Paul, N.*; Obertelli, A.*; Bertulani, C. A.*; Corsi, A.*; Doornenbal, P.*; Rodriguez-Sanchez, J. L.*; Authelet, G.*; Orlandi, R.; 他84名*
Physical Review Letters, 122(16), p.162503_1 - 162503_7, 2019/04
Fifty-five single nucleon removal cross sections from neutron-rich nuclei impinging on a hydrogen target at about 250 MeV/nucleon were measured at the RIKEN RIBF. Systematically higher cross sections are found for proton removal from nuclei with an even number of protons compared to odd-proton number projectiles for the same separation energy, while no even-odd staggering was observed in case of neutron-removal. These observations are linked to paring correlations in the daughter nuclei and the density of bound levels. The effect is particularly strong in loosely bound nuclei.
Elekes, Z.*; Kripk, *; Sohler, D.*; Sieja, K.*; 緒方 一介*; 吉田 数貴; Doornenbal, P.*; Obertelli, A.*; Authelet, G.*; 馬場 秀忠*; et al.
Physical Review C, 99(1), p.014312_1 - 014312_7, 2019/01
(,)反応によるNiの核構造の探索実験を行った。Lenzi, Nowacki, Poves, Sieja相互作用を用いた殻模型計算では実験結果を説明しうる陽子空孔状態が得られており、理論的な断面積計算は実験値とよい一致を与えた。実験で得られたすべての状態を理論的に一意に決定することはできなかったが、過去の実験結果と同様にNi同位体でのZ = 28の大きなshell gapを示す結果が得られた。
Shand, C. M.*; Podolyk, Zs.*; Grska, M.*; Doornenbal, P.*; Obertelli, A.*; Nowacki, F.*; Otsuka, T.*; Sieja, K.*; Tostevin, J. A.*; Tsunoda, T.*; et al.
Physics Letters B, 773, p.492 - 497, 2017/10
Low-lying states in neutron-rich Zn nuclei were measured for the first time via in-beam -ray spectroscopy at RIKEN. These include the 4 to 2 in Zn and the 2 to 0 and 4 to 2 in Zn. The reduced E() energies and increased E(4)/E(2) ratios at =52,54 compared to Zn attest that the magicity is confined just on the neutron number =50 only. The levels observed in Zn suggest the onset of deformation towards heavier Zn isotopes. The data were compared to state-of-the-art shell model calculations.
Flavigny, F.*; Doornenbal, P.*; Obertelli, A.*; Delaroche, J.-P.*; Girod, M.*; Libert, J.*; Rodriguez, T. R.*; Authelet, G.*; Baba, H.*; Calvet, D.*; et al.
Physical Review Letters, 118(24), p.242501_1 - 242501_6, 2017/06
The first -ray spectroscopy of very neutron rich Kr isotopes was carried out at the RIBF at RIKEN Nishina center. Excited states in these isotopes were populated via (p,2p) reactions using radioactive Rb beams accelerated to 220 MeV/nucleon. The new data show a significant increase in deformation beyond N=60, as well as competing configurations (shape-coexistence) at low energy. The data were compared with beyond-mean-field calculations which predict level energies in good agreement with observation, and suggest oblate-prolate shape coexistence.
Chen, S.*; Doornenbal, P.*; Obertelli, A.*; Rodriguez, T. R.*; Authelet, G.*; Baba, H.*; Calvet, D.*; Chteau, F.*; Corsi, A.*; Delbart, A.*; et al.
Physical Review C, 95(4), p.041302_1 - 041302_6, 2017/04
Neutron-rich isotopes of selenium, Se, where studied via in beam -ray spectroscopy after nucleon removal reactions at RIBF in RIKEN. The low-energy excitations of these nuclei were investigated using - coincidences, and the first and second excited 2 states were found at remarkably low energies. The analysis and comparison with self-consistent beyond-mean field calculations suggest that both shape coexistence and triaxiality are needed to describe these isotopes.
Paul, N.*; Corsi, A.*; Obertelli, A.*; Doornenbal, P.*; Authelet, G.*; Baba, H.*; Bally, B.*; Bender, M.*; Calvet, D.*; Chteau, F.*; et al.
Physical Review Letters, 118(3), p.032501_1 - 032501_7, 2017/01
The first measurement of rays emitted by the very neutron rich nuclei Mo (Z=42) and Zr (Z=40) was carried out at the RIBF facility at RIKEN. These data shine light on the postulated N=70 harmonic oscillator shell. If the spin-orbit splitting which gives rise to the N=82 shell gap is reduced in very neutron-rich nuclei, the harmonic oscillator gap at N=70 should open instead. However, both the measured energy of the first excited state Mo and Zr, respectively 235(7) keV and 185(11) keV, and their E(4)/E(2) ratio, indicate that these nuclei are good rotors, and exclude the shell stabilization scenario at Z=40 and N=70. These results were compared to state-of-the-art density functional theoretical calculations using Gogny and Skyrme effective interactions.