Yazar "Costache, C." seçeneğine göre listele

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  • [ X ]
    Öğe
    Band structures, lifetimes, and shape coexistence in 130La
    (Amer Physical Soc, 2020) Ionescu-Bujor, M.; Aydin, S.; Iordachescu, A.; Marginean, N.; Pascu, S.; Bucurescu, D.; Costache, C.
    The level structure of La-130 has been investigated using the (121)sb(C-12, 3n) reaction with the ROSPHERE array at IFIN-HH, Bucharest. The level scheme was significantly extended with the observation of 45 new states and 100 new transitions. Several band structures have been identified and a clear connection with the lower-lying states has been established. A lifetime of tau = 3.6(2) ns has been measured for the 346-keV 6(-) state by the in-beam fast timing technique. The lifetimes of 18 high-spin states have been determined by applying the Doppler-shift attenuation method. The deformations derived from the experimental B(E2) transition strengths indicate distinct coexisting shapes at high spins in La-130. The experimental properties of both low- and high-spin states were compared with theoretical calculations performed in the frame of the two-quasiparticles-plus-rotor model. Two new negative-parity decoupled bands, with a deduced quadrupole deformation beta(2) = 0.150(15), were interpreted by coupling the proton in the 1/2[550] and 3/2[541] orbitals with the odd neutron occupying mainly the low-Omega orbitals from the d(3/2) and 5(1/2) states. A quadrupole deformation beta(2) = 0.220(17) was derived for a newly identified positive-parity decoupled band. This enhanced deformation was attributed to the involvement in the band configuration of the Omega = 1/2 (f(7/2), h(9/2)) intruder neutron orbital. The multiparticle configuration pi g(7/2)(h(11/2))(2) circle times nu (h(11/2)) was assigned to a high-spin negative-parity dipole band, based on the comparison of the experimental B(M1) transition strengths with values calculated by applying the geometrical model of Donau and Frauendorf.
  • [ X ]
    Öğe
    Lifetime measurements and evidence for triaxial nuclear shapes in 127Cs
    (Amer Physical Soc, 2021) Aydin, S.; Ionescu-Bujor, M.; Marginean, N.; Costache, C.; Bucurescu, D.; Florea, N.; Glodariu, T.
    Rotational bands built on single quasiproton excitations in Cs-127 have been investigated using the Sb-121(C-12, alpha 2n) reaction and the ROSPHERE detector array at IFIN-HH, Bucharest. The lifetimes in the yrast negative-parity band based on the proton in h11/2 orbital have been measured by applying the Doppler-shift attenuation method. The lifetime of the 7/2+ 273-keV state, member of the rotational band associated with the proton g(7/2) orbital, has been determined as tau = 1.22(5) ns by the fast timing technique. The experimental data were compared with the calculations performed using the quasiparticle plus triaxial rotor model and deformation parameters epsilon(2) and gamma have been derived for the positive-and negative-parity structures. Evidence for triaxial nuclear shapes in the states described by the proton h(11/2) orbital was provided by both signature splitting and B(E2, Delta J = 2) transition strengths.