phys. Lett. B 769 (2017) 503–508]

Author

J.W. Hwang, S. Kim, Y. Satou, N.A. Orr, Y. Kondo, T. Nakamura, J. Gibelin, N.L. Achouri, T. Aumann, H. Baba, F. Delaunay, P. Doornenbal, N. Fukuda, N. Inabe, T. Isobe, D. Kameda, D. Kanno, N. Kobayashi, T. Kobayashi, T. Kubo, S. Leblond, J. Lee, F.M. Marqués, R. Minakata, T. Motobayashi, D. Murai, T. Murakami, K. Muto, T. Nakashima, N. Nakatsuka, A. Navin, S. Nishi, S. Ogoshi, H. Otsu, H. Sato, Y. Shimizu, H. Suzuki, K. Takahashi, H. Takeda, S. Takeuchi, R. Tanaka, Y. Togano, A.G. Tuff, M. Vandebrouck, and K. Yoneda

Subjects
Physics, QC1-999
Published
2017
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30. Quasi-free Neutron Knockout Reaction Reveals a Small $s$-orbital Component in the Borromean Nucleus $^{17}$B

Author

Z H, Yang, Y, Kubota, A, Corsi, K, Yoshida, X-X, Sun, J G, Li, M, Kimura, N, Michel, K, Ogata, C X, Yuan, Q, Yuan, G, Authelet, H, Baba, C, Caesar, D, Calvet, A, Delbart, M, Dozono, J, Feng, F, Flavigny, J-M, Gheller, J, Gibelin, A, Giganon, A, Gillibert, K, Hasegawa, T, Isobe, Y, Kanaya, S, Kawakami, D, Kim, Y, Kiyokawa, M, Kobayashi, N, Kobayashi, T, Kobayashi, Y, Kondo, Z, Korkulu, S, Koyama, V, Lapoux, Y, Maeda, F M, Marqués, T, Motobayashi, T, Miyazaki, T, Nakamura, N, Nakatsuka, Y, Nishio, A, Obertelli, A, Ohkura, N A, Orr, S, Ota, H, Otsu, T, Ozaki, V, Panin, S, Paschalis, E C, Pollacco, S, Reichert, J-Y, Roussé, A T, Saito, S, Sakaguchi, M, Sako, C, Santamaria, M, Sasano, H, Sato, M, Shikata, Y, Shimizu, Y, Shindo, L, Stuhl, T, Sumikama, Y L, Sun, M, Tabata, Y, Togano, J, Tsubota, F R, Xu, J, Yasuda, K, Yoneda, J, Zenihiro, S-G, Zhou, W, Zuo, T, Uesaka, Département de Physique Nucléaire (ex SPhN) (DPHN), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Laboratoire de physique corpusculaire de Caen (LPCC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Normandie Université (NU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Nuclear Theory, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment (nucl-ex), Nuclear Experiment, Astrophysics::Galaxy Astrophysics, Nuclear Physics
Abstract

A kinematically complete quasi-free $(p,pn)$ experiment in inverse kinematics was performed to study the structure of the Borromean nucleus $^{17}$B, which had long been considered to have neutron halo. By analyzing the momentum distributions and exclusive cross sections, we obtained the spectroscopic factors for $1s_{1/2}$ and $0d_{5/2}$ orbitals, and a surprisingly small percentage of 9(2)$\%$ was determined for $1s_{1/2}$. Our finding of such a small $1s_{1/2}$ 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 $^{17}$B. The present work gives the smallest $s$- or $p$-orbital component among known nuclei exhibiting halo features, and implies that the dominant occupation of $s$ or $p$ orbitals is not a prerequisite for the occurrence of neutron halo., Accepted for publication in Physical Review Letters,8 pages, 4 figures

Published
2021
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32. Reaction Study on Spallation and Fragmentation of 136Xe Induced by Proton, Deuteron, and Carbon

Author

N. Fukuda, Megumi Niikura, T. Kubo, T. Isobe, G. Lorusso, P. A. Söderström, Yukie Maeda, S. Kawakami, Masayuki Aikawa, Ryo Taniuchi, H. Suzuki, K. Yoshida, S. Kubuno, H. Takeda, Shoko Koyama, H. Wang, Keita Nakano, Yu. Watanabe, D. S. Ahn, X. H. Sun, H. Sakurai, S. Takeuchi, Satoru Momiyama, H. Otsu, Ya. Watanabe, A. Makinaga, Yoshiaki Shiga, and Hayata Yamasaki

Subjects
Nuclear reaction, Nuclear physics, Materials science, Deuterium, Isotope, Proton, Fragmentation (mass spectrometry), chemistry, Isotopes of xenon, chemistry.chemical_element, Spallation, Carbon
Published
2020
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33. Spectroscopy of 2565,67Mn: Strong coupling in the N = 40 'island of inversion'

Author

K. Matsui, H. Otsu, W.Q. Zhang, J.-Y. Roussé, Tadaaki Isobe, R. Lozeva, X.H. Zhou, Satoshi Takeuchi, X.Y. Liu, E. Sahin, Shunpei Koyama, P. Doornenbal, S. Franchoo, Zs. Dombradi, F. Nowacki, Shuichi Ota, C. Santamaria, A. Obertelli, A. Gottardo, Daisuke Suzuki, K. Hadynska-Klek, Jin Wu, L. X. Chung, Masaki Sasano, Ryo Taniuchi, Hiroyoshi Sakurai, Jenny Lee, K. Yoneda, Megumi Niikura, H.S. Xu, P. A. Söderström, C. Louchart, T. Motobayashi, Tomohiro Uesaka, Yuya Kubota, C. Péron, Tsuyoshi Miyazaki, H. Lu, G. Authelet, G. L. Stefan, V. Werner, B. D. Linh, F. Château, A. Delbart, J. M. Gheller, A. Gillibert, C. M. Shand, H. Wang, Z. Liu, S. Nishimura, Zs. Vajta, Philip M Walker, Masafumi Matsushita, Satoru Momiyama, M. Lettmann, F. Browne, S. M. Lenzi, Yoshiaki Shiga, Toshiyuki Sumikama, L. Olivier, E. C. Pollacco, Feng-Shou Zhang, F. Giacoppo, David Steppenbeck, V. Lapoux, T.H. Huang, Zena Patel, H. Baba, M. D. Sun, Y.H. Zhang, D. Calvet, Zhengyu Xu, Alan Peyaud, B. Ding, A. Corsi, Z. Korkulu, Y.H. Lam, and De-fu Hou

Subjects
Physics, Coupling, Nuclear and High Energy Physics, 010308 nuclear & particles physics, Island of inversion, Nuclear structure, Decoupling (cosmology), 01 natural sciences, Molecular physics, Excited state, 0103 physical sciences, Neutron, 010306 general physics, Spectroscopy, Line (formation)
Abstract

Excited states in 63,65,67Mn were studied via in-beam γ-ray spectroscopy following knockout reactions from 68Fe. Similar level schemes, consisting of the 11/2−, 9/2−, 7/2− and 5/2 g.s.− level sequence, connected by I→I−1 transitions, were established, the first time for 65,67Mn. Their level structures show features consistent with strongly-coupled rotational bands with K=5/2 . State-of-the-art shell-model calculations with the modified LNPS effective interaction reproduce the observed levels remarkably well and suggest the dominance of 4-particle-4-hole neutron configurations for all the states. The data on the low-lying excited states of odd-mass 53−67Mn provide a textbook example of nuclear structure evolution from weak coupling through decoupling to strong coupling along a single isotopic chain on the n-rich side of the β stability line. These results help to deepen our understanding of the N=40 “island of inversion”.

Published
2018
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34. Fragmentation of Single-Particle Strength around the Doubly Magic Nucleus ^{132}Sn and the Position of the 0f_{5/2} Proton-Hole State in ^{131}In

Author

V, Vaquero, A, Jungclaus, T, Aumann, J, Tscheuschner, E V, Litvinova, J A, Tostevin, H, Baba, D S, Ahn, R, Avigo, K, Boretzky, A, Bracco, C, Caesar, F, Camera, S, Chen, V, Derya, P, Doornenbal, J, Endres, N, Fukuda, U, Garg, A, Giaz, M N, Harakeh, M, Heil, A, Horvat, K, Ieki, N, Imai, N, Inabe, N, Kalantar-Nayestanaki, N, Kobayashi, Y, Kondo, S, Koyama, T, Kubo, I, Martel, M, Matsushita, B, Million, T, Motobayashi, T, Nakamura, N, Nakatsuka, M, Nishimura, S, Nishimura, S, Ota, H, Otsu, T, Ozaki, M, Petri, R, Reifarth, J L, Rodríguez-Sánchez, D, Rossi, A T, Saito, H, Sakurai, D, Savran, H, Scheit, F, Schindler, P, Schrock, D, Semmler, Y, Shiga, M, Shikata, Y, Shimizu, H, Simon, D, Steppenbeck, H, Suzuki, T, Sumikama, D, Symochko, I, Syndikus, H, Takeda, S, Takeuchi, R, Taniuchi, Y, Togano, J, Tsubota, H, Wang, O, Wieland, K, Yoneda, J, Zenihiro, and A, Zilges

Abstract

Spectroscopic factors of neutron-hole and proton-hole states in ^{131}Sn and ^{131}In, respectively, were measured using one-nucleon removal reactions from doubly magic ^{132}Sn at relativistic energies. For ^{131}In, a 2910(50)-keV γ ray was observed for the first time and tentatively assigned to a decay from a 5/2^{-} state at 3275(50) keV to the known 1/2^{-} level at 365 keV. The spectroscopic factors determined for this new excited state and three other single-hole states provide first evidence for a strong fragmentation of single-hole strength in ^{131}Sn and ^{131}In. The experimental results are compared to theoretical calculations based on the relativistic particle-vibration coupling model and to experimental information for single-hole states in the stable doubly magic nucleus ^{208}Pb.

Published
2019

35. Prominence of Pairing in Inclusive (p,2p) and (p,pn) Cross Sections from Neutron-Rich Nuclei

Author

N, Paul, A, Obertelli, C A, Bertulani, A, Corsi, P, Doornenbal, J L, Rodriguez-Sanchez, G, Authelet, H, Baba, D, Calvet, F, Château, S, Chen, A, Delbart, J-M, Gheller, A, Giganon, A, Gillibert, T, Isobe, V, Lapoux, M, Matsushita, S, Momiyama, T, Motobayashi, M, Niikura, H, Otsu, C, Péron, A, Peyaud, E C, Pollacco, J-Y, Roussé, H, Sakurai, C, Santamaria, M, Sasano, Y, Shiga, D, Steppenbeck, S, Takeuchi, R, Taniuchi, T, Uesaka, H, Wang, K, Yoneda, T, Ando, T, Arici, A, Blazhev, F, Browne, A M, Bruce, R, Carroll, L X, Chung, M L, Cortés, M, Dewald, B, Ding, Zs, Dombradi, F, Flavigny, S, Franchoo, F, Giacoppo, M, Górska, A, Gottardo, K, Hadynska-Klek, Z, Korkulu, S, Koyama, Y, Kubota, A, Jungclaus, J, Lee, M, Lettmann, B D, Linh, J, Liu, Z, Liu, C, Lizarazo, C, Louchart, R, Lozeva, K, Matsui, T, Miyazaki, K, Moschner, S, Nagamine, N, Nakatsuka, C, Nita, S, Nishimura, C R, Nobs, L, Olivier, S, Ota, Z, Patel, Zs, Podolyák, M, Rudigier, E, Sahin, T Y, Saito, C, Shand, P-A, Söderström, I G, Stefan, T, Sumikama, D, Suzuki, R, Orlandi, V, Vaquero, Zs, Vajta, V, Werner, K, Wimmer, J, Wu, and Z, Xu

Subjects
Nuclear Theory, Physics::Accelerator Physics, Nuclear Experiment
Abstract

Fifty-five inclusive single nucleon-removal cross sections from medium mass neutron-rich nuclei impinging on a hydrogen target at ∼ 250 MeV / nucleon are measured at the RIKEN Radioactive Isotope Beam Factory. Systematically higher cross sections are found for proton removal from nuclei with an even number of protons as compared to odd-proton number projectiles for a given neutron separation energy. Neutron removal cross sections display no even-odd splitting, contrary to nuclear cascade model predictions. Both effects are understood through simple considerations of neutron separation energies and bound state level densities originating in pairing correlations in the daughter nuclei. These conclusions are supported by comparison with semimicroscopic model predictions, highlighting the enhanced role of low-lying level densities in nucleon-removal cross sections from loosely bound nuclei.

Published
2019

36. Inverse kinematics (p,n) reactions studies using the WINDS slow neutron detector and the SAMURAI spectrometer

Author

H. Sato, Masaki Sasano, J. Yasuda, K. Kisamori, N. Fukuda, Shuichi Ota, Toshio Kobayashi, Shunpei Koyama, M. Kurata-Nishimura, Noritsugu Nakatsuka, T. Motobayashi, Juzo Zenihiro, M. Kaneko, D. Kameda, Remco Zegers, D. Mücher, Takashi Nakamura, Yosuke Kondo, Masanori Dozono, Naohiro Inabe, W. Chao, Yuya Kubota, J. W. Lee, T. Murakami, A. Krasznahorkay, G. Jhang, Susumu Shimoura, J. Tsubota, H. Suzuki, Tomohiro Uesaka, Motoki Kobayashi, M. Sako, C. S. Lee, Motonobu Takaki, M. Shikata, Hiroshi Tokieda, E. Milman, H. Sakai, Daniel Bazin, Yohei Shimizu, H. Otsu, Hidetada Baba, Tomotsugu Wakasa, Tadaaki Isobe, Yasuhiro Togano, T. Tako, S. Reichert, Kentaro Yako, W. Powell, Shin'ichiro Michimasa, Shoichiro Kawase, S. Tangwancharoen, L. Stuhl, V. Panin, Toshiyuki Sumikama, Hiroyuki Takeda, Yohei Matsuda, K. Yoneda, Toshiyuki Kubo, Satoshi Sakaguchi, and N. Kobayashi

Subjects
Physics, Nuclear and High Energy Physics, Spectrometer, 010308 nuclear & particles physics, 01 natural sciences, Neutron temperature, Nuclear physics, Time of flight, Recoil, 0103 physical sciences, Neutron detection, Neutron, Atomic number, Nuclear Experiment, 010306 general physics, Instrumentation, Excitation
Abstract

We have combined the low-energy neutron detector WINDS (Wide-angle Inverse-kinematics Neutron Detectors for SHARAQ) and the SAMURAI spectrometer at RIKEN Nishina Center RI Beam Factory (RIBF) in order to perform ( p , n ) reactions in inverse kinematics for unstable nuclei in the mass region around A ∼ 100 . In this setup, WINDS is used for detecting recoil neutrons and the SAMURAI spectrometer is used for tagging decay channel of heavy residue. The first experiment by using the setup was performed to study Gamow–Teller transitions from 132 Sn in April 2014. The atomic number Z and mass-to-charge ratio A / Q of the beam residues were determined from the measurements of time of flight, magnetic rigidity and energy loss. The obtained A / Q and Z resolutions were σ A / Q = 0.14 % and σ Z = 0.22 , respectively. Furthermore, owing to the large momentum acceptance ( 50 % ) of SAMURAI, the beam residues associated with the γ , 1n and 2n decay channel were measured in the same magnetic field setting. The kinematic loci of the measured recoil neutron energy and laboratory angle are clearly seen. It shows that the excitation energy up to about 20 MeV can be reconstructed.

Published
2016
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37. SAMURAI in its operation phase for RIBF users

Author

H. W. Wang, Yosuke Kondo, T. Murakami, Toshio Kobayashi, Hiroyoshi Sakurai, T. Motobayashi, Tadaaki Isobe, Nobuyuki Chiga, K. Yoneda, M. B. Tsang, Shunpei Koyama, Yuji Shimizu, H. Otsu, M. Kurata-Nishimura, W. G. Lynch, V. Panin, Meiko Kurokawa, Takashi Nakamura, and Hiromi Sato

Subjects
Physics, Nuclear and High Energy Physics, 010308 nuclear & particles physics, Detector, Phase (waves), 01 natural sciences, Coincidence, Nuclear physics, Momentum, Nuclear magnetic resonance, Cardinal point, Dipole magnet, 0103 physical sciences, Invariant mass, Neutron, 010306 general physics, Instrumentation
Abstract

The Superconducting Analyzer for Multi-particles from Radioisotope beams, SAMURAI, with a large angular and momentum acceptance has entered into the phase of physics experiments. Several experiments have been already run with invariant mass spectroscopy using heavy ions and neutrons, as well as missing mass spectroscopy, by introducing detector arrays around the reaction target upstream of the dipole magnet. Many user devices will be introduced to be coupled with SAMURAI. In the Day-Two phase, an experimental program, SAMURAI08, was performed which took advantage of the large momentum acceptance property of SAMURAI. In this experiment, two or more particles with different Z and A / Z were detected at the focal plane in coincidence. Analysis details are reported as an example for similar experiment in future. A variety of experiments are waiting to be performed, which means that SAMURAI is now open for use by RIBF users.

Published
2016

38. $^{78}$Ni revealed as a doubly magic stronghold against nuclear deformation

Author

Frédéric Nowacki, L. Olivier, K. Yoneda, Tsuyoshi Miyazaki, H. Wang, I. Stefan, J. Simonis, Zhengyu Xu, C. Santamaria, Javier Fernandez Menendez, Ertan Şahin, D. Calvet, Kazuyuki Ogata, R. Lozeva, C. Louchart, Takaharu Otsuka, Satoshi Takeuchi, Alexandre Obertelli, Yusuke Tsunoda, J.-Y. Roussé, Tadaaki Isobe, F. Giacoppo, F. Château, A. Gottardo, E. C. Pollacco, Jenny Lee, T. Sumikama, K. Matsui, Zs. Vajta, David Steppenbeck, Sophie Péru, S. Nishimura, Zena Patel, Frank Browne, C. M. Shand, Tohru Motobayashi, Shinsuke Ota, S. Momiyama, Hiroyoshi Sakurai, K. Hadynska-Klek, H. Otsu, Alfredo Poves, A. Gillibert, Daisuke Suzuki, Hidetada Baba, A. Delbart, S. Franchoo, Yuki Kubota, V. Lapoux, V. Werner, Pär-Anders Söderström, M. Matsushita, Shunpei Koyama, M. Lettmann, Jason D. Holt, Z. Korkulu, A. Corsi, Alan Peyaud, Achim Schwenk, Yoshiaki Shiga, R. Taniuchi, Jin Wu, L. X. Chung, S. R. Stroberg, M. Niikura, Tomohiro Uesaka, Zs. Dombrádi, Pieter Doornenbal, C. Péron, G. Authelet, J. M. Gheller, Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut Pluridisciplinaire Hubert Curien (IPHC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Direction des Applications Militaires (DAM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), and Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Proton, Nuclear Theory, media_common.quotation_subject, Astrophysics::High Energy Astrophysical Phenomena, Strong interaction, FOS: Physical sciences, 01 natural sciences, Asymmetry, Nuclear Theory (nucl-th), Magic number (programming), 0103 physical sciences, Effective field theory, Physics::Atomic and Molecular Clusters, Neutron, Nuclear Experiment (nucl-ex), 010306 general physics, Nuclear Experiment, media_common, Physics, [PHYS]Physics [physics], Multidisciplinary, 010308 nuclear & particles physics, Magic (programming), Atomic nucleus, Atomic physics
Abstract

Nuclear magic numbers, which emerge from the strong nuclear force based on quantum chromodynamics, correspond to fully occupied energy shells of protons, or neutrons inside atomic nuclei. Doubly magic nuclei, with magic numbers for both protons and neutrons, are spherical and extremely rare across the nuclear landscape. While the sequence of magic numbers is well established for stable nuclei, evidence reveals modifications for nuclei with a large proton-to-neutron asymmetry. Here, we provide the first spectroscopic study of the doubly magic nucleus $^{78}$Ni, fourteen neutrons beyond the last stable nickel isotope. We provide direct evidence for its doubly magic nature, which is also predicted by ab initio calculations based on chiral effective field theory interactions and the quasi-particle random-phase approximation. However, our results also provide the first indication of the breakdown of the neutron magic number 50 and proton magic number 28 beyond this stronghold, caused by a competing deformed structure. State-of-the-art phenomenological shell-model calculations reproduce this shape coexistence, predicting further a rapid transition from spherical to deformed ground states with $^{78}$Ni as turning point.

Published
2019
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39. Nuclear Breakup and Coulomb Dissociation of $^{9}$C Nucleus Studied at RIBF RIKEN

Author

Livius Trache, H. Baba, M.N. Harakeh, H. N. Liu, H. Takeda, F. M. Marques, Zoltán Halász, T. Isobe, H. Murakami, H. Otsu, J. Zenihiro, D. H. Kim, M. Sasano, S. Y. Park, Z. Yang, I. C. Stefanescu, D. Tudor, T. Motobayashi, Masahiro Yasuda, A. E. Spiridon, A. N. Petrovici, Y. L. Sun, Takashi Nakamura, Naoki Fukuda, Y. Kubota, K. Yoneda, Masanori Nishimura, Y. Shimizu, T. Uesaka, Yasuhiro Togano, P. J. Li, A. Kurihara, K. Y. Chae, H. Suzuki, D. S. Ahn, A. I. Chilug, T. Kobayashi, J. Gibelin, Shuichi Ota, I. S. Hahn, L. Stuhl, F. Carstoiu, N. T. Zhang, Z. Elekes, Antti Saastamoinen, H. Sato, G. G. Kiss, T. Harada, V. Panin, Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire de physique corpusculaire de Caen (LPCC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), and Normandie Université (NU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Hydrogen, Explosive material, 010308 nuclear & particles physics, chemistry.chemical_element, Inverse, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Breakup, 01 natural sciences, 7. Clean energy, Dissociation (chemistry), Nuclear physics, chemistry, 0103 physical sciences, Radiative transfer, Coulomb, 010306 general physics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Mass gap
Abstract

International audience; The 9C breakup was studied during the SAMURAI29R1 experiment through inclusive and exclusive measurements at energies around 160 AMeV for 9C, in order to evaluate the astrophysical S18 factor for the inverse process 8B(p,γ)9C at energies in the region of astrophysical interest. The radiative proton capture on 8B is important in the hot pp chains, in explosive Hydrogen burning (ppIV and rapI), at temperatures between 0.05 < T9 < 1 K, as possible alternative paths across the A = 8 mass gap. Another goal of this experiment was a detailed study of the breakup reaction mechanism. During the experiment the nuclear breakup process was studied using a natural C target with 425 µm thickness and the Coulomb dissociation by using a natural Pb target with 150 µm thickness. The reaction products were tracked simultaneously using a system of position sensitive Si detectors and in total 1024 output channels were read out by using new dual gain preamplifiers (DGP) specially designed for the experiments of the HI-p collaboration. The SAMURAI29R1 experiment was carried out during the SAMURAI 18Oxygen 2018 Spring campaign and it is part of the HI-p collaboration together with another three experiments. Performances of the setup used and first results of the analysis are presented.

Published
2018
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40. Extraction of the Landau-Migdal Parameter from the Gamow-Teller Giant Resonance in ^{132}Sn

Author

J, Yasuda, M, Sasano, R G T, Zegers, H, Baba, D, Bazin, W, Chao, M, Dozono, N, Fukuda, N, Inabe, T, Isobe, G, Jhang, D, Kameda, M, Kaneko, K, Kisamori, M, Kobayashi, N, Kobayashi, T, Kobayashi, S, Koyama, Y, Kondo, A J, Krasznahorkay, T, Kubo, Y, Kubota, M, Kurata-Nishimura, C S, Lee, J W, Lee, Y, Matsuda, E, Milman, S, Michimasa, T, Motobayashi, D, Muecher, T, Murakami, T, Nakamura, N, Nakatsuka, S, Ota, H, Otsu, V, Panin, W, Powell, S, Reichert, S, Sakaguchi, H, Sakai, M, Sako, H, Sato, Y, Shimizu, M, Shikata, S, Shimoura, L, Stuhl, T, Sumikama, H, Suzuki, S, Tangwancharoen, M, Takaki, H, Takeda, T, Tako, Y, Togano, H, Tokieda, J, Tsubota, T, Uesaka, T, Wakasa, K, Yako, K, Yoneda, and J, Zenihiro

Abstract

The key parameter to discuss the possibility of the pion condensation in nuclear matter, i.e., the so-called Landau-Migdal parameter g^{'}, was extracted by measuring the double-differential cross sections for the (p,n) reaction at 216 MeV/u on a neutron-rich doubly magic unstable nucleus, ^{132}Sn with the quality comparable to data taken with stable nuclei. The extracted strengths for Gamow-Teller (GT) transitions from ^{132}Sn leading to ^{132}Sb exhibit the GT giant resonance (GTR) at the excitation energy of 16.3±0.4(stat)±0.4(syst) MeV with the width of Γ=4.7±0.8 MeV. The integrated GT strength up to E_{x}=25 MeV is S_{GT}^{-}=53±5(stat)_{-10}^{+11}(syst), corresponding to 56% of Ikeda's sum rule of 3(N-Z)=96. The present result accurately constrains the Landau-Migdal parameter as g^{'}=0.68±0.07, thanks to the high sensitivity of the GTR energy to g^{'}. In combination with previous studies on the GTR for ^{90}Zr and ^{208}Pb, the result of this work shows the constancy of this parameter in the nuclear chart region with (N-Z)/A=0.11 to 0.24 and A=90 to 208.

Published
2018

41. Erratum: Persistence of the Z=28 Shell Gap Around ^{78}Ni: First Spectroscopy of ^{79}Cu [Phys. Rev. Lett. 119, 192501 (2017)]

Author

L, Olivier, S, Franchoo, M, Niikura, Z, Vajta, D, Sohler, P, Doornenbal, A, Obertelli, Y, Tsunoda, T, Otsuka, G, Authelet, H, Baba, D, Calvet, F, Château, A, Corsi, A, Delbart, J-M, Gheller, A, Gillibert, T, Isobe, V, Lapoux, M, Matsushita, S, Momiyama, T, Motobayashi, H, Otsu, C, Péron, A, Peyaud, E C, Pollacco, J-Y, Roussé, H, Sakurai, C, Santamaria, M, Sasano, Y, Shiga, S, Takeuchi, R, Taniuchi, T, Uesaka, H, Wang, K, Yoneda, F, Browne, L X, Chung, Z, Dombradi, F, Flavigny, F, Giacoppo, A, Gottardo, K, Hadyńska-Klęk, Z, Korkulu, S, Koyama, Y, Kubota, J, Lee, M, Lettmann, C, Louchart, R, Lozeva, K, Matsui, T, Miyazaki, S, Nishimura, K, Ogata, S, Ota, Z, Patel, E, Sahin, C, Shand, P-A, Söderström, I, Stefan, D, Steppenbeck, T, Sumikama, D, Suzuki, V, Werner, J, Wu, and Z, Xu

Abstract

This corrects the article DOI: 10.1103/PhysRevLett.119.192501.

Published
2018

42. Discovery of ^{60}Ca and Implications For the Stability of ^{70}Ca

Author

O B, Tarasov, D S, Ahn, D, Bazin, N, Fukuda, A, Gade, M, Hausmann, N, Inabe, S, Ishikawa, N, Iwasa, K, Kawata, T, Komatsubara, T, Kubo, K, Kusaka, D J, Morrissey, M, Ohtake, H, Otsu, M, Portillo, T, Sakakibara, H, Sakurai, H, Sato, B M, Sherrill, Y, Shimizu, A, Stolz, T, Sumikama, H, Suzuki, H, Takeda, M, Thoennessen, H, Ueno, Y, Yanagisawa, and K, Yoshida

Abstract

The discovery of the important neutron-rich nucleus _{20}^{60}Ca_{40} and seven others near the limits of nuclear stability is reported from the fragmentation of a 345 MeV/u ^{70}Zn projectile beam on ^{9}Be targets at the radioactive ion-beam factory of the RIKEN Nishina Center. The produced fragments were analyzed and unambiguously identified using the BigRIPS two-stage in-flight separator. The eight new neutron-rich nuclei discovered, ^{47}P, ^{49}S, ^{52}Cl, ^{54}Ar, ^{57}K, ^{59,60}Ca, and ^{62}Sc, are the most neutron-rich isotopes of the respective elements. In addition, one event consistent with ^{59}K was registered. The results are compared with the drip lines predicted by a variety of mass models and it is found that the models in best agreement with the observed limits of existence in the explored region tend to predict the even-mass Ca isotopes to be bound out to at least ^{70}Ca.

Published
2018

43. Inelastic scattering of neutron-rich Ni and Zn isotopes off a proton target

Author

R. Lozeva, M. Lettmann, J.-Y. Roussé, Tadaaki Isobe, Pieter Doornenbal, F. Nowacki, Zena Patel, Satoshi Takeuchi, H. Otsu, K. Matsui, M. L. Cortés, K. Yoneda, C. Santamaria, S. Franchoo, Tohru Motobayashi, Hidetada Baba, E. Sahin, Hiroyoshi Sakurai, Shuichi Ota, C. Péron, S. Nishimura, G. Authelet, F. Giacoppo, Shunpei Koyama, E. C. Pollacco, Alan Peyaud, Jin Wu, L. X. Chung, H. Wang, F. Château, F. Browne, Ryo Taniuchi, J. M. Gheller, Marc Dupuis, T. Sumikama, V. Lapoux, D. Calvet, Zs. Vajta, David Steppenbeck, A. Gillibert, A. Obertelli, Daisuke Suzuki, A. Gottardo, P. A. Söderström, Jenny Lee, S. M. Lenzi, Yoshiaki Shiga, A. Corsi, Kathrin Wimmer, K. Hadynska-Klek, Yuya Kubota, Megumi Niikura, Sophie Péru, Tomohiro Uesaka, I. Stefan, Zs. Dombrádi, C. M. Shand, Norbert Pietralla, A. Delbart, V. Werner, Z. Korkulu, Zhengyu Xu, T. Miyazaki, M. Matsushita, L. Olivier, C. Louchart, Masaki Sasano, Satoru Momiyama, Direction des Applications Militaires (DAM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11)

Subjects
Physics, Nuclear and High Energy Physics, Proton, 010308 nuclear & particles physics, Scattering, Hadron, Nuclear Theory, Inelastic scattering, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, 7. Clean energy, Nuclear physics, 0103 physical sciences, Isotopes of zinc, Gamma spectroscopy, Neutron, 010306 general physics, Nucleon, Nuclear Experiment
Abstract

International audience; Proton inelastic scattering of Ni72,74 and Zn76,80 ions at energies around 235 MeV/nucleon was performed at the Radioactive Isotope Beam Factory and studied using γ-ray spectroscopy. Angular integrated cross sections for direct inelastic scattering to the 21+ and 41+ states were measured. The Jeukenne-Lejeune-Mahaux folding model, extended beyond 200 MeV, was used together with neutron and proton densities stemming from quasiparticle random-phase approximation (QRPA) calculations to interpret the experimental cross sections and to infer neutron to proton matrix element ratios. In addition, coupled-channels calculations with a phenomenological potential were used to determine deformation lengths. For the Ni isotopes, correlations favor neutron excitations, thus conserving the Z=28 gap. A dominance of proton excitation, on the other hand, is observed in the Zn isotopes, pointing to the conservation of the N=50 gap approaching Ni78. These results are in agreement with QRPA and large-scale shell-model calculations.

Published
2018
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44. Spectroscopy of2565,67Mn: Strong coupling in the N = 40 'island of inversion'

Author

X.Y. Liu, Z. Liu, B. Ding, P. Doornenbal, A. Obertelli, S.M. Lenzi, P.M. Walker, L.X. Chung, B.D. Linh, G. Authelet, H. Baba, D. Calvet, F. Château, A. Corsi, A. Delbart, J.-M. Gheller, A. Gillibert, T. Isobe, V. Lapoux, M. Matsushita, S. Momiyama, T. Motobayashi, M. Niikura, F. Nowacki, H. Otsu, C. Péron, A. Peyaud, E.C. Pollacco, J.-Y. Roussé, H. Sakurai, M. Sasano, Y. Shiga, S. Takeuchi, R. Taniuchi, T. Uesaka, H. Wang, K. Yoneda, Y.H. Lam, T.H. Huang, M.D. Sun, W.Q. Zhang, H.Y. Lu, D.S. Hou, F. Browne, Zs. Dombradi, S. Franchoo, F. Giacoppo, A. Gottardo, K. Hadynska-Klek, Z. Korkulu, S. Koyama, Y. Kubota, J. Lee, M. Lettmann, R. Lozeva, K. Matsui, T. Miyazaki, S. Nishimura, C. Louchart, L. Olivier, S. Ota, Z. Patel, E. Sahin, C. Santamaria, C. Shand, P.-A. Söderström, G.L. Stefan, D. Steppenbeck, T. Sumikama, D. Suzuki, Zs. Vajta, V. Werner, J. Wu, Z. Xu, X.H. Zhou, Y.H. Zhang, H.S. Xu, and F.S. Zhang

Subjects
In-beam γ-ray spectroscopy, Strong coupling, Nuclear and High Energy Physics, Structure evolution, “Island of inversion” around N=40, lcsh:Physics, lcsh:QC1-999
Abstract

Excited states in 63,65,67Mn were studied via in-beam γ-ray spectroscopy following knockout reactions from 68Fe. Similar level schemes, consisting of the 11/2−, 9/2−, 7/2− and 5/2g.s.− level sequence, connected by I→I−1 transitions, were established, the first time for 65,67Mn. Their level structures show features consistent with strongly-coupled rotational bands with K=5/2. State-of-the-art shell-model calculations with the modified LNPS effective interaction reproduce the observed levels remarkably well and suggest the dominance of 4-particle-4-hole neutron configurations for all the states. The data on the low-lying excited states of odd-mass 53−67Mn provide a textbook example of nuclear structure evolution from weak coupling through decoupling to strong coupling along a single isotopic chain on the n-rich side of the β stability line. These results help to deepen our understanding of the N=40 “island of inversion”. Keywords: In-beam γ-ray spectroscopy, “Island of inversion” around N=40, Strong coupling, Structure evolution

Published
2018

45. Study of proton- and deuteron-induced spallation reactions on the long-lived fission product 93Zr at 105 MeV/nucleon in inverse kinematics

Author

Satoru Momiyama, Yasushi Watanabe, S. Kawakami, Yosuke Kondo, H. Otsu, Masayuki Aikawa, Teiichiro Matsuzaki, Shoichiro Kawase, T. Ozaki, Meiko Uesaka, Yukie Maeda, Masafumi Matsushita, Hiroyoshi Sakurai, Pieter Doornenbal, Satoshi Takeuchi, Shouhei Araki, Megumi Niikura, Shin'ichiro Michimasa, Sidong Chen, Takashi Nakamura, P. A. Söderström, J. Tsubota, Yoshiaki Shiga, Toshiyuki Sumikama, Hiroshi Suzuki, Shigeru Kubono, D. S. Ahn, Hiroyuki Takeda, Tatsuya Yamamoto, M. Shikata, Kathrin Wimmer, Koichi Yoshida, A. Makinaga, Susumu Shimoura, Tadahiro Kin, Yukinobu Watanabe, Tadaaki Isobe, Takashi Ando, Nobuyuki Chiga, Yasuhiro Togano, Hongwei Wang, Atsumi Saito, Naoki Fukuda, Keita Nakano, Shunpei Koyama, S. Nagamine, Ryo Taniuchi, Takeshi Saito, and Yohei Shimizu

Subjects
Nuclear physics, Physics, Inverse kinematics, Deuterium, Proton, 010308 nuclear & particles physics, 0103 physical sciences, General Physics and Astronomy, Spallation, 010306 general physics, Nucleon, Long-lived fission product, 01 natural sciences
Published
2017
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46. Spallation reaction study for the long-lived fission product 107Pd

Author

Masayuki Aikawa, Tatsuya Yamamoto, Keita Nakano, Takashi Nakamura, Masafumi Matsushita, Hiroshi Suzuki, Atsumi Saito, Susumu Shimoura, Tadahiro Kin, Shunpei Koyama, H. Otsu, Pär-Anders Söderström, S. Nagamine, S. Kawakami, Takeshi Saito, T. Ozaki, Meiko Uesaka, Satoru Momiyama, Tadaaki Isobe, Yoshiaki Shiga, Yosuke Kondo, Toshiyuki Sumikama, Megumi Niikura, Takashi Ando, Shigeru Kubono, Chiga Nobuyuki, Yasuhiro Togano, Shoichiro Kawase, Koichi Yoshida, Yohei Shimizu, Yukinobu Watanabe, Satoshi Takeuchi, Yukie Maeda, Shin'ichiro Michimasa, Pieter Doornenbal, Hongwei Wang, R. Taniuchi, J. Tsubota, Hiroyuki Takeda, Sidong Chen, Hiroyoshi Sakurai, Kathrin Wimmer, Yasushi Watanabe, A. Makinaga, M. Shikata, Shouhei Araki, Teiichiro Matsuzaki, Naoki Fukuda, and DeukSoon Ahn

Subjects
Physics, Nuclear physics, 010308 nuclear & particles physics, 0103 physical sciences, General Physics and Astronomy, Spallation, Fission product yield, 010306 general physics, Long-lived fission product, 01 natural sciences
Published
2017
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47. Nucleus $^{26}$O: A Barely Unbound System beyond the Drip Line

Author

Y, Kondo, T, Nakamura, R, Tanaka, R, Minakata, S, Ogoshi, N A, Orr, N L, Achouri, T, Aumann, H, Baba, F, Delaunay, P, Doornenbal, N, Fukuda, J, Gibelin, J W, Hwang, N, Inabe, T, Isobe, D, Kameda, D, Kanno, S, Kim, N, Kobayashi, T, Kobayashi, T, Kubo, S, Leblond, J, Lee, F M, Marqués, T, Motobayashi, D, Murai, T, Murakami, K, Muto, T, Nakashima, N, Nakatsuka, A, Navin, S, Nishi, H, Otsu, H, Sato, Y, Satou, Y, Shimizu, H, Suzuki, K, Takahashi, H, Takeda, S, Takeuchi, Y, Togano, A G, Tuff, M, Vandebrouck, K, Yoneda, Laboratoire de physique corpusculaire de Caen (LPCC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Grand Accélérateur National d'Ions Lourds (GANIL), Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Normandie Université (NU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Nuclear Theory, Physics::Accelerator Physics, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment
Abstract

International audience; The unbound nucleus 26O has been investigated using invariant-mass spectroscopy following one-proton removal reaction from a 27F beam at 201 MeV/nucleon. The decay products, 24O and two neutrons, were detected in coincidence using the newly commissioned SAMURAI spectrometer at the RIKEN Radioactive Isotope Beam Factory. The 26O ground-state resonance was found to lie only 18±3(stat)±4(syst) keV above threshold. In addition, a higher lying level, which is most likely the first 2+ state, was observed for the first time at 1.28+0.11−0.08 MeV above threshold. Comparison with theoretical predictions suggests that three-nucleon forces, pf-shell intruder configurations, and the continuum are key elements to understanding the structure of the most neutron-rich oxygen isotopes beyond the drip line.

Published
2016
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48. Scintillating fiber detector for momentum tagging light unstable nuclei at intermediate energies

Author

Juzo Zenihiro, Takashi Kobayashi, Hiroyuki Takeda, Yohei Matsuda, H. Otsu, S. Terashima, Y. Iwao, M. Itoh, Harutaka Sakaguchi, and K. Ozeki

Subjects
Physics, Nuclear and High Energy Physics, Scintillating fiber, business.industry, Detector, Separator (oil production), Particle identification, Ion, Momentum, Optics, Cardinal point, Physics::Accelerator Physics, business, Instrumentation, Beam (structure)
Abstract

We have developed a simple one-dimensional scintillating fiber detector (SFD) for momentum tagging high-energy (a few hundred MeV per u) and high-intensity ( ∼ 10 6 particles per second, pps) beams of light ( Z ≤ 10 ) ions in the momentum-dispersive focal plane of a fragment separator. This SFD consists of 60 rows of scintillating fibers that have 2 mm square cross-sections. The detection efficiency is constant for beam intensities between 103 and 106 pps and a position detection efficiency of 100% is achieved by injecting ions obliquely. The position resolution is less than 1 mm (rms). In addition, the SFD is demonstrated to be effective for identifying particles in cocktail beams. These results show that the application of scintillating fibers is found to be one of the most suitable methods to tag the light radioactive ion beams.

Published
2012
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49. Large, thin solid hydrogen target using para-H2

Author

Takashi Kobayashi, K. Tanaka, Yukie Maeda, T. Ohnishi, H. Otsu, S. Y. Suzuki, Harutaka Sakaguchi, K. Ozeki, S. Ishimoto, S. Terashima, K. Kamei, Juzo Zenihiro, Yohei Matsuda, Hiroyuki Takeda, and Akitoshi Koreeda

Subjects
Elastic scattering, Physics, Nuclear and High Energy Physics, Thermal conductivity, Scattering, Solid hydrogen, Sublimation (phase transition), Radiation, Atomic physics, Spin isomers of hydrogen, Instrumentation
Abstract

We have developed a large, thin solid hydrogen target (SHT) that is 30 mm in diameter and 1 mm thick for elastic scattering of protons from unstable nuclei. By using para-H 2 that has a high thermal conductivity at low temperatures, we could prevent sublimation at the target center due to radiation from the higher temperature surroundings. The uniform SHT was used during long-term scattering experiments and it maintained its shape and thickness.

Published
2011
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50. 14Be(p,n)14B reaction at 69 MeV in inverse kinematics

Author

M. Kitayama, Satoshi Takeuchi, Yosuke Kondo, Y. Hashimoto, Y. Yanagisawa, Takashi Sugimoto, H. Otsu, Susumu Shimoura, Yasuhiro Togano, M. Tamaki, Masamichi Ishihara, N. Matsui, Hiroyoshi Sakurai, Tomoko Gomi, Takashi Kobayashi, M. Shinohara, Naoki Fukuda, T. Motobayashi, T. K. Onishi, Yohei Matsuda, Takashi Nakamura, N. Endo, T. Okumura, Y. Satou, Nori Aoi, S. Kawai, T. Nakabayashi, and Hooi Jin Ong

Subjects
Physics, Nuclear and High Energy Physics, Inverse kinematics, Neutron emission, Nuclear Theory, Momentum transfer, Kinematics, Invariant (physics), Nuclear physics, Invariant mass, Atomic physics, Nuclear Experiment, Nucleon, Excitation
Abstract

A Gamow–Teller (GT) transition from the drip-line nucleus 14Be to 14B was studied via the ( p , n ) reaction in inverse kinematics using a secondary 14Be beam at 69 MeV/nucleon. The invariant mass method is employed to reconstruct the energy spectrum. A peak is observed at an excitation energy of 1.27(2) MeV in 14B, together with bumps at 2.08 and 4.06(5) MeV. The observed forward peaking of the state at 1.27 MeV and a good description for the differential cross section, obtained with a DWBA calculation provide support for the 1 + assignment to this state. By extrapolating the cross section to zero momentum transfer the GT-transition strength is deduced. The value is found to compare well with that reported in a β-delayed neutron emission study.

Published
2011
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