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379 results on '"S, Franchoo"'

1. Spectroscopy of deeply bound orbitals in neutron-rich Ca isotopes

Author

P.J. Li, J. Lee, P. Doornenbal, S. Chen, S. Wang, A. Obertelli, Y. Chazono, J.D. Holt, B.S. Hu, K. Ogata, Y. Utsuno, K. Yoshida, N.L. Achouri, H. Baba, F. Browne, 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, K. Boretzky, C. Caesar, L.X. Chung, F. Flavigny, S. Franchoo, I. Gasparic, R.-B. Gerst, J. Gibelin, K.I. Hahn, J. Kahlbow, D. Kim, T. Koiwai, Y. Kondo, D. Körper, P. Koseoglou, C. Lehr, B.D. Linh, T. Lokotko, M. MacCormick, K. Miki, K. Moschner, T. Nakamura, S.Y. Park, D. Rossi, E. Sahin, F. Schindler, H. Simon, P.-A. Söderström, D. Sohler, S. Takeuchi, H. Toernqvist, J. Tscheuschner, V. Vaquero, V. Wagner, V. Werner, X. Xu, H. Yamada, D. Yan, Z. Yang, M. Yasuda, and L. Zanetti

Subjects
Unbound states, Knockout reaction, Single-particle strength, Shell evolution, Physics, QC1-999
Abstract

The calcium isotopes are an ideal system to investigate the evolution of shell structure and magic numbers. Although the properties of surface nucleons in calcium have been well studied, probing the structure of deeply bound nucleons remains a challenge. Here, we report on the first measurement of unbound states in 53Ca and 55Ca, populated from 54,56Ca(p,pn) reactions at a beam energy of around 216 MeV/nucleon at the RIKEN Radioactive Isotopes Beam Factory. The resonance properties, partial cross sections, and momentum distributions of these unbound states were analyzed. Orbital angular momentum l assignments were extracted from momentum distributions based on calculations using the distorted wave impulse approximation (DWIA) reaction model. The resonances at excitation energies of 5516(41)keV in 53Ca and 6000(250)keV in 55Ca indicate a significant l =3 component, providing the first experimental evidence for the ν0f7/2 single-particle strength of unbound hole states in the neutron-rich Ca isotopes. The observed excitation energies and cross-sections point towards extremely localized and well separated strength distributions, with some fragmentation for the ν0f7/2 orbital in 55Ca. These results are in good agreement with predictions from shell-model calculations using the effective GXPF1Bs interaction and ab initio calculations and diverge markedly from the experimental distributions in the nickel isotones at Z=28.

Published
2024
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2. Cross-shell states in 15C: A test for p-sd interactions

Author

J. Lois-Fuentes, B. Fernández-Domínguez, X. Pereira-López, F. Delaunay, W.N. Catford, A. Matta, N.A. Orr, T. Duguet, T. Otsuka, V. Somà, O. Sorlin, T. Suzuki, N.L. Achouri, M. Assié, S. Bailey, B. Bastin, Y. Blumenfeld, R. Borcea, M. Caamaño, L. Caceres, E. Clément, A. Corsi, N. Curtis, Q. Deshayes, F. Farget, M. Fisichella, G. de France, S. Franchoo, M. Freer, J. Gibelin, A. Gillibert, G.F. Grinyer, F. Hammache, O. Kamalou, A. Knapton, Tz. Kokalova, V. Lapoux, B. Le Crom, S. Leblond, F.M. Marqués, P. Morfouace, J. Pancin, L. Perrot, J. Piot, E. Pollacco, D. Ramos, D. Regueira-Castro, C. Rodríguez-Tajes, T. Roger, F. Rotaru, M. Sénoville, N. de Séréville, R. Smith, M. Stanoiu, I. Stefan, C. Stodel, D. Suzuki, J.C. Thomas, N. Timofeyuk, M. Vandebrouck, J. Walshe, and C. Wheldon

Subjects
One neutron pick-up reaction, Neutron-rich carbon isotopes, Phenomenological shell-model, Ab initio calculations, Physics, QC1-999
Abstract

The low-lying structure of 15C has been investigated via the neutron-removal 16C(d,t) reaction. Along with the known bound neutron sd-shell states, unbound p-shell hole states have been observed. The excitation energies and the deduced spectroscopic factors of the cross-shell states are an important measure of the [(p)−1(sd)2] neutron configurations in 15C. Our results show a very good agreement with shell-model calculations using the SFO-tls interaction for 15C. However, this same interaction predicted energies that were too low for the corresponding hole states in the N=9 isotone 17O and adjustment of the p-sd and sd-sd monopole terms was required to match the 17O energies. In addition, the excitation energies and spectroscopic factors have been compared to the first calculations of 15C with the ab initio self-consistent Green's function method employing the NNLOsat interaction. The results show the sensitivity to the size of the N=8 shell gap and highlight the need to go beyond the current truncation scheme.

Published
2023
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3. 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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4. Neutron-proton pairing in the N=Z radioactive fp-shell nuclei 56Ni and 52Fe probed by pair transfer

Author

B. Le Crom, M. Assié, Y. Blumenfeld, J. Guillot, H. Sagawa, T. Suzuki, M. Honma, N.L. Achouri, B. Bastin, R. Borcea, W.N. Catford, E. Clément, L. Cáceres, M. Caamaño, A. Corsi, G. De France, F. Delaunay, N. De Séréville, B. Fernandez-Dominguez, M. Fisichella, S. Franchoo, A. Georgiadou, J. Gibelin, A. Gillibert, F. Hammache, O. Kamalou, A. Knapton, V. Lapoux, S. Leblond, A.O. Macchiavelli, F.M. Marqués, A. Matta, L. Ménager, P. Morfouace, N.A. Orr, J. Pancin, X. Pereira-Lopez, L. Perrot, J. Piot, E. Pollacco, D. Ramos, T. Roger, F. Rotaru, A.M. Sánchez-Benítez, M. Sénoville, O. Sorlin, M. Stanoiu, I. Stefan, C. Stodel, D. Suzuki, J.-C. Thomas, and M. Vandebrouck

Subjects
Radioactive beam, Direct reactions, Neutron-proton pairing, Cooper pairs, Physics, QC1-999
Abstract

The isovector and isoscalar components of neutron-proton pairing are investigated in the N=Z unstable nuclei of the fp-shell through the two-nucleon transfer reaction (p,3He) in inverse kinematics. The combination of particle and gamma-ray detection with radioactive beams of 56Ni and 52Fe, produced by fragmentation at the GANIL/LISE facility, made it possible to carry out this study for the first time in a closed and an open-shell nucleus in the fp-shell. The transfer cross-sections for ground-state to ground-state (J=0+, T=1) and to the first (J=1+, T=0) state were extracted for both cases together with the transfer cross-section ratios σ(0+,T=1)/σ(1+,T=0). They are compared with second-order distorted-wave born approximation (DWBA) calculations. The enhancement of the ground-state to ground-state pair transfer cross-section close to mid-shell, in 52Fe, points towards a superfluid phase in the isovector channel. For the “deuteron-like” transfer, very low cross-sections to the first (J=1+, T=0) state were observed both for 56Ni(p,3He) and 52Fe(p,3He) and are related to a strong hindrance of this channel due to spin-orbit effect. No evidence for an isoscalar deuteron-like condensate is observed.

Published
2022
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5. 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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6. Inclusive cross sections for one- and multi-nucleon removal from Sn, Sb, and Te projectiles beyond the N = 82 shell closure

Author

V. Vaquero, A. Jungclaus, J.L. Rodríguez-Sánchez, J.A. Tostevin, P. Doornenbal, K. Wimmer, S. Chen, E. Nácher, E. Sahin, Y. Shiga, D. Steppenbeck, R. Taniuchi, Z.Y. Xu, T. Ando, H. Baba, F.L. Bello Garrote, S. Franchoo, A. Gargano, K. Hadynska-Klek, A. Kusoglu, J. Liu, T. Lokotko, S. Momiyama, T. Motobayashi, S. Nagamine, N. Nakatsuka, M. Niikura, R. Orlandi, T. Saito, H. Sakurai, P.A. Söderström, G.M. Tveten, Zs. Vajta, and M. Yalcinkaya

Subjects
Physics, QC1-999
Abstract

Inclusive one- and multi-nucleon removal cross sections have been measured for several Sn, Sb and Te isotopes just beyond the N=82 neutron shell closure. The beams were produced in the projectile fission of a 238U beam at the Radioactive Isotope Beam Factory at RIKEN. The experimental cross sections are compared to predictions from the most recent version of the Liege intranuclear cascade model. Although the overall agreement is good, severe discrepancies are observed for the cases of one- and two-neutron removal from 134Sn and 135Sb projectiles and one-proton knockout from all measured N=84 isotones. These discrepancies, as well as the relevance of quasi-elastic reaction channels to the one-neutron removal cross sections, are discussed. In addition, the measured inclusive one-proton knockout cross section for the semi-magic 134Sn projectile is compared to eikonal direct reaction theory calculations to assess if the suppression factors to these calculated cross sections, deduced from data on reactions of lighter projectile nuclei, are also applicable to heavy nuclei. Keywords: Inclusive knockout cross sections, Intranuclear cascade model, Eikonal reaction theory

Published
2019
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7. 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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8. Low-lying single-particle structure of 17C and the N = 14 sub-shell closure

Author

X. Pereira-López, B. Fernández-Domínguez, F. Delaunay, N.L. Achouri, N.A. Orr, W.N. Catford, M. Assié, S. Bailey, B. Bastin, Y. Blumenfeld, R. Borcea, M. Caamaño, L. Caceres, E. Clément, A. Corsi, N. Curtis, Q. Deshayes, F. Farget, M. Fisichella, G. de France, S. Franchoo, M. Freer, J. Gibelin, A. Gillibert, G.F. Grinyer, F. Hammache, O. Kamalou, A. Knapton, T. Kokalova, V. Lapoux, J.A. Lay, B. Le Crom, S. Leblond, J. Lois-Fuentes, F.M. Marqués, A. Matta, P. Morfouace, A.M. Moro, T. Otsuka, J. Pancin, L. Perrot, J. Piot, E. Pollacco, D. Ramos, C. Rodríguez-Tajes, T. Roger, F. Rotaru, M. Sénoville, N. de Séréville, R. Smith, O. Sorlin, M. Stanoiu, I. Stefan, C. Stodel, D. Suzuki, T. Suzuki, J.C. Thomas, N. Timofeyuk, M. Vandebrouck, J. Walshe, and C. Wheldon

Subjects
Physics, QC1-999
Abstract

The first investigation of the single-particle structure of the bound states of 17C, via the d(16C,p) transfer reaction, has been undertaken. The measured angular distributions confirm the spin-parity assignments of 1/2+ and 5/2+ for the excited states located at 217 and 335 keV, respectively. The spectroscopic factors deduced for these states exhibit a marked single-particle character, in agreement with shell model and particle-core model calculations, and combined with their near degeneracy in energy provide clear evidence for the absence of the N=14 sub-shell closure. The very small spectroscopic factor found for the 3/2+ ground state is consistent with theoretical predictions and indicates that the ν1d3/2 strength is carried by unbound states. With a dominant ℓ=0 valence neutron configuration and a very low separation energy, the 1/2+ excited state is a one-neutron halo candidate.

Published
2020
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9. 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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10. 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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11. 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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12. Re-examining the transition into the N=20 island of inversion: Structure of 30Mg

Author

B. Fernández-Domínguez, B. Pietras, W.N. Catford, N.A. Orr, M. Petri, M. Chartier, S. Paschalis, N. Patterson, J.S. Thomas, M. Caamaño, T. Otsuka, A. Poves, N. Tsunoda, N.L. Achouri, J.-C. Angélique, N.I. Ashwood, A. Banu, B. Bastin, R. Borcea, J. Brown, F. Delaunay, S. Franchoo, M. Freer, L. Gaudefroy, S. Heil, M. Labiche, B. Laurent, R.C. Lemmon, A.O. Macchiavelli, F. Negoita, E.S. Paul, C. Rodríguez-Tajes, P. Roussel-Chomaz, M. Staniou, M.J. Taylor, L. Trache, and G.L. Wilson

Subjects
Physics, QC1-999
Abstract

Intermediate energy single-neutron removal from 31Mg has been employed to investigate the transition into the N=20 island of inversion. Levels up to 5 MeV excitation energy in 30Mg were populated and spin-parity assignments were inferred from the corresponding longitudinal momentum distributions and γ-ray decay scheme. Comparison with eikonal-model calculations also permitted spectroscopic factors to be deduced. Surprisingly, the 02+ level in 30Mg was found to have a strength much weaker than expected in the conventional picture of a predominantly 2p−2h intruder configuration having a large overlap with the deformed 31Mg ground state. In addition, negative parity levels were identified for the first time in 30Mg, one of which is located at low excitation energy. The results are discussed in the light of shell-model calculations employing two newly developed approaches with markedly different descriptions of the structure of 30Mg. It is concluded that the cross-shell effects in the region of the island of inversion at Z=12 are considerably more complex than previously thought and that np−nh configurations play a major role in the structure of 30Mg.

Published
2018
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13. Neutron-rich nuclei produced at zero degrees in damped collisions induced by a beam of 18O on a 238U target

Author

I. Stefan, B. Fornal, S. Leoni, F. Azaiez, C. Portail, J.C. Thomas, A.V. Karpov, D. Ackermann, P. Bednarczyk, Y. Blumenfeld, S. Calinescu, A. Chbihi, M. Ciemala, N. Cieplicka-Oryńczak, F.C.L. Crespi, S. Franchoo, F. Hammache, Ł.W. Iskra, B. Jacquot, R.V.F. Janssens, O. Kamalou, T. Lauritsen, M. Lewitowicz, L. Olivier, S.M. Lukyanov, M. Maccormick, A. Maj, P. Marini, I. Matea, M.A. Naumenko, F. de Oliveira Santos, C. Petrone, Yu.E. Penionzhkevich, F. Rotaru, H. Savajols, O. Sorlin, M. Stanoiu, B. Szpak, O.B. Tarasov, and D. Verney

Subjects
Physics, QC1-999
Abstract

Cross sections and corresponding momentum distributions have been measured for the first time at zero degrees for the exotic nuclei obtained from a beam of 18O at 8.5 MeV/A impinging on a 1 mg/cm2 238U target. Sizable cross sections were found for the production of exotic species arising from the neutron transfer and proton removal from the projectile. Comparisons of experimental results with calculations based on deep-inelastic reaction models, taking into account the particle evaporation process, indicate that zero degree is a scattering angle at which the differential reaction cross section for production of exotic nuclei is at its maximum. This result is important in view of the new generation of zero degrees spectrometers under construction, such as the S3 separator at GANIL, for example. Keywords: Nuclear reactions, Deep-inelastic collisions, Exotic nuclei

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. Unexpected high-energy γ emission from decaying exotic nuclei

Author

A. Gottardo, D. Verney, I. Deloncle, S. Péru, C. Delafosse, S. Roccia, I. Matea, C. Sotty, C. Andreoiu, C. Costache, M.-C. Delattre, A. Etilé, S. Franchoo, C. Gaulard, J. Guillot, F. Ibrahim, M. Lebois, M. MacCormick, N. Marginean, R. Marginean, M. Martini, C. Mihai, I. Mitu, L. Olivier, C. Portail, L. Qi, B. Roussière, L. Stan, D. Testov, J. Wilson, and D.T. Yordanov

Subjects
Physics, QC1-999
Abstract

The N=52 Ga83 β decay was studied at ALTO. The radioactive 83Ga beam was produced through the ISOL photofission technique and collected on a movable tape for the measurement of γ-ray emission following β decay. While β-delayed neutron emission has been measured to be 56–85% of the decay path, in this experiment an unexpected high-energy 5–9 MeV γ-ray yield of 16(4)% was observed, coming from states several MeVs above the neutron separation threshold. This result is compared with cutting-edge QRPA calculations, which show that when neutrons deeply bound in the core of the nucleus decay into protons via a Gamow–Teller transition, they give rise to a dipolar oscillation of nuclear matter in the nucleus. This leads to large electromagnetic transition probabilities which can compete with neutron emission, thus affecting the β-decay path. This process is enhanced by an excess of neutrons on the nuclear surface and may thus be a common feature for very neutron-rich isotopes, challenging the present understanding of decay properties of exotic nuclei.

Published
2017
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16. Towards high-resolution laser ionization spectroscopy of the heaviest elements in supersonic gas jet expansion

Author

R. Ferrer, A. Barzakh, B. Bastin, R. Beerwerth, M. Block, P. Creemers, H. Grawe, R. de Groote, P. Delahaye, X. Fléchard, S. Franchoo, S. Fritzsche, L. P. Gaffney, L. Ghys, W. Gins, C. Granados, R. Heinke, L. Hijazi, M. Huyse, T. Kron, Yu. Kudryavtsev, M. Laatiaoui, N. Lecesne, M. Loiselet, F. Lutton, I. D. Moore, Y. Martínez, E. Mogilevskiy, P. Naubereit, J. Piot, S. Raeder, S. Rothe, H. Savajols, S. Sels, V. Sonnenschein, J-C Thomas, E. Traykov, C. Van Beveren, P. Van den Bergh, P. Van Duppen, K. Wendt, and A. Zadvornaya

Subjects
Science
Abstract

It is challenging to explore properties of heavy elements as they can only be produced artificially. Here, the authors demonstrate a high resolution spectroscopy method, studying the properties of actinium, which can be extended to the study of other elements located at the end of the periodic table.

Published
2017
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17. Evidence of octupole-phonons at high spin in 207Pb

Author

D. Ralet, E. Clément, G. Georgiev, A.E. Stuchbery, M. Rejmund, P. Van Isacker, G. de France, A. Lemasson, J. Ljungvall, C. Michelagnoli, A. Navin, D.L. Balabanski, L. Atanasova, A. Blazhev, G. Bocchi, R. Carroll, J. Dudouet, E. Dupont, B. Fornal, S. Franchoo, C. Fransen, C. Müller-Gatermann, A. Goasduff, A. Gadea, P.R. John, D. Kocheva, T. Konstantinopoulos, A. Korichi, A. Kusoglu, S.M. Lenzi, S. Leoni, R. Lozeva, A. Maj, R. Perez, N. Pietralla, C. Shand, O. Stezowski, D. Wilmsen, D. Yordanov, D. Barrientos, P. Bednarczyk, B. Birkenbach, A.J. Boston, H.C. Boston, I. Burrows, B. Cederwall, M. Ciemala, J. Collado, F. Crespi, D. Cullen, H.J. Eberth, J. Goupil, L. Harkness, H. Hess, A. Jungclaus, W. Korten, M. Labiche, R. Menegazzo, D. Mengoni, B. Million, J. Nyberg, Zs. Podolyák, A. Pullia, B. Quintana Arnés, F. Recchia, P. Reiter, F. Saillant, M.D. Salsac, E. Sanchis, C. Theisen, J.J. Valiente Dobon, and O. Wieland

Subjects
Physics, QC1-999
Abstract

A lifetime measurement of the 19/2− state in 207Pb has been performed using the Recoil Distance Doppler-Shift (RDDS) method. The nuclei of interest were produced in multi-nucleon transfer reactions induced by a 208Pb beam impinging on a 100Mo enriched target. The beam-like nuclei were detected and identified in terms of their atomic mass number in the VAMOS++ spectrometer while the prompt γ rays were detected by the AGATA tracking array. The measured large reduced transition probability B(E3,19/2−→13/2+)=40(8) W.u. is the first indication of the octupole phonon at high spin in 207Pb. An analysis in terms of a particle-octupole-vibration coupling model indicates that the measured B(E3) value in 207Pb is compatible with the contributions from single-phonon and single particle E3 as well as E3 strength arising from the double-octupole-phonon 6+ state, all adding coherently. A crucial aspect of the coupling model, namely the strong mixing between single-hole and the phonon-hole states, is confirmed in a realistic shell-model calculation. Keywords: AGATA spectrometer, γ-Ray tracking, VAMOS++ spectrometer, Plunger device, Nuclear deformation, Octupole phonon

Published
2019
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18. First spectroscopic study of odd-odd Cu78

Author

L. G. Pedersen, E. Sahin, A. Görgen, F. L. Bello Garrote, Y. Tsunoda, T. Otsuka, M. Niikura, S. Nishimura, Z. Xu, H. Baba, G. Benzoni, F. Browne, A. M. Bruce, S. Ceruti, F. C. L. Crespi, R. Daido, G. de Angelis, M.-C. Delattre, Zs. Dombradi, P. Doornenbal, Y. Fang, S. Franchoo, G. Gey, A. Gottardo, T. Isobe, P. R. John, H. S. Jung, I. Kojouharov, T. Kubo, N. Kurz, I. Kuti, Z. Li, G. Lorusso, I. Matea, K. Matsui, D. Mengoni, T. Miyazaki, V. Modamio, S. Momiyama, A. I. Morales, P. Morfouace, D. R. Napoli, F. Naqvi, H. Nishibata, A. Odahara, R. Orlandi, Z. Patel, S. Rice, H. Sakurai, H. Schaffner, L. Sinclair, P.-A. Söderström, D. Sohler, I. G. Stefan, T. Sumikama, D. Suzuki, R. Taniuchi, J. Taprogge, Z. Vajta, J. J. Valiente-Dobón, H. Watanabe, V. Werner, J. Wu, A. Yagi, M. Yalcinkaya, R. Yokoyama, and K. Yoshinaga

Published
2023

19. Evolution of single-particle strength in neutron-rich 71Cu

Author

P. Morfouace, S. Franchoo, K. Sieja, I. Matea, L. Nalpas, M. Niikura, A.M. Sánchez-Benítez, I. Stefan, M. Assié, F. Azaiez, D. Beaumel, S. Boissinot, C. Borcea, R. Borcea, G. Burgunder, L. Cáceres, N. De Séréville, Zs. Dombrádi, J. Elseviers, B. Fernández-Domínguez, A. Gillibert, S. Giron, S. Grévy, F. Hammache, O. Kamalou, V. Lapoux, L. Lefebvre, A. Lepailleur, C. Louchart, G. Marquinez-Duran, I. Martel, A. Matta, D. Mengoni, D.R. Napoli, F. Recchia, J.-A. Scarpaci, D. Sohler, O. Sorlin, M. Stanoiu, C. Stodel, J.-C. Thomas, and Zs. Vajta

Subjects
Physics, QC1-999
Abstract

The strength functions of the πf5/2, πp3/2 and πf7/2 orbitals in neutron-rich 71Cu were obtained in a 72Zn(d,3He)71Cu proton pick-up reaction in inverse kinematics using a radioactive beam of 72Zn at 38 MeV/u. A dedicated set-up was developed to overcome the experimental challenges posed by the low cross section of the reaction and the low energy of the outgoing 3He particles. The excitation-energy spectrum was reconstructed and spectroscopic factors were obtained after analysis of the angular distributions with the finite-range Distorted-Wave Born Approximation (DWBA). The results show that unlike for the πf5/2 orbital and contrary to earlier interpretation, the πf7/2 single-particle strength distribution is not appreciably affected by the addition of neutrons beyond N=40.

Published
2015
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20. 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

21. Structure of Ca36 under the Coulomb Magnifying Glass

Author

L. Lalanne, O. Sorlin, A. Poves, M. Assié, F. Hammache, S. Koyama, D. Suzuki, F. Flavigny, V. Girard-Alcindor, A. Lemasson, A. Matta, T. Roger, D. Beaumel, Y. Blumenfeld, B. A. Brown, F. De Oliveira Santos, F. Delaunay, N. de Séréville, S. Franchoo, J. Gibelin, J. Guillot, O. Kamalou, N. Kitamura, V. Lapoux, B. Mauss, P. Morfouace, M. Niikura, J. Pancin, T. Y. Saito, C. Stodel, and J-C. Thomas

Subjects
General Physics and Astronomy
Published
2022

22. Charge radii of exotic potassium isotopes challenge nuclear theory and the magic character of N = 32

Author

Gustav R. Jansen, C. M. Ricketts, Paul-Gerhard Reinhard, S. J. Novario, Shane Wilkins, Fredrik Gustafsson, Á. Koszorús, C. L. Binnersley, Mark Bissell, Witold Nazarewicz, Markus Kortelainen, A. R. Vernon, W. G. Jiang, B. S. Cooper, Gerda Neyens, S. W. Bai, Gaute Hagen, Andreas Ekström, A. Kanellakopoulos, Christian Forssén, R. P. de Groote, B. K. Sahoo, Thomas Papenbrock, Kieran Flanagan, Thomas Elias Cocolios, J. Billowes, R. F. Garcia Ruiz, Xiaofei Yang, S. Franchoo, 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), and Helsinki Institute of Physics

Subjects
kalium, Nuclear Theory, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], nucl-th, Atomic Physics (physics.atom-ph), Other Fields of Physics, FOS: Physical sciences, General Physics and Astronomy, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], nucl-ex, 114 Physical sciences, physics.atom-ph, 01 natural sciences, Effective nuclear charge, Physics - Atomic Physics, Nuclear Theory (nucl-th), Nuclear physics, Charge radius, 0103 physical sciences, Nuclear Physics - Experiment, Neutron, Nuclear Experiment (nucl-ex), Nuclear Experiment, 010306 general physics, Physics, isotoopit, 010308 nuclear & particles physics, Charge (physics), Nuclear matter, [PHYS.PHYS.PHYS-GEN-PH]Physics [physics]/Physics [physics]/General Physics [physics.gen-ph], Coupled cluster, Isotopes of potassium, Nuclear Physics - Theory, ydinfysiikka, Nuclear density
Abstract

Nuclear charge radii are sensitive probes of different aspects of the nucleon-nucleon interaction and the bulk properties of nuclear matter; thus, they provide a stringent test and challenge for nuclear theory. The calcium region has been of particular interest, as experimental evidence has suggested a new magic number at $N = 32$ [1-3], while the unexpectedly large increases in the charge radii [4,5] open new questions about the evolution of nuclear size in neutron-rich systems. By combining the collinear resonance ionization spectroscopy method with $\beta$-decay detection, we were able to extend the charge radii measurement of potassium ($Z =19$) isotopes up to the exotic $^{52}$K ($t_{1/2}$ = 110 ms), produced in minute quantities. Our work provides the first charge radii measurement beyond $N = 32$ in the region, revealing no signature of the magic character at this neutron number. The results are interpreted with two state-of-the-art nuclear theories. For the first time, a long sequence of isotopes could be calculated with coupled-cluster calculations based on newly developed nuclear interactions. The strong increase in the charge radii beyond $N = 28$ is not well captured by these calculations, but is well reproduced by Fayans nuclear density functional theory, which, however, overestimates the odd-even staggering effect. These findings highlight our limited understanding on the nuclear size of neutron-rich systems, and expose pressing problems that are present in some of the best current models of nuclear theory., Comment: submitted version; revision accepted in Nature Physics

Published
2021

23. New narrow resonances observed in the unbound nucleus F15

Author

V. Girard-Alcindor, A. Mercenne, I. Stefan, F. de Oliveira Santos, N. Michel, M. Płoszajczak, M. Assié, A. Lemasson, E. Clément, F. Flavigny, A. Matta, D. Ramos, M. Rejmund, J. Dudouet, D. Ackermann, P. Adsley, M. Assunção, B. Bastin, D. Beaumel, G. Benzoni, R. Borcea, A. J. Boston, D. Brugnara, L. Cáceres, B. Cederwall, I. Celikovic, V. Chudoba, M. Ciemala, J. Collado, F. C. L. Crespi, G. D'Agata, G. De France, F. Delaunay, C. Diget, C. Domingo-Pardo, J. Eberth, C. Fougères, S. Franchoo, F. Galtarossa, A. Georgiadou, J. Gibelin, S. Giraud, V. González, N. Goyal, A. Gottardo, J. Goupil, S. Grévy, V. Guimaraes, F. Hammache, L. J. Harkness-Brennan, H. Hess, N. Jovančević, D. S. Judson Oliver, O. Kamalou, A. Kamenyero, J. Kiener, W. Korten, S. Koyama, M. Labiche, L. Lalanne, V. Lapoux, S. Leblond, A. Lefevre, C. Lenain, S. Leoni, H. Li, A. Lopez-Martens, A. Maj, I. Matea, R. Menegazzo, D. Mengoni, A. Meyer, B. Million, B. Monteagudo, P. Morfouace, J. Mrazek, M. Niikura, J. Piot, Zs. Podolyak, C. Portail, A. Pullia, B. Quintana, F. Recchia, P. Reiter, K. Rezynkina, T. Roger, J. S. Rojo, F. Rotaru, M. D. Salsac, A. M. Sánchez Benítez, E. Sanchis, M. Şenyigit, N. de Séréville, M. Siciliano, J. Simpson, D. Sohler, O. Sorlin, M. Stanoiu, C. Stodel, D. Suzuki, C. Theisen, D. Thisse, J. C.Thomas, P. Ujic, J. J. Valiente-Dobón, and M. Zielińska

Published
2022

24. Study of spin-isospin responses of radioactive nuclei with the background-reduced neutron spectrometer, PANDORA

Author

N. Fukuda, Takashi Nakamura, H. Sakai, Yohei Shimizu, J. Gibelin, Makoto Yasuda, Tomotsugu Wakasa, M. Nishimura, J. Gao, Masashige Matsumoto, S. Franchoo, H. Miki, H. Kasahara, T. Harada, Masaki Sasano, D. Tudor, Toshio Kobayashi, T. Isobe, G. G. Kiss, Tomohiro Uesaka, Yasuhiro Togano, Susumu Shimoura, Atsumi Saito, N. Zhang, I. C. Stefanescu, E. Takada, Zoltán Halász, L. Trache, Yuya Kubota, D. Kim, T. Shimada, Shoko Koyama, Y. Fujino, Juzo Zenihiro, Z. Korkulu, D. Inomoto, Zaihong Yang, H. Sato, H. N. Liu, A. Spiridon, M. Miwa, H. Suzuki, L. Stuhl, V. Panin, H. Baba, Yosuke Kondo, S. Park, K. Yoneda, T. Motobayashi, Y. L. Sun, T. Tomai, I. S. Hahn, Kentaro Yako, X. Sun, A. Kurihara, M.N. Harakeh, Y. Hirai, D. S. Ahn, A. I. Chilug, Hideaki Otsu, Hiroki Yamada, Shin'ichiro Michimasa, K. Yoshida, 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), 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), 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, Research unit Nuclear & Hadron Physics, 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), and Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)

Subjects
Nuclear and High Energy Physics, Nuclear Theory, n) reactions, Inverse-kinematics (p, n) reactions, 01 natural sciences, Low-energy neutron detector, Inverse-kinematics [formula omitted] reactions, Nuclear physics, 0103 physical sciences, Figure-of-Merit (FoM), Neutron detection, Neutron, 010306 general physics, Spin (physics), Nuclear Experiment, Instrumentation, Gamow-Teller transition, DETECTOR, Real-time pulse-shape discrimination, Physics, [PHYS]Physics [physics], Spin-isospin response, Spectrometer, 010308 nuclear & particles physics, Figure-of-Merit (RIM), Detector, PULSE-SHAPE DISCRIMINATION, PLASTIC SCINTILLATOR, Inverse-kinematics (p, Isospin, Ground state, Beam (structure)
Abstract

The status of a project to measure spin-isospin responses of neutron drip-line nuclei using a new low-energy neutron detector, PANDORA (Particle Analyzer Neutron Detector Of Real-time Acquisition), is reported. The performance of PANDORA was characterized by the 6He(p,n)6Li reaction in inverse kinematics at the HIMAC facility in Chiba. Observation of the strong transition to the ground state in 6Li is discussed. Preliminary results of 11Li(p,n)11Be and 14Be(p,n)14B experiments in inverse kinematics at RI Beam Factory (RIBF) of RIKEN Nishina Center are also presented including the exotic decay channel of 11Be→9Li + d. Details of the experimental setup based on PANDORA and the SAMURAI large-acceptance magnetic spectrometer, as well as the combined data-acquisition system are described. The neutron-gamma discrimination capability of PANDORA was evaluated, Figure-of-Merit (FoM) values higher than those found in the literature for similar materials were derived from experimental data.

Published
2020

25. New program for measuring masses of silver isotopes near the N = 82 shell closure with MLLTRAP at ALTO

Author

M. MacCormick, S. Franchoo, E. Minaya Ramirez, L. Perrot, P. G. Thirolf, P. Chauveau, A. Lopez-Martens, D. Lunney, J. Ljungvall, 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), and Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM)

Subjects
Physics, Nuclear and High Energy Physics, Proton, 010308 nuclear & particles physics, Nuclear Theory, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Mass spectrometry, Penning trap, 7. Clean energy, 01 natural sciences, Ion source, Nuclear physics, Radio-frequency quadrupole, 0103 physical sciences, Physics::Accelerator Physics, Nuclear binding energy, Neutron, Nuclide, Nuclear Experiment, 010306 general physics, Instrumentation, ComputingMilieux_MISCELLANEOUS
Abstract

The ISOL facility ALTO, located at Orsay in France, provides stable ion beams from a 15 MV Tandem accelerator and neutron-rich radioactive ion beams (RIB) from the interaction of a γ -flux induced by a 50 MeV 10 μA electron beam in a uranium carbide target. A magnetic dipole mass separator and a resonance ionization laser ion source allow to select the ions of interest. New setups are under preparation to extend the fundamental properties measured at ALTO of ground and excited states of exotic nuclei. For example, high-precision mass measurements for an accurate determination of the nuclear binding energy. To perform these measurements two devices will be hosted at ALTO: a radio frequency quadrupole to cool and bunch (RFQCB) the continuous radioactive beam and the double Penning trap mass spectrometer MLLTRAP, commissioned off-line at the Maier-Leibnitz Laboratory (MLL) in Garching, Germany. The unique production mechanism using photo-fission at the ALTO facility allows for mass measurements in a neutron rich area of nuclides of major interest around 132 Sn with less isobaric contamination than using proton drivers. In this context, we plan to measure neutron-rich silver isotopes (Z = 47, A > 121) to explore the possible weakening of the shell gap for Z

Published
2020

26. Resonance ionization schemes for high resolution and high efficiency studies of exotic nuclei at the CRIS experiment

Author

Xiaofei Yang, Fredrik Gustafsson, Shane Wilkins, Mark Bissell, Á. Koszorús, B. S. Cooper, C. L. Binnersley, A. R. Vernon, Thomas Elias Cocolios, R. F. Garcia Ruiz, S. Franchoo, Gerda Neyens, Kara Marie Lynch, J. Billowes, G. J. Farooq-Smith, Kieran Flanagan, H. Henry Stroke, W. Gins, C. M. Ricketts, V. N. Fedosseev, and R. P. de Groote

Subjects
Nuclear and High Energy Physics, High resolution, 7. Clean energy, 01 natural sciences, Resonance ionization spectroscopy, law.invention, Nuclear physics, law, Ionization, 0103 physical sciences, Dalton Nuclear Institute, Nuclear structure, Physics::Atomic Physics, Spectral resolution, 010306 general physics, Spectroscopy, Instrumentation, Physics, Large Hadron Collider, 010308 nuclear & particles physics, Delayed ionization, Laser, 3. Good health, ResearchInstitutes_Networks_Beacons/dalton_nuclear_institute, Resonance ionization, High-resolution laser spectroscopy
Abstract

© 2019 This paper presents an overview of recent resonance ionization schemes used at the Collinear Resonance Ionization Spectroscopy (CRIS) setup located at ISOLDE, CERN. The developments needed to reach high spectral resolution and efficiency will be discussed. Besides laser ionization efficiency and high resolving power, experiments on rare isotopes also require low-background conditions. Ongoing developments that aim to deal with beam-related sources of background are presented. ispartof: Nuclear Instruments & Methods In Physics Research Section B-Beam Interactions With Materials And Atoms vol:463 pages:398-402 ispartof: location:SWITZERLAND, CERN, Geneva status: published

Published
2020

27. γ -ray spectroscopy of low-lying yrast and non-yrast states in neutron-rich Kr94,95,96

Author

R.-B. Gerst, A. Blazhev, K. Moschner, P. Doornenbal, A. Obertelli, K. Nomura, J.-P. Ebran, S. Hilaire, J. Libert, G. Authelet, H. Baba, D. Calvet, F. Château, S. Chen, A. Corsi, A. Delbart, J.-M. Gheller, A. Giganon, A. Gillibert, V. Lapoux, T. Motobayashi, M. Niikura, N. Paul, J.-Y. Roussé, H. Sakurai, C. Santamaria, D. Steppenbeck, R. Taniuchi, T. Uesaka, T. Ando, T. Arici, F. Browne, A. M. Bruce, R. Caroll, L. X. Chung, M. L. Cortés, M. Dewald, B. Ding, F. Flavigny, S. Franchoo, M. Górska, A. Gottardo, J. Jolie, A. Jungclaus, J. Lee, M. Lettmann, B. D. Linh, J. Liu, Z. Liu, C. Lizarazo, S. Momiyama, S. Nagamine, N. Nakatsuka, C. R. Nita, C. Nobs, L. Olivier, R. Orlandi, Z. Patel, Zs. Podolyák, M. Rudigier, T. Saito, C. Shand, P.-A. Söderström, I. Stefan, V. Vaquero, V. Werner, K. Wimmer, and Z. Xu

Published
2022

28. Neutron-proton pairing in the N=Z radioactive fp-shell nuclei $^{56}$Ni and $^{52}$Fe probed by pair transfer

Author

B. Le Crom, M. Assié, Y. Blumenfeld, J. Guillot, H. Sagawa, T. Suzuki, M. Honma, N.L. Achouri, B. Bastin, R. Borcea, W.N. Catford, E. Clément, L. Cáceres, M. Caamaño, A. Corsi, G. De France, F. Delaunay, N. De Séréville, B. Fernandez-Dominguez, M. Fisichella, S. Franchoo, A. Georgiadou, J. Gibelin, A. Gillibert, F. Hammache, O. Kamalou, A. Knapton, V. Lapoux, S. Leblond, A.O. Macchiavelli, F.M. Marqués, A. Matta, L. Ménager, P. Morfouace, N.A. Orr, J. Pancin, X. Pereira-Lopez, L. Perrot, J. Piot, E. Pollacco, D. Ramos, T. Roger, F. Rotaru, A.M. Sánchez-Benítez, M. Sénoville, O. Sorlin, M. Stanoiu, I. Stefan, C. Stodel, D. Suzuki, J.-C. Thomas, M. Vandebrouck, Laboratoire de Physique des 2 Infinis Irène Joliot-Curie (IJCLab), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), 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), 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), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), and 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)

Subjects
Nuclear and High Energy Physics, Nuclear Theory, Direct reactions, FOS: Physical sciences, Radioactive beam, Neutron-proton pairing, 22 Física, Nuclear Experiment (nucl-ex), [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment, Cooper pairs
Abstract

The isovector and isoscalar components of neutron-proton pairing are investigated in the N=Z unstable nuclei of the \textit{fp}-shell through the two-nucleon transfer reaction (p,$^3$He) in inverse kinematics. The combination of particle and gamma-ray detection with radioactive beams of $^{56}$Ni and $^{52}$Fe, produced by fragmentation at the GANIL/LISE facility, made it possible to carry out this study for the first time in a closed and an open-shell nucleus in the \textit{fp}-shell. The transfer cross-sections for ground-state to ground-state (J=0$^+$,T=1) and to the first (J=1$^+$,T=0) state were extracted for both cases together with the transfer cross-section ratios $\sigma$(0$^+$,T=1) /$\sigma$(1$^+$,T=0). They are compared with second-order distorted-wave born approximation (DWBA) calculations. The enhancement of the ground-state to ground-state pair transfer cross-section close to mid-shell, in $^{52}$Fe, points towards a superfluid phase in the isovector channel. For the "deuteron-like" transfer, very low cross-sections to the first (J=1$^+$,T=0) state were observed both for \Ni\phe\, and \Fe\phe\, and are related to a strong hindrance of this channel due to spin-orbit effect. No evidence for an isoscalar deuteron-like condensate is observed., Comment: 7 pages, 4 figures

Published
2022

29. Experimental Level Scheme of \(^{78}\)Cu

Author

L.G. Pedersen, E. Sahin, A. Görgen, F.L. Bello Garrote, Y. Tsunoda, T. Otsuka, M. Niikura, S. Nishimura, Z. Xu, H. Baba, G. Benzoni, F. Browne, A.M. Bruce, S. Ceruti, F.C.L. Crespi, R. Daido, G. de Angelis, M.-C. Delattre, Zs. Dombradi, P. Doornenbal, Y. Fang, S. Franchoo, G. Gey, A. Gottardo, T. Isobe, P.R. John, H.S. Jung, I. Kojouharov, T. Kubo, N. Kurz, I. Kuti, Z. Li, G. Lorusso, I. Matea, K. Matsui, D. Mengoni, T. Miyazaki, V. Modamio, S. Momiyama, A.I. Morales, P. Morfouace, D.R. Napoli, F. Naqvi, H. Nishibata, A. Odahara, R. Orlandi, Z. Patel, S. Rice, H. Sakurai, H. Schaffner, L. Sinclair, P.-A. Söderström, D. Sohler, I.G. Stefan, T. Sumikama, D. Suzuki, R. Taniuchi, J. Taprogge, Z. Vajta, J.J. Valiente-Dobón, H. Watanabe, V. Werner, J. Wu, A. Yagi, M. Yalcinkaya, R. Yokoyama, and K. Yoshinaga

Subjects
General Physics and Astronomy
Published
2023

30. Structure of ^{36}Ca under the Coulomb Magnifying Glass

Author

L, Lalanne, O, Sorlin, A, Poves, M, Assié, F, Hammache, S, Koyama, D, Suzuki, F, Flavigny, V, Girard-Alcindor, A, Lemasson, A, Matta, T, Roger, D, Beaumel, Y, Blumenfeld, B A, Brown, F De Oliveira, Santos, F, Delaunay, N, de Séréville, S, Franchoo, J, Gibelin, J, Guillot, O, Kamalou, N, Kitamura, V, Lapoux, B, Mauss, P, Morfouace, M, Niikura, J, Pancin, T Y, Saito, C, Stodel, and J-C, Thomas

Abstract

Detailed spectroscopy of the neutron-deficient nucleus ^{36}Ca was obtained up to 9 MeV using the ^{37}Ca(p,d)^{36}Ca and the ^{38}Ca(p,t)^{36}Ca transfer reactions. The radioactive nuclei, produced by the LISE spectrometer at GANIL, interacted with the protons of the liquid hydrogen target CRYPTA, to produce light ejectiles (the deuteron d or triton t) that were detected in the MUST2 detector array, in coincidence with the heavy residues identified by a zero-degree detection system. Our main findings are (i) a similar shift in energy for the 1_{1}^{+} and 2_{1}^{+} states by about -250 keV, as compared with the mirror nucleus ^{36}S; (ii) the discovery of an intruder 0_{2}^{+} state at 2.83(13) MeV, which appears below the first 2^{+} state, in contradiction with the situation in ^{36}S; and (iii) a tentative 0_{3}^{+} state at 4.83(17) MeV, proposed to exhibit a bubble structure with two neutron vacancies in the 2s_{1/2} orbit. The inversion between the 0_{2}^{+} and 2_{1}^{+} states is due to the large mirror energy difference (MED) of -516(130) keV for the former. This feature is reproduced by shell model calculations, using the sd-pf valence space, predicting an almost pure intruder nature for the 0_{2}^{+} state, with two protons (neutrons) being excited across the Z=20 magic closure in ^{36}Ca (^{36}S). This mirror system has the largest MEDs ever observed, if one excludes the few cases induced by the effect of the continuum.

Published
2021

31. Investigation of the ground-state spin inversion in the neutron-rich Cl47,49 isotopes

Author

Jason D. Holt, Carlo Barbieri, Zaihong Yang, I. Murray, D. M. Rossi, K. I. Hahn, S. Y. Park, C. Hilaire, Kazuyuki Ogata, C. Lehr, H. Baba, Duo Yan, David Steppenbeck, H. Törnqvist, P. Koseoglou, Masahiro Yasuda, V. Lapoux, Yasuhiro Togano, N. L. Achouri, R.-B. Gerst, Alessandra Corsi, T. Lokotko, B. D. Linh, L. Stuhl, H. Wang, Dóra Sohler, M. Gómez-Ramos, Igor Gašparić, H. N. Liu, Y. L. Sun, Takashi Nakamura, E. Sahin, Petr Navrátil, V. Panin, W. Rodriguez, N. Shimizu, J. M. Gheller, A. Moro, Victor Vaquero, L. X. Chung, Thomas Duguet, K. Moschner, Hiroyoshi Sakurai, Kathrin Wimmer, Dong-Wook Kim, A. Delbart, N. T. Khai, V. Wagner, N. Paul, P. Doornenbal, T. Motobayashi, V. Somà, D. Calvet, T. Isobe, K. Yoneda, O. Aktas, V. Werner, Y. Yamada, Thomas Aumann, F. Flavigny, N. D. Ton, T. Kobayashi, A. Giganon, X. X. Xu, F. Château, Hideaki Otsu, Julien Gibelin, Si-Ge Chen, N. T. T. Phuc, P. A. Söderström, A. Gillibert, Nobuyuki Chiga, A. Obertelli, T. Koiwai, Tomohiro Uesaka, F. Browne, M. MacCormick, Satoshi Takeuchi, M. L. Cortés, Masaki Sasano, S. Franchoo, Yutaka Utsuno, Jenny Lee, Yuya Kubota, L. Zanetti, and Yosuke Kondo

Subjects
Physics, Isotope, 010308 nuclear & particles physics, 0103 physical sciences, Neutron, Atomic physics, 010306 general physics, Spin (physics), Ground state, 01 natural sciences, Inversion (discrete mathematics), Nuclear theory
Published
2021

32. Coulomb and nuclear excitations of Zn70 and Ni68 at intermediate energy

Author

G. de Angelis, J. Mrazek, L. Perrot, R. Borcea, R. Astabatyan, F. Carstoiu, H. Guerin, M. Stanoiu, T. Roger, S. Grévy, L. Stuhl, C. Petrone, Zs. Podolyák, M. N. Harakeh, A. Lepailleur, J. C. Thomas, L. Cáceres, D. D. Dao, I. Stefan, F. Negoita, M. Krzysiek, A. Gottardo, V. Maslov, S. Bagchi, C. Borcea, Dóra Sohler, I. Matea, O. Wieland, Z. Vajta, F. Nowacki, M. Vandebrouck, P. Morfouace, F. Rotaru, S. Lukyanov, I. Kuti, O. Sorlin, Megumi Niikura, S. Franchoo, A. Krasznahorkay, K. Mazurek, Y. Penionzhkevich, M. Ciemála, A. Maj, Zsolt Dombrádi, C. Rigollet, M. Kmiecik, I. M. Harca, Eric Clément, O. Kamalou, S. Calinescu, and L. Olivier

Subjects
Physics, Proton, 010308 nuclear & particles physics, Prolate spheroid, 01 natural sciences, Spectral line, Intermediate energy, 0103 physical sciences, Oblate spheroid, Coulomb, Atomic physics, 010306 general physics, Beam energy, Excitation
Abstract

The reduced transition probabilities B ( E 2 ; 0 g.s. + → 2 1 + , 2 2 + ) in Zn 70 and the full B ( E 2 ; 0 g.s. + → 2 + ) strength up to S n = 7.79 MeV in Ni 68 have been determined at the LISE/GANIL facility using the Coulomb-excitation technique at intermediate beam energy on a Pb 208 target. The γ rays emitted in-flight were detected with an array of 46 BaF 2 crystals. The angles of the deflected nuclei were determined in order to disentangle and extract the Coulomb and nuclear contributions to the excitation of the 2 + states. The measured B ( E 2 ; 0 g.s. + → 2 1 + ) of 1432(124) e 2 fm 4 for Zn 70 falls in the lower part of the published values which clustered either around 1600 or above 2000 e 2 fm 4 , while the B ( E 2 ; 0 g.s. + → 2 2 + ) of 53(7) e 2 fm 4 agrees very well with the two published values. The relatively low B ( E 2 ; 0 g.s. + → 2 1 + ) of 301(38) e 2 fm 4 for Ni 68 agrees with previous studies and confirms a local magicity at Z = 28 , N = 40 . Combining the results of the low-energy spectra of Ni 68 and Zn 70 and their shell-model interpretations, it is interesting to notice that four different shapes (spherical, oblate, prolate, and triaxial) are present. Finally, a summed E 2 strength of only about 150 e 2 fm 4 has been found experimentally at high excitation energy, likely due to proton excitations across the Z = 28 gap. The experimental distribution of this high-energy E 2 excitation agrees with shell-model calculations, but its strength is about two times weaker.

Published
2021

33. Persistence of the Z=28 shell gap in A=75 isobars: Identification of a possible (1/2−) μs isomer in Co75 and β decay to Ni75

Author

Hiroki Nishibata, A. I. Morales, Hirofumi Watanabe, Shin-Ichiro Nishimura, Megumi Niikura, Daisuke Suzuki, H. S. Jung, V. Werner, Ryo Taniuchi, D. Sohler, D. R. Napoli, Jan Taprogge, T. Isobe, N. Kurz, I. Kojouharov, Toshiyuki Sumikama, Jinguang Wu, P. A. Söderström, Ayumi Yagi, I. Matea, P. Morfouace, P. R. John, S. Franchoo, Shigeru Kubono, S. Escrig, F. Naqvi, Alfredo Poves, Atsuko Odahara, K. Matsui, Giuseppe Lorusso, H. Baba, Hiroyoshi Sakurai, Zhengyu Xu, Z. H. Li, E. Sahin, P. Doornenbal, D. Mengoni, Zs. Vajta, H. Schaffner, K. Yoshinaga, I. Stefan, F. Browne, and Guillaume Gey

Subjects
Physics, Proton, 010308 nuclear & particles physics, Center (category theory), Nuclear structure, Nuclear isomer, 7. Clean energy, 01 natural sciences, Spectral line, Nuclear physics, Nucleosynthesis, Excited state, 0103 physical sciences, Isobar, 010306 general physics
Abstract

Background: The evolution of shell structure around doubly-magic exotic nuclei is of great interest in nuclear physics and astrophysics. In the `south-west' region of $^{78}$Ni, the development of deformation might trigger a major shift in our understanding of explosive nucleosynthesis. To this end, new spectroscopic information on key close-lying nuclei is very valuable. Purpose: We intend to measure the isomeric and $\beta$ decay of $^{75}$Co, with one proton- and two neutron-holes relative to $^{78}$Ni, to access new nuclear structure information in $^{75}$Co and its $\beta$-decay daughters $^{75}$Ni and $^{74}$Ni. Methods: The nucleus $^{75}$Co is produced in relativistic in-flight fission reactions of $^{238}$U at the Radioactive Ion Beam Factory (RIBF) in the RIKEN Nishina Center. Its isomeric and $\beta$ decay are studied exploiting the BigRIPS and EURICA setups. Results: We obtain partial $\beta$-decay spectra for $^{75}$Ni and $^{74}$Ni, and report a new isomeric transition in $^{75}$Co. The energy ($E_{\gamma}=1914(2)$ keV) and half-life ($t_{1/2}=13(6)$ $\mu$s) of the delayed $\gamma$ ray lend support for the existence of a $J^{\pi}=(1/2^-)$ isomeric state at 1914(2) keV. A comparison with PFSDG-U shell-model calculations provides good account for the observed states in $^{75}$Ni, but the first calculated $1/2^-$ level in $^{75}$Co, a prolate $K=1/2$ state, is predicted about 1 MeV below the observed $(1/2^-)$ level. Conclusions: The spherical-like structure of the lowest-lying excited states in $^{75}$Ni is proved. In the case of $^{75}$Co, the results suggest that the dominance of the spherical configurations over the deformed ones might be stronger than expected below $^{78}$Ni. Further experimental efforts to discern the nature of the $J^{\pi}=(1/2^-)$ isomer are necessary.

Published
2021

34. Pairing Forces Govern Population of Doubly Magic Ca54 from Direct Reactions

Author

J. M. Gheller, S. Y. Park, K. Yoneda, Masaki Sasano, P. A. Söderström, D. Sohler, D. Körper, H. Simon, A. Gillibert, K. Miki, Satoshi Takeuchi, Yasuhiro Togano, M. MacCormick, R.-B. Gerst, Duo Yan, Tomohiro Uesaka, Fabia Schindler, V. Wagner, B. D. Linh, M. Holl, A. Corsi, N. Paul, Igor Gašparić, H. N. Liu, P. Koseoglou, E. Sahin, Yosuke Kondo, T. Lokotko, T. Isobe, Victor Vaquero, M. L. Cortés, V. Werner, Takashi Nakamura, W. Rodriguez, Zaihong Yang, A. Delbart, S. Franchoo, F. Château, V. Lapoux, P. Doornenbal, K. I. Hahn, L. Stuhl, I. Murray, C. Caesar, Kazuyuki Ogata, C. Lehr, T. Kobayashi, X. X. Xu, C. Hilaire, Si-Ge Chen, Yutaka Utsuno, V. Panin, A. Giganon, Jenny Lee, N. L. Achouri, L. X. Chung, Y. L. Sun, K. Moschner, Yuya Kubota, D. M. Rossi, H. Baba, F. Flavigny, Masahiro Yasuda, L. Zanetti, Kathrin Wimmer, Dong-Wook Kim, O. Aktas, F. Browne, S. Wang, A. Obertelli, J. Kahlbow, Hiroyoshi Sakurai, T. Motobayashi, Julien Gibelin, K. Boretzky, D. Calvet, David Steppenbeck, H. Törnqvist, Thomas Aumann, Nobuyuki Chiga, T. Koiwai, Kazuki Yoshida, Hideaki Otsu, Hirofumi Yamada, and J. Tscheuschner

Subjects
Physics, education.field_of_study, Proton, 010308 nuclear & particles physics, Nuclear Theory, Population, Nuclear shell model, General Physics and Astronomy, 01 natural sciences, 7. Clean energy, Pairing, Excited state, 0103 physical sciences, Neutron, Atomic physics, Nuclear Experiment, 010306 general physics, Nucleon, Ground state, education
Abstract

Direct proton-knockout reactions of ^{55}Sc at ∼220 MeV/nucleon were studied at the RIKEN Radioactive Isotope Beam Factory. Populated states of ^{54}Ca were investigated through γ-ray and invariant-mass spectroscopy. Level energies were calculated from the nuclear shell model employing a phenomenological internucleon interaction. Theoretical cross sections to states were calculated from distorted-wave impulse approximation estimates multiplied by the shell model spectroscopic factors, which describe the wave function overlap of the ^{55}Sc ground state with states in ^{54}Ca. Despite the calculations showing a significant amplitude of excited neutron configurations in the ground-state of ^{55}Sc, valence proton removals populated predominantly the ground state of ^{54}Ca. This counterintuitive result is attributed to pairing effects leading to a dominance of the ground-state spectroscopic factor. Owing to the ubiquity of the pairing interaction, this argument should be generally applicable to direct knockout reactions from odd-even to even-even nuclei.

Published
2021

35. First spectroscopic study of V63 at the N=40 island of inversion

Author

K. Moschner, David Steppenbeck, F. Browne, Jenny Lee, H. Törnqvist, Y. L. Sun, Kathrin Wimmer, Yuya Kubota, A. Gillibert, V. Panin, E. Sahin, L. X. Chung, D. Calvet, T. Isobe, Alessandra Corsi, Dóra Sohler, R.-B. Gerst, M. MacCormick, Yosuke Kondo, F. Château, Hideaki Otsu, P. Doornenbal, Hirofumi Yamada, N. Paul, V. Werner, Satoshi Takeuchi, M. L. Cortés, Masahiro Yasuda, D. M. Rossi, S. Franchoo, C. Lehr, W. Rodriguez, H. Baba, S. Y. Park, Z. Elekes, A. Giganon, Kazuyuki Ogata, Nobuyuki Chiga, Duo Yan, T. Lokotko, L. Zanetti, L. Stuhl, K. Yoneda, T. Koiwai, Takashi Nakamura, A. Delbart, Masaki Sasano, N. L. Achouri, S. Wang, B. D. Linh, Igor Gašparić, H. N. Liu, Yasuhiro Togano, V. Wagner, P. Koseoglou, F. Flavigny, J. M. Gheller, Tomohiro Uesaka, A. Obertelli, Zs. Dombrádi, Hiroyoshi Sakurai, T. Motobayashi, Julien Gibelin, Dong-Wook Kim, O. Aktas, V. Lapoux, K. Yoshida, M. M. Juhász, Kamila Sieja, Zaihong Yang, I. Murray, K. I. Hahn, T. Kobayashi, X. X. Xu, Si-Ge Chen, P. A. Söderström, Victor Vaquero, Thomas Aumann, and C. Hilaire

Subjects
Physics, 010308 nuclear & particles physics, Island of inversion, 0103 physical sciences, Geophysics, 010306 general physics, 01 natural sciences
Published
2021

36. Inclusive cross sections for one- and multi-nucleon removal from Sn, Sb, and Te projectiles beyond the N = 82 shell closure

Author

Hiroyoshi Sakurai, Megumi Niikura, F. L. Bello Garrote, Gry Merete Tveten, S. Franchoo, Yoshiaki Shiga, David Steppenbeck, Zs. Vajta, A. Jungclaus, M. Yalcinkaya, Pieter Doornenbal, K. Hadynska-Klek, JJ Liu, R. Orlandi, Hidetada Baba, S. Nagamine, Ryo Taniuchi, Enrique Nácher, Nathan Nakatsuka, Victor Vaquero, E. Sahin, Kathrin Wimmer, A. Kusoglu, J. A. Tostevin, A. Gargano, T. Lokotko, Toshiaki Ando, Si-Ge Chen, P. A. Söderström, Tohru Motobayashi, Zhengyu Xu, T. Saito, J. L. Rodriguez-Sanchez, Satoru Momiyama, RIKEN Nishina Center for Accelerator-Based Science, Ministerio de Economía y Competitividad (España), Ministerio de Ciencia, Innovación y Universidades (España), Science and Technology Facilities Council (UK), Japan Society for the Promotion of Science, Research Council of Norway, SCOAP, 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), 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, Isotope, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], 010308 nuclear & particles physics, Fission, Projectile, Nuclear Theory, Shell (structure), 01 natural sciences, lcsh:QC1-999, Nuclear physics, Cross section (physics), Inclusive knockout cross sections, 13. Climate action, 0103 physical sciences, Neutron, 010306 general physics, Nucleon, Eikonal reaction theory, Nuclear Experiment, Beam (structure), lcsh:Physics, Intranuclear cascade model
Abstract

6 pags., 4 figs., 1 tab.-- Open Access funded by Creative Commons Atribution Licence 4.0, Inclusive one- and multi-nucleon removal cross sections have been measured for several Sn, Sb and Te isotopes just beyond the N=82 neutron shell closure. The beams were produced in the projectile fission of a U beam at the Radioactive Isotope Beam Factory at RIKEN. The experimental cross sections are compared to predictions from the most recent version of the Liege intranuclear cascade model. Although the overall agreement is good, severe discrepancies are observed for the cases of one- and two-neutron removal from Sn and Sb projectiles and one-proton knockout from all measured N=84 isotones. These discrepancies, as well as the relevance of quasi-elastic reaction channels to the one-neutron removal cross sections, are discussed. In addition, the measured inclusive one-proton knockout cross section for the semi-magic Sn projectile is compared to eikonal direct reaction theory calculations to assess if the suppression factors to these calculated cross sections, deduced from data on reactions of lighter projectile nuclei, are also applicable to heavy nuclei., We thank the staff of the RIKEN Nishina Center accelerator complex for providing high-intensity beams to the experiment. This work was supported by the Spanish Ministerio de Economía y Competitividad under contracts FPA2014-57196-C5-4-P and FPA2017-84756-C4-2-P. J.A.T. acknowledges the support of the Science and Technology Facilities Council (UK) grant ST/L005314/1 and R.O. that of JSPS KAKENHI Grant No. 26887048. G.M.T. grate-fully acknowledges funding of this research from the Research Council of Norway, Project Grant No. 222287.

Published
2019

37. Low-energy experiments at the S3 spectromet

Author

S. Franchoo

Subjects
Low energy, Materials science, Nuclear Experiment, Computational physics
Abstract

With the advent of the Spiral-2 linear accelerator and the associated S3 spectrometer at the Ganil laboratory in France, new realms of intermediate-mass N=Z and very heavy nuclei will soon become available for research in nuclear structure. After their production and selection in the spectrometer, the ions of interest will be stopped in a buffer gas, neutralised, resonantly re-ionised, cooled and bunched. This will bring us in an adequate position to perform laser spectroscopy, mass measurements and decay spectroscopy of their ground and isomeric states. In this contribution we report on the ongoing commissioning of the detector set-up.

Published
2019

38. Evaluation of the K35(p,γ)Ca36 reaction rate using the Ca37(p,d)Ca36 transfer reaction

Author

J. Pancin, L. Lalanne, Tomoki Saito, Franck Delaunay, Julien Gibelin, Megumi Niikura, B. Mauss, A. Lemasson, Daisuke Suzuki, N. Kitamura, O. Sorlin, Didier Beaumel, Jérôme Guillot, J. C. Thomas, André Palma da Cunha Matta, P. Morfouace, F. de Oliveira Santos, S. Franchoo, C. Stodel, A. Poves, N. de Sereville, M. Assié, F. Hammache, Y. Blumenfeld, F. Flavigny, V. Lapoux, O. Kamalou, V. Girard-Alcindor, B. A. Brown, Shoko Koyama, and T. Roger

Subjects
Physics, Range (particle radiation), Proton, 010308 nuclear & particles physics, Resonance, Light curve, 01 natural sciences, 7. Clean energy, Atomic mass, Charged particle, Reaction rate, Recoil, 0103 physical sciences, Atomic physics, Nuclear Experiment, 010306 general physics
Abstract

Background: A recent sensitivity study has shown that the K35(p,γ)Ca36 reaction is one of the ten (p,γ) reaction rates that could significantly impact the shape of the calculated x-ray burst light curve. Its reaction rate used up to now in type I x-ray burst calculations was estimated using an old measurement for the mass of Ca36 and theoretical predictions for the partial decay widths of the first 2+ resonance with arbitrary uncertainties. Purpose: In this work, we propose to reinvestigate the K35(p,γ)Ca36 reaction rate, as well as related uncertainties, by determining the energies and decay branching ratios of Ca36 levels, within the Gamow window of x-ray bursts, in the 0.5 to 2 GK temperature range. Method: These properties were studied by means of the one-neutron pickup transfer reaction Ca37(p,d)Ca36 in inverse kinematics using a radioactive beam of Ca37 at 48 MeV nucleon−1. The experiment was performed at the GANIL facility using the liquid hydrogen target CRYPTA, the MUST2 charged particle detector array for the detection of the light charged particles, and a zero degree detection system for the outgoing heavy recoil nuclei. Results: The atomic mass of Ca36 is confirmed and new resonances have been proposed together with their proton decay branching ratios. This spectroscopic information, used in combination with very recent theoretical predictions for the γ-decay width, were used to calculate the K35(p,γ)Ca36 reaction rate. The recommended rate of the present work was obtained within a uncertainty factor of 2 at 1σ. This is consistent with the previous estimate in the x-ray burst temperature range. A large increase of the reaction rate was found at higher temperatures due to two newly discovered resonances. Conclusions: The K35(p,γ)Ca36 thermonuclear reaction rate is now well constrained by the present work in a broad range of temperatures covering those relevant to type I x-ray bursts. Our results show that the K35(p,γ)Ca36 reaction does not affect the shape of the x-ray burst light curve, and that it can be removed from the list of the few influential proton radiative captures reactions having a strong impact on the light curve.

Published
2021

39. Sub-threshold states in Ne19 relevant to F18(p,α)O15

Author

Giuseppe Verde, Mark A. Williams, Alison Laird, M. Assié, R. Garg, S. Gillespie, Vincent Tatischeff, Anuj Parikh, A. Lefebvre-Schuhl, J. Riley, N. de Sereville, A. Remadi, S. Franchoo, N. J. Hubbard, C. Hamadache, I. Stefan, J. Kiener, F. Hammache, L. Perrot, B. Bastin, F. de Oliveira Santos, S. P. Fox, F. Boulay, Daisuke Suzuki, Valdir Guimaraes, P. Adsley, and A. Coc

Subjects
Physics, Thermonuclear fusion, Spin states, Proton, 010308 nuclear & particles physics, Parity (physics), 01 natural sciences, 7. Clean energy, Coincidence, Nuclear physics, Reaction rate, 0103 physical sciences, Sub threshold, Nuclear Experiment, 010306 general physics, Charge exchange
Abstract

Classical novae result from thermonuclear explosions producing several $\gamma$-ray emitters which are prime targets for satellites observing in the MeV range. The early 511 keV gamma-ray emission depends critically on the $^{18}$F(p,$\alpha$)$^{15}$O reaction rate which, despite many experimental and theoretical efforts, still remains uncertain. One of the main uncertainties in the $^{18}$F(p,$\alpha$)$^{15}$O reaction rate is the contribution in the Gamow window of interference between sub-threshold $^{19}$Ne states and known broad states at higher energies. Therefore the goal of this work is to clarify the existence and the nature of these sub-threshold states. States in the $^{19}$Ne compound nucleus were studied at the Tandem-ALTO facility using the $^{19}$F($^3$He,t)$^{19}$Ne charge exchange reaction. Tritons were detected with an Enge Split-pole spectrometer while decaying protons or $\alpha$-particles from unbound $^{19}$Ne states were collected, in coincidence, with a double-sided silicon strip detector array. Angular correlations were extracted and constraints on the spin and parity of decaying states established. The coincidence yield at $E_x$ = 6.29 MeV was observed to be high spin, supporting the conclusion that it is indeed a doublet consisting of high spin and low spin components. Evidence for a broad, low spin state was observed around 6 MeV. Branching ratios were extracted for several states above the proton threshold and were found to be consistent with the literature. R-matrix calculations show the relative contribution of sub-threshold states to the astrophysically important energy region above the proton threshold. The levels schemes of $^{19}$Ne and $^{19}$F are still not sufficiently well known and further studies of the analogue assignments are needed. The tentative broad state at 6 MeV may only play a role if the reduced proton width is large.

Published
2021

40. Isotope Shifts of Radium Monofluoride Molecules

Author

S. G. Wilkins, Alexander A. Breier, S. Franchoo, Sebastian Rothe, Thomas Elias Cocolios, H. A. Perrett, Xiaofei Yang, J. Billowes, Á. Koszorús, B. S. Cooper, K. Chrysalidis, C. L. Binnersley, Gerda Neyens, Robert Berger, Konstantin Gaul, T. A. Isaev, R. P. de Groote, R. F. Garcia Ruiz, C. M. Ricketts, Mark Bissell, Frank Wienholtz, Thomas F. Giesen, Silviu-Marian Udrescu, A. R. Vernon, Alex Brinson, Fredrik Gustafsson, Kieran Flanagan, Klaus Wendt, 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), 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 HEP, INSPIRE

Subjects
[PHYS.NUCL] Physics [physics]/Nuclear Theory [nucl-th], FIELD SHIFT, Nuclear Theory, Atomic Physics (physics.atom-ph), Ab initio, General Physics and Astronomy, NUCLEAR-STRUCTURE, nucl-ex, 01 natural sciences, Physics - Atomic Physics, 010305 fluids & plasmas, ENERGY, chemistry.chemical_compound, atomifysiikka, MOMENTS, Physics::Atomic Physics, Nuclear Experiment (nucl-ex), Nuclear Experiment, Physics, Isotope, Nuclear structure, radium, Nuclear Physics - Theory, Physical Sciences, Atomic physics, ydinfysiikka, nucl-th, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], Monofluoride, [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], [PHYS.PHYS.PHYS-GEN-PH] Physics [physics]/Physics [physics]/General Physics [physics.gen-ph], Physics, Multidisciplinary, Other Fields of Physics, FOS: Physical sciences, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], physics.atom-ph, Molecular electronic transition, ELECTRONIC-STRUCTURE CALCULATIONS, Nuclear Theory (nucl-th), ATOMS, 0103 physical sciences, Molecule, SPECTRA, Nuclear Physics - Experiment, Sensitivity (control systems), 010306 general physics, isotoopit, Science & Technology, [PHYS.PHYS.PHYS-GEN-PH]Physics [physics]/Physics [physics]/General Physics [physics.gen-ph], chemistry, MECHANICS, MASS DEPENDENCE, LASER, Electronic density
Abstract

Isotope shifts of $^{223-226,228}$Ra$^{19}$F were measured for different vibrational levels in the electronic transition $A^{2}{}{\Pi}_{1/2}\leftarrow X^{2}{}{\Sigma}^{+}$. The observed isotope shifts demonstrate the particularly high sensitivity of radium monofluoride to nuclear size effects, offering a stringent test of models describing the electronic density within the radium nucleus. Ab initio quantum chemical calculations are in excellent agreement with experimental observations. These results highlight some of the unique opportunities that short-lived molecules could offer in nuclear structure and in fundamental symmetry studies., Comment: The paper was accepted for publication as a Letter in Physical Review Letters

Published
2021

41. Coulomb and nuclear excitations of Zn 70 and Ni 68 at intermediate energy

Author

S. Calinescu, O. Sorlin, I. Matea, F. Carstoiu, D. D. Dao, F. Nowacki, G. de Angelis, R. Astabatyan, S. Bagchi, C. Borcea, R. Borcea, L. Cáceres, M. Ciemála, E. Clément, Z. Dombrádi, S. Franchoo, A. Gottardo, S. Grévy, H. Guerin, M. N. Harakeh, I. M. Harca, O. Kamalou, M. Kmiecik, A. Krasznahorkay, M. Krzysiek, I. Kuti, A. Lepailleur, S. Lukyanov, A. Maj, V. Maslov, K. Mazurek, P. Morfouace

Published
2021
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42. Probing nuclear forces beyond the nuclear drip line: the cases of $^{16}$F and $^{15}$F: A Tribute to Mahir Hussein

Author

L. Caceres, A.M. Sánchez Benítez, Igor T. Čeliković, A. Matta, D. Verney, F. Rotaru, Valdir Guimaraes, P. Adsley, O. Sorlin, J. Guillot, T. Roger, C. Portail, V. Girard-Alcindor, I. Matea, A. Georgiadou, C. Petrone, D. Pantelica, R. Borcea, D. Suzuki, O. Kamalou, V. Lapoux, Megumi Niikura, I. Stefan, J. Piot, F. Flavigny, G. D’Agata, F. de Oliveira Santos, M. Ciemala, V. Tatischeff, V. Chudoba, L. Lalanne, C. Stodel, J. C. Thomas, N. Goyal, M. Stanoiu, C. Fougeres, S. Grévy, F. Negoita, N. de Séréville, L. Perrot, G. Dumitru, M. Assie, A. Meyer, J. C. Angelique, Marlete Assunção, Nicolas Michel, F. Hammache, D. Beaumel, S. Franchoo, Predrag Ujić, Dieter Ackermann, Shoko Koyama, F. de Grancey, J. Kiener, E. Berthoumieux, P. Morfouace, J. Mrazek, K. Subotic, 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), Laboratoire de Physique des 2 Infinis Irène Joliot-Curie (IJCLab), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), 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), 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)-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
Elastic scattering, Physics, Nuclear and High Energy Physics, Proton, 010308 nuclear & particles physics, media_common.quotation_subject, Hadron, Nuclear Theory, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Asymmetry, Excited state, 0103 physical sciences, Nuclear force, Mirror nuclei, Atomic physics, 010306 general physics, Wave function, Nuclear Experiment, media_common
Abstract

The unbound proton-rich nuclei $$^{16}$$ F and $$^{15}$$ F are investigated experimentally and theoretically. Several experiments using the resonant elastic scattering method were performed at GANIL with radioactive beams to determine the properties of the low lying states of these nuclei. Strong asymmetry between $$^{16}$$ F– $$^{16}$$ N and $$^{15}$$ F– $$^{15}$$ C mirror nuclei is observed. The strength of the $$nucleon-nucleon$$ effective interaction involving the loosely bound proton in the $$s_{1/2}$$ orbit is significantly modified with respect to their mirror nuclei $$^{16}$$ N and $$^{15}$$ C. The reduction of the effective interaction is estimated by calculating the interaction energies with a schematic zero-range force. It is found that, after correcting for the effects due to changes in the radial distribution of the single-particle wave functions, the mirror symmetry of the $$n-p$$ interaction is preserved between $$^{16}$$ F and $$^{16}$$ N, while a difference of 63% is measured between the $$p-p$$ versus $$n-n$$ interactions in the second excited state of $$^{15}$$ F and $$^{15}$$ C nuclei. Several explanations are proposed.

Published
2021

43. First spectroscopic study of $^{51}$Ar by the (p,2p) reaction

Author

Zs. Dombradi, S. Y. Park, T. Isobe, F. Browne, K. Moschner, Thomas Aumann, R.-B. Gerst, F. Château, Kathrin Wimmer, X. X. Xu, Z. Elekes, L. Zanetti, Hideaki Otsu, B. D. Linh, Hirofumi Yamada, Si-Ge Chen, P. A. Söderström, Yutaka Utsuno, Igor Gašparić, H. N. Liu, Jenny Lee, Zaihong Yang, I. Murray, Yasuhiro Togano, F. Flavigny, K. I. Hahn, L. Stuhl, Yuya Kubota, V. Wagner, Tomohiro Uesaka, A. Giganon, D. Kim, M. MacCormick, C. Lehr, V. Panin, L. X. Chung, P. Koseoglou, T. Lokotko, Y.L. Sun, E. Sahin, K. Yoneda, Victor Vaquero, M. L. Cortés, Takashi Nakamura, S. Franchoo, P. Doornenbal, Satoshi Takeuchi, Masahiro Yasuda, O. Aktas, A. Gillibert, V. Lapoux, Nobuyuki Chiga, Takaharu Otsuka, T. Koiwai, Hiroyoshi Sakurai, T. Motobayashi, M. M. Juhász, Kazuki Yoshida, David Steppenbeck, Julien Gibelin, H. Törnqvist, Toshio Kobayashi, Kazuyuki Ogata, W. Rodriguez, N. L. Achouri, C. Hilaire, S. Wang, Donghang Yan, N. Paul, A. Obertelli, J. M. Gheller, Yosuke Kondo, V. Werner, D. Calvet, D. M. Rossi, Masaki Sasano, H. Baba, D. Sohler, A. Corsi, A. Delbart, 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), 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), Normandie Université (NU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), RIKEN Nishina Center for Accelerator-Based Science, European Research Council, European Commission, Helmholtz International Center for FAIR, German Research Foundation, Alexander von Humboldt Foundation, Ministry of Science and Technology of Vietnam, Government of South Korea, Agencia Estatal de Investigación (España), Federal Ministry of Education and Research (Germany), Helmholtz Graduate School for Hadron and Ion Research, and National Research, Development and Innovation Office (Hungary)

Subjects
Nuclear and High Energy Physics, Shell closure, γ -ray spectroscopy, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, 0103 physical sciences, Bound state, nuclear shell model, proton knock-out reaction, gamma-ray spectroscopy, invariant-mass method, radioactive beams, Invariant mass, Neutron, ddc:530, Nuclear structure, 010306 general physics, Spectroscopy, Physics, Valence (chemistry), Proton knock-out reaction, 010308 nuclear & particles physics, Invariant mass method, Isotopes of argon, lcsh:QC1-999, Excited state, γ-ray spectroscopy, Atomic physics, lcsh:Physics
Abstract

8 pags., 4 figs., 3 tabs., 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., We are very grateful to the RIKEN Nishina Center accelerator staff for providing the stable beam and to the BigRIPS team for the smooth operation of the secondary beams. The development of the MINOS device has been supported by the European Research Council through the ERC Grant No. MINOS-258567. F. B. was supported by the RIKEN Special Postdoctoral Researcher Program. K. O. acknowledges the support by Grant-in-Aid for Scientific Research JP16K05352. Y. U. acknowledges the support by Grant-in-Aid for Scientific Research 20K03981. Y. L. S. acknowledges the support of Marie Skłodowska-Curie Individual Fellowship (H2020-MSCA-IF-2015-705023) from the European Union and the support from the Helmholtz International Center for FAIR. H. N. L. acknowledges the support from the Enhanced Eurotalents program (PCOFUND-GA-2013-600382) co-funded by CEA and the European Union. T. A., C. L., D. R., H. T., V. W., L. Z., H. N. L., V. W. and A. O. acknowledge the support from the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) Project No. 279384907-SFB 1245. R. B. G. acknowledges the support from the DFG under Grant No. BL 1513/1-1. Y. L. S. and A. O. acknowledge the support from the Alexander von Humboldt Foundation. B. D. L. and L. X. C. acknowledge the support from the Vietnam Ministry of Science and Technology under Grant No. ĐTCB.01/21/VKHKTHN. I. G. has been supported by HIC for FAIR and HRZZ under project No. 1257 and 7194. K. I. H., D. K. and S. Y. P. acknowledge the support from the NRF grant funded by the Korea government (No. 2017R1A2B2012382 and 2019M7A1A1033186). F. B. acknowledge the support from the RIKEN Special Postdoctoral Researcher Program. D. S. and Z. E. were supported by projects No. GINOP-2.3.3-15-2016-00034 and No. K128947. V. V. acknowledges support from the Spanish Ministerio de Economía y Competitividad under Contract No. FPA2017-84756-C4-2-P. V. W. and P. K. acknowledge the support from BMBF grants 05P15RDFN1 and 05P19RDFN1. P. K. acknowledges support from HGS-HIRe. This work was also supported by NKFIH (114454).

Published
2021

44. N=32 shell closure below calcium: Low-lying structure of Ar50

Author

Nobuyuki Chiga, K. Moschner, T. Koiwai, Hiroyoshi Sakurai, V. Lapoux, A. Gillibert, Yutaka Utsuno, D. Calvet, T. Isobe, Kathrin Wimmer, T. Motobayashi, Jenny Lee, Achim Schwenk, H. Toernqvist, Yuya Kubota, Victor Vaquero, R.-B. Gerst, F. Château, W. Rodriguez, N. Shimizu, B. D. Linh, D. M. Rossi, Masahiro Yasuda, Tomohiro Uesaka, Hideaki Otsu, Igor Gašparić, H. N. Liu, V. Panin, H. Baba, Kazuyuki Ogata, L. X. Chung, S. Y. Park, Julien Gibelin, Hirofumi Yamada, K. Yoshida, C. Lehr, Duo Yan, L. Achouri, Zaihong Yang, L. Stuhl, A. Giganon, I. Murray, S. Wang, N. Paul, L. Zanetti, E. Sahin, Y. L. Sun, J. Simonis, A. Obertelli, K. Yoneda, C. Hilaire, K. I. Hahn, V. Werner, David Steppenbeck, Jason D. Holt, P. Doornenbal, A. Delbart, M. MacCormick, P. Koseoglou, J. M. Gheller, Alessandra Corsi, Thomas Aumann, Masaki Sasano, Dóra Sohler, Satoshi Takeuchi, M. L. Cortés, S. Franchoo, T. Kobayashi, F. Flavigny, X. X. Xu, Si-Ge Chen, P. A. Söderström, Dong-Wook Kim, F. Browne, O. Aktas, Yosuke Kondo, Yasuhiro Togano, T. Lokotko, Takashi Nakamura, Javier Fernandez Menendez, and V. Wagner

Subjects
Physics, 010308 nuclear & particles physics, 0103 physical sciences, Closure (topology), Shell (structure), Calcium low, 010306 general physics, 01 natural sciences, Molecular physics
Published
2020

45. Erratum: β -delayed fission of Tl180 [Phys. Rev. C 88 , 044321 (2013)]

Author

A. E. Barzakh, D. V. Fedorov, Thomas Elias Cocolios, Cyrillus Wagemans, I. Tsekhanovich, Marc Huyse, V. N. Fedosseev, V. F. Comas, J. A. Heredia, R. D. Page, O. Ivanov, P. Van den Bergh, J. Elseviers, S. Vermote, L. Ghys, N. Patronis, P. Van Duppen, M. D. Seliverstov, Ulli Köster, M. Venhart, B. A. Marsh, S. Antalic, S. Franchoo, J. Van de Walle, N. Bree, Jan Diriken, Katsuhisa Nishio, M. Veselský, and A. N. Andreyev

Subjects
Nuclear physics, Physics, Fission
Published
2020

46. Sequential Nature of (p,3p) Two-Proton Knockout from Neutron-Rich Nuclei

Author

Megumi Niikura, K. Yoneda, Tomohiro Uesaka, T. Miyazaki, J.-Y. Roussé, A. Jungclaus, I. G. Stefan, Masaki Sasano, A. Gillibert, Jian Liu, Hiroyoshi Sakurai, David Steppenbeck, Zs. Dombradi, K. Moschner, M. Gómez-Ramos, Satoshi Takeuchi, D. Calvet, T. Isobe, Shunji Nishimura, T. Saito, V. Lapoux, H. Wang, T. Motobayashi, L. Olivier, R. Lozeva, A. Gottardo, S. Franchoo, C. Péron, H. Baba, Jinguang Wu, G. Authelet, A. Delbart, A. Blazhev, J. M. Gheller, Hideaki Otsu, F. Château, Masafumi Matsushita, Zs. Vajta, Zena Patel, Victor Vaquero, Kathrin Wimmer, M. L. Cortés, K. Matsui, Shuichi Ota, C. Santamaria, E. C. Pollacco, M. Dewald, Alessandra Corsi, F. Browne, C. R. Nita, M. Rudigier, Z. Korkulu, Jenny Lee, Yoshiaki Shiga, K. Hadynska-Klek, S. Nagamine, Satoru Momiyama, A. Frotscher, T. Arici, Ryo Taniuchi, Noritaka Shimizu, C. R. Nobs, Toshiyuki Sumikama, Alison Bruce, C. Louchart, E. Sahin, Toshiaki Ando, Zhenci Xu, F. Giacoppo, Y. Kubota, L. X. Chung, B. D. Linh, P. Doornenbal, F. Flavigny, A. Giganon, N. Paul, C. M. Shand, Noritsugu Nakatsuka, Zi Hong Liu, V. Werner, M. Górska, Si-Ge Chen, P. A. Söderström, D. Suzuki, M. Lettmann, R. Orlandi, C. Lizarazo, A. Obertelli, Raymond J. Carroll, Bing Ding, Zs. Podolyák, Shoko Koyama, and Alan Peyaud

Subjects
Physics, Hydrogen, Proton, Projectile, Nuclear Theory, General Physics and Astronomy, chemistry.chemical_element, 01 natural sciences, Coincidence, Nuclear physics, medicine.anatomical_structure, chemistry, MINOS, 0103 physical sciences, medicine, Neutron, Nuclear Experiment, 010306 general physics, Nucleon, Nucleus
Abstract

Twenty-one two-proton knockout (p; 3p) cross sections from neutron-rich nuclei at ~ 250 MeV/nucleon were measured. For the first time, the angular distribution of the three emitted protons were measured in coincidence with the tracker and hydrogen target MINOS, demonstrating that the (p; 3p) kinematics is consistent with two sequential proton-proton collisions within the projectile nucleus. Ratios of (p; 3p) over (p; 2p) inclusive cross sections follow the trend of other many-proton (neutron) removal reactions, further reinforcing the sequential nature of (p; 3p) in neutron-rich nuclei.

Published
2020

47. Metastable States of Se92,94 : Identification of an Oblate K Isomer of Se94 and the Ground-State Shape Transition between N=58 and 60

Author

L. Olivier, I. Kojouharov, G. Authelet, J. M. Gheller, V. Lapoux, Jenny Lee, J.-Y. Roussé, J. Gerl, C. Lizarazo, N. Paul, Noritsugu Nakatsuka, Hiroyoshi Sakurai, H. Schaffner, P. M. Walker, Zi Hong Liu, V. Werner, David Steppenbeck, T. Motobayashi, A. Blazhev, P. Doornenbal, Shunji Nishimura, I. Stefan, M. L. Cortés, T. Arici, J. J. Liu, Tomás R. Rodríguez, Alison Bruce, A. Giganon, C. Santamaria, F. Château, Megumi Niikura, Zhengyu Xu, F. Browne, Tomohiro Uesaka, M. Rudigier, C. R. Niţă, P. A. Söderström, Zena Patel, T. Saito, N. Kurz, M. Górska, S. Franchoo, A. Gillibert, G. X. Dong, A. Gottardo, C. M. Shand, Satoru Momiyama, L. X. Chung, C. R. Nobs, B. D. Linh, S. Nagamine, Ryo Taniuchi, A. Obertelli, M. Dewald, K. Moschner, Kathrin Wimmer, H. Baba, R. J. Caroll, D. Calvet, F. Flavigny, Bing Ding, Zs. Podolyák, Furong Xu, Toshiaki Ando, Si-Ge Chen, Victor Vaquero, M. Lettmann, A. Corsi, Norbert Pietralla, and A. Delbart

Subjects
Physics, 010308 nuclear & particles physics, General Physics and Astronomy, chemistry.chemical_element, Germanium, 01 natural sciences, Hafnium, medicine.anatomical_structure, chemistry, Atomic orbital, Metastability, 0103 physical sciences, Physics::Atomic and Molecular Clusters, medicine, Neutron, Atomic physics, Nuclear Experiment, 010306 general physics, Ground state, Spectroscopy, Nucleus
Abstract

Here we present new information on the shape evolution of the very neutron-rich ^{92,94}Se nuclei from an isomer-decay spectroscopy experiment at the Radioactive Isotope Beam Factory at RIKEN. High-resolution germanium detectors were used to identify delayed γ rays emitted following the decay of their isomers. New transitions are reported extending the previously known level schemes. The isomeric levels are interpreted as originating from high-K quasineutron states with an oblate deformation of β∼0.25, with the high-K state in ^{94}Se being metastable and K hindered. Following this, ^{94}Se is the lowest-mass neutron-rich nucleus known to date with such a substantial K hindrance. Furthermore, it is the first observation of an oblate K isomer in a deformed nucleus. This opens up the possibility for a new region of K isomers at low Z and at oblate deformation, involving the same neutron orbitals as the prolate orbitals within the classic Z∼72 deformed hafnium region. From an interpretation of the level scheme guided by theoretical calculations, an oblate deformation is also suggested for the ^{94}Se_{60} ground-state band.

Published
2020

48. Spectroscopy of short-lived radioactive molecules

Author

Alex Brinson, Mark Bissell, A. R. Vernon, R. F. Garcia Ruiz, B. S. Cooper, K. Chrysalidis, Gerda Neyens, Klaus Wendt, R. Â. P. de Groote, Shane Wilkins, J. Billowes, Xiaofei Yang, Robert Berger, Á. Koszorús, C. L. Binnersley, Frank Wienholtz, T. A. Isaev, Lutz Schweikhard, Thomas Elias Cocolios, Thomas F. Giesen, Alexander A. Breier, S. Franchoo, C. M. Ricketts, Fredrik Gustafsson, H. A. Perrett, Kieran Flanagan, Sebastian Rothe, Institut de Physique Nucléaire d'Orsay (IPNO), 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
spektroskopia, collinear, nucl-ex, 01 natural sciences, 010305 fluids & plasmas, Radium, chemistry.chemical_compound, Ionization, Experimental nuclear physics, Nuclear Experiment, Physics, Multidisciplinary, Large Hadron Collider, Stable isotope ratio, new physics, [PHYS.HTHE]Physics [physics]/High Energy Physics - Theory [hep-th], hep-th, molekyylit, hep-ph, radium, electron: electric moment, Nuclear Physics - Theory, radioactivity, many-body problem, Electronic structure of atoms and molecules, Atomic physics, ydinfysiikka, Particle Physics - Theory, exceptional, nucl-th, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], Monofluoride, ResearchInstitutes_Networks_Beacons/photon_science_institute, chemistry.chemical_element, nucleus: structure function, Electronic structure, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Photon Science Institute, Article, 0103 physical sciences, ionization, Molecule, Nuclear Physics - Experiment, 010306 general physics, Spectroscopy, enhancement, Particle Physics - Phenomenology, stability, sensitivity, laser, chemistry, [PHYS.HPHE]Physics [physics]/High Energy Physics - Phenomenology [hep-ph], Exotic atoms and molecules, nucleus: deformation
Abstract

Molecular spectroscopy offers opportunities for the exploration of the fundamental laws of nature and the search for new particle physics beyond the standard model1–4. Radioactive molecules—in which one or more of the atoms possesses a radioactive nucleus—can contain heavy and deformed nuclei, offering high sensitivity for investigating parity- and time-reversal-violation effects5,6. Radium monofluoride, RaF, is of particular interest because it is predicted to have an electronic structure appropriate for laser cooling6, thus paving the way for its use in high-precision spectroscopic studies. Furthermore, the effects of symmetry-violating nuclear moments are strongly enhanced5,7–9 in molecules containing octupole-deformed radium isotopes10,11. However, the study of RaF has been impeded by the lack of stable isotopes of radium. Here we present an experimental approach to studying short-lived radioactive molecules, which allows us to measure molecules with lifetimes of just tens of milliseconds. Energetically low-lying electronic states were measured for different isotopically pure RaF molecules using collinear resonance ionisation at the ISOLDE ion-beam facility at CERN. Our results provide evidence of the existence of a suitable laser-cooling scheme for these molecules and represent a key step towards high-precision studies in these systems. Our findings will enable further studies of short-lived radioactive molecules for fundamental physics research., Measurements of low-energy electronic states of radium monofluoride validate predictions of the use of this short-lived radioactive molecule in exploring fundamental physics and provide evidence of its suitability for laser cooling.

Published
2020

49. Metastable States of ^{92,94}Se: Identification of an Oblate K Isomer of ^{94}Se and the Ground-State Shape Transition between N=58 and 60

Author

C, Lizarazo, P-A, Söderström, V, Werner, N, Pietralla, P M, Walker, G X, Dong, F R, Xu, T R, Rodríguez, F, Browne, P, Doornenbal, S, Nishimura, C R, Niţă, A, Obertelli, T, Ando, T, Arici, G, Authelet, H, Baba, A, Blazhev, A M, Bruce, D, Calvet, R J, Caroll, F, Château, S, Chen, L X, Chung, A, Corsi, M L, Cortés, A, Delbart, M, Dewald, B, Ding, F, Flavigny, S, Franchoo, J, Gerl, J-M, Gheller, A, Giganon, A, Gillibert, M, Górska, A, Gottardo, I, Kojouharov, N, Kurz, V, Lapoux, J, Lee, M, Lettmann, B D, Linh, J J, Liu, Z, Liu, S, Momiyama, K, Moschner, T, Motobayashi, S, Nagamine, N, Nakatsuka, M, Niikura, C, Nobs, L, Olivier, Z, Patel, N, Paul, Zs, Podolyák, J-Y, Roussé, M, Rudigier, T Y, Saito, H, Sakurai, C, Santamaria, H, Schaffner, C, Shand, I, Stefan, D, Steppenbeck, R, Taniuchi, T, Uesaka, V, Vaquero, K, Wimmer, and Z, Xu

Abstract

Here we present new information on the shape evolution of the very neutron-rich ^{92,94}Se nuclei from an isomer-decay spectroscopy experiment at the Radioactive Isotope Beam Factory at RIKEN. High-resolution germanium detectors were used to identify delayed γ rays emitted following the decay of their isomers. New transitions are reported extending the previously known level schemes. The isomeric levels are interpreted as originating from high-K quasineutron states with an oblate deformation of β∼0.25, with the high-K state in ^{94}Se being metastable and K hindered. Following this, ^{94}Se is the lowest-mass neutron-rich nucleus known to date with such a substantial K hindrance. Furthermore, it is the first observation of an oblate K isomer in a deformed nucleus. This opens up the possibility for a new region of K isomers at low Z and at oblate deformation, involving the same neutron orbitals as the prolate orbitals within the classic Z∼72 deformed hafnium region. From an interpretation of the level scheme guided by theoretical calculations, an oblate deformation is also suggested for the ^{94}Se_{60} ground-state band.

Published
2020

50. Shell structure of the neutron-rich isotopes Co69,71,73

Author

M. Lettmann, A. Gillibert, Alessandra Corsi, David Steppenbeck, S. Leblond, Yoshiaki Shiga, K. Yoshida, Toshiyuki Sumikama, Ryo Taniuchi, A. Gottardo, F. Nowacki, Jenny Lee, V. Lapoux, Yuya Kubota, C. Péron, A. Delbart, Shunji Nishimura, G. Authelet, Si-Ge Chen, P. A. Söderström, C. Louchart, J. M. Gheller, T. Miyazaki, Alan Peyaud, C. M. Shand, Satoshi Takeuchi, Masafumi Matsushita, F. Giacoppo, H. Baba, Satoru Momiyama, S. Franchoo, E. Sahin, Zhenci Xu, Jinguang Wu, Shuichi Ota, V. Werner, Hideaki Otsu, Alfredo Poves, L. X. Chung, Megumi Niikura, C. Santamaria, Tomohiro Uesaka, I. Stefan, K. Matsui, P. Doornenbal, Kazuyuki Ogata, F. Browne, Masaki Sasano, Zs. Dombrádi, Shoko Koyama, Z. Korkulu, Zs. Vajta, K. Hadynska-Klek, T. Lokotko, Z. Patel, L. Olivier, H. Wang, R. Lozeva, A. Obertelli, Hiroyoshi Sakurai, T. Motobayashi, E. C. Pollacco, J.-Y. Roussé, D. Calvet, T. Isobe, F. Château, and Daisuke Suzuki

Subjects
Physics, Isotope, 010308 nuclear & particles physics, Nuclear structure, Impulse (physics), 7. Clean energy, 01 natural sciences, Coincidence, Nuclear physics, MINOS, 0103 physical sciences, Neutron, Detector array, Nuclear Experiment, 010306 general physics, Excitation
Abstract

The structures of the neutron-rich Co69,71,73 isotopes were investigated via (p,2p) knockout reactions at the Radioactive Isotope Beam Factory, RIKEN. Isotopes of interest were studied using the DALI2 γ-ray detector array combined with the MINOS target and tracker system. Level schemes were reconstructed using the γ-γ coincidence technique, with tentative spin-parity assignments based on the measured inclusive and exclusive cross sections. Comparison with shell-model calculations using the Lenzi-Nowacki-Poves-Sieja LNPS and PFSDG-U interactions suggests coexistence of spherical and deformed shapes at low excitation energies in the Co69,71,73 isotopes. The distorted-wave impulse approximation (DWIA) framework was used to calculate the single-particle cross sections. These values were compared with the experimental findings.

Published
2020

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