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In this paper we present theoretical results on the dipole response in the proton spin-saturated Zr isotopes. The electric and magnetic dipole excitations are obtained in Hartree-Fock-Bogolyubov plus Quasi-particle Random Phase Approximation (QRPA) calculations performed with the D1M Gogny force. A pnQRPA charge exchange code is used to study the Gamow-Teller response. The results on the pygmy, the giant dipole resonances as well as those on the magnetic nuclear spin-flip excitation and the Gamow-Teller transitions are compared with available experimental or theoretical information. In our approach, the proton pairing plays a role in the phonon excitations, in particular in the M1 nuclear spin-flip resonance. [ABSTRACT FROM AUTHOR]

A fast-timing setup has been developed to measure the nuclear-state half-lives of neutron-rich nuclei. The first on-line measurements were performed on Cs obtained from the β decay of Xe. These neutron-rich Xe nuclei were produced by the U photofission induced by the 50MeV electron beam delivered by the ALTO facility. The half-lives of the first excited state in Cs and of six excited states in Cs were measured for the first time. Taking into account new information given by the deduced transition probabilities, we discuss the structure of the first excited states in Cs : it is shown that, in both nuclei, the first excited $$\tfrac{5} {2}^ +$$ level corresponds mainly to the one-proton state issued from the π2 d orbital and that the most probable spin values for the states located at 289.8, 393.5, and 393.8keV in Cs are $$\tfrac{5} {2}^ +$$, $$\tfrac{3} {2}^ +$$, and $$\tfrac{1} {2}^ +$$, respectively. [ABSTRACT FROM AUTHOR]

Odd-odd 136Cs nuclei have been produced in the 18O + 208Pb and 12C + 238U fusion-fission reactions and their γ rays studied with the Euroball array. The high-spin level scheme was built up to ~4.7 MeV excitation energy and spin I ~ 16h from the triple γ-ray coincidence data. The configurations of the three structures observed above ~2 MeV excitation energy are first discussed bγ analogy with the proton excitations identified in the semimagic 137Cs82 nucleus, which involve the three high-j orbits lying above the Z = 50 gap, πg7/2, πd5/2, and πhn1/2- This is confirmed by the results of shell-model calculations performed in this work. [ABSTRACT FROM AUTHOR]

Abstract: Nine lifetimes have been determined for the first time in the and bands of 167Yb by means of Recoil distance Doppler-shift measurements carried out at the Cologne FN tandem. For the data analysis, a dedicated version of the Differential decay curve method was used. The newly deduced transition strengths and the level scheme are reasonably described by the Particle plus triaxial rotor model (PTRM) calculations except for the behavior of the quadrupole collectivity in the two signatures of the band. The stretched B(E2)ʼs in the favored signature are appreciably larger than those in the unfavored signature. The effect increases with spin. In the PTRM calculations, the wave functions of the favored signature levels contain larger contribution of low-Ω orbitals from parentage than those of the unfavored levels. This could selectively increase the deformation of the favored signature band members. If so, rotation and Coriolis interaction would give rise to a dynamic shape coexistence taking place between the two signatures. [Copyright &y& Elsevier]

Excited states up to Jπ = 11- at 10 296 keV and Jπ = 10+ at 10 707 keV have been populated in the odd-odd 36C1 nucleus using the 24Mg(14N,2p) fusion-evaporation reaction at Elab = 31 MeV. Twenty new states and 62 new γ transitions have been identified by employing γ-γ and γ-γ-γ coincidences. Lifetimes have been investigated by the Doppler shift attenuation method. The experimental data have been compared with the results of large-scale shell-model calculations performed using different effective interactions and model spaces allowing particle-hole excitations across the N = Z = 20 shell gap. [ABSTRACT FROM AUTHOR]

Five N = 82 isotones have been produced in two fusion-fission reactions and their &ggr; rays studied with the Euroball array. The high-spin states of 139La have been identified, while the high-spin yrast and near-to-yrast structures of the four others have been greatly extended. From angular correlation analysis, spin values have been assigned to some states of 136Xe and 137Cs. Several cascades involving &ggr; rays of 139La have been found to be delayed; they deexcite an isomeric state with T1/2 = 315(35) ns located at 1800 keV excitation energy. The excited states of these five N = 82 isotones are expected to be due to various proton excitations involving the three high-j subshells located above the Z = 50 shell closure. This is confirmed by the results of shell-model calculations performed in this work. In addition, high-spin states corresponding to the excitation of the neutron core have been unambiguously identified in 136Xe, 137Cs, and 138Ba. [ABSTRACT FROM AUTHOR]

The 119_126Sn nuclei have been produced as fission fragments in two reactions induced by heavy ions: 12C + 238U at a bombarding energy of 90 MeV and 18O + 208Pb at 85 MeV. Their level schemes have been built from γ rays detected using the Euroball array. High-spin states located above the long-lived isomeric states of the evenand odd-A 120-126Sn nuclei have been identified. Moreover, isomeric states lying around 4.5 MeV have been established in 120,122,124,126Sn from delayed coincidences between the fission fragment detector SAPhIR and the Euroball array. The states located above 3 MeV excitation energy are ascribed to several broken pairs of neutrons occupying the vh11/2 orbit. The maximum value of angular momentum available in such a high-j shell, i.e., for midoccupation and the breaking of the three neutron pairs, has been identified. This process is observed for the first time in spherical nuclei. [ABSTRACT FROM AUTHOR]