Yazar "Bocchi, Giovanni" seçeneğine göre listele

Listeleniyor 1 - 2 / 2
  • [ X ]
    Öğe
    Multifaceted Quadruplet of Low-Lying Spin-Zero States in Ni 66: Emergence of Shape Isomerism in Light Nuclei
    (American Physical Society, 2017) Leoni, Silvia; Fornal, Bogdan; Mârginean, Nicolae Marius.; Sferrazza, Michele; Tsunoda, Yuhsuke; Otsuka, Takaharu; Bocchi, Giovanni; Aydın, Sezgin
    A search for shape isomers in the Ni66 nucleus was performed, following old suggestions of various mean-field models and recent ones, based on state-of-the-art Monte Carlo shell model (MCSM), all considering Ni66 as the lightest nuclear system with shape isomerism. By employing the two-neutron transfer reaction induced by an O18 beam on a Ni64 target, at the sub-Coulomb barrier energy of 39 MeV, all three lowest-excited 0+ states in Ni66 were populated and their ? decay was observed by ?-coincidence technique. The 0+ states lifetimes were assessed with the plunger method, yielding for the 02+, 03+, and 04+ decay to the 21+ state the B(E2) values of 4.3, 0.1, and 0.2 Weisskopf units (W.u.), respectively. MCSM calculations correctly predict the existence of all three excited 0+ states, pointing to the oblate, spherical, and prolate nature of the consecutive excitations. In addition, they account for the hindrance of the E2 decay from the prolate 04+ to the spherical 21+ state, although overestimating its value. This result makes Ni66 a unique nuclear system, apart from U236,238, in which a retarded ? transition from a 0+ deformed state to a spherical configuration is observed, resembling a shape-isomerlike behavior. © 2017 American Physical Society.
  • [ X ]
    Öğe
    Probing particle-phonon-coupled states in the neutron-rich nucleus Cu 65 by lifetime measurements with fast-timing techniques
    (American Physical Society, 2014) Bocchi, Giovanni; Leoni, Silvia; Bottoni, Simone; Benzoni, Giovanna; Bracco, Angela; Bortignon, Pier Francesco; Colò, Gianluca; Aydın, Sezgin
    The Cu65 nucleus was populated by the Ni64(Li7,?2n)Cu65 reaction and the lifetime of the 9/2+ state at 2.5 MeV was measured by electronic fast-timing technique, providing the value ?= 37(3) ps. The reduced transition probability B(E3)=8.82(165) W.u. is deduced and compared to theoretical predictions in the framework of a particle-vibration (weak) coupling model. The results indicate that the 9/2+ state is a member of the 3- - ?p3/2 multiplet, built by coupling the octupole 3- phonon of Ni64 to an unpaired proton in the p3/2 level, confirming the robustness of core excitations in the medium mass nucleus Ni64. © 2014 American Physical Society.