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Vaquero, V.*; Jungclaus, A.*; Doornenbal, P.*; Wimmer, K.*; Gargano, A.*; Tostevin, J. A.*; Chen, S.*; Ncher, E.*; Sahin, E.*; 志賀 慶明*; et al.
Physical Review Letters, 118(20), p.202502_1 - 202502_5, 2017/05
被引用回数:18 パーセンタイル:76.52(Physics, Multidisciplinary)Excited states in Sn were populated following one-neutron knockout reaction from an unstable Sn beam at the RIBF laboratory in RIKEN. In addition to the already known rays, additional strength was observed for the first time in the excitation-energy range 3.5-5.5 MeV. Since the neutron separation energy of Sn is low, this observation provides direct evidence for the radioactive decay of neutron-unbound states in this nucleus. The ability of decay to compete with neutron emission was attributed to a mismatch between the wave functions of the initial and final states in the neutron emission case. These findings suggest that in the region south-east of Sn, nuclear structure effects play a significant role in the decay of unbound states, which are instead usually ignored in the evaluation of neutron-emission probabilities in astrophysical simulations.
Morales, A. I.*; Benzoni, G.*; Watanabe, H.*; 角田 佑介*; Otsuka, T.*; 西村 俊二*; Browne, F.*; Daido, R.*; Doornenbal, P.*; Fang, Y.*; et al.
Physics Letters B, 765, p.328 - 333, 2017/02
被引用回数:31 パーセンタイル:92.19(Astronomy & Astrophysics)The level schemes of neutron-rich isotopes Co and Ni were populated in the decay of Fe and studied using -delayed -ray spectroscopy of the decay, at the RIBF in RIKEN, Japan. The experimental results were compared to state-of-the-art shell-model calculations, and indicate a dominance of prolate deformation in the low-lying states, coexisting with spherical states. The decay of the isobars is shown to progress in accordance to a new type of shell evolution, the so-called Type II, which involves many particle-hole excitations across energy gaps.
Morales, A. I.*; Benzoni, G.*; Watanabe, H.*; 西村 俊二*; Browne, F.*; Daido, R.*; Doornenbal, P.*; Fang, Y.*; Lorusso, G.*; Patel, Z.*; et al.
Physical Review C, 93(3), p.034328_1 - 034328_14, 2016/03
被引用回数:25 パーセンタイル:85.51(Physics, Nuclear)Low-lying excited states in Ni have been investigated at RIKEN by studying the decay of Co to Ni. Co was separated with BigRIPS, implanted into the WaS3ABi Silicon array, and the ray measured using the EURICA spectrometer. From the analysis, 60 new -ray transitions and 21 new levels in Ni were observed. The new experimental information is compared to shell-model calculations which include neutron excitation across the shell. The calculations reproduce rather well the observed states, implying that a clear understanding of these low-lying excitations has been achieved.
Benzoni, G.*; Morales, A. I.*; Watanabe, H.*; 西村 俊二*; Coraggio, L.*; Itaco, N.*; Gargano, A.*; Browne, F.*; Daido, R.*; Doornenbal, P.*; et al.
Physics Letters B, 751, p.107 - 112, 2015/12
被引用回数:20 パーセンタイル:78.31(Astronomy & Astrophysics)The decays of Mn have been measured at the RIBF facility at RIKEN using the EURICA spectrometer combined with an active stopper consisting of a stack of Si detectors. Half-lives and -delayed neutron emission probabilities have been extracted for these decays, together with first experimental information on excited states populated in Fe. The data indicate a continuously increasing deformation for Fe isotopes up to A=70, and interpreted to be due to the interplay between quadrupole correlation of specific neutron orbitals and the monopole component of the proton-neutron interaction.
Sahin, E.*; Doncel, M.*; Sieja, K.*; De Angelis, G.*; Gadea, A.*; Quintana, B.*; Grgen, A.*; Modamio, V.*; Mengoni, D.*; Valiente-Dobn, J. J.*; et al.
Physical Review C, 91(3), p.034302_1 - 034302_9, 2015/03
被引用回数:25 パーセンタイル:84.57(Physics, Nuclear)The level structure of the neutron-rich Cu, Cu, and Cu isotopes was investigated using multinucleon transfer reactions at Laboratori Nazionali di Legnaro using the AGATA Demonstrator array coupled to the PRISMA magnetic spectrometer. Lifetimes of excited states in Cu nuclei were measured with the recoil-distance Doppler-shift method. The resulting electromagnetic matrix elements for transitions from excited states in Cu nuclei was used to assess the collective or single-particle character of these states. The results are compared with predictions of large-scale shell-model calculations, showing how the proton pf shell evolve as neutrons fill the 1g orbital.