[en] An update on the analysis of the EXILL and FATIMA data on ¹⁴⁸Ce will be given. ¹⁴⁸Ce lies on the down boundaries of a shape phase transition region of the even-even N=90 isotones with Z=60-66. The B_4/2 value will point out the behaviour of the phase transition evolution. A first estimation is presented, and it is connected to a new CPS called X(4). ²³⁵U and ²⁴¹Pu fission fragments were measured by a mixed spectrometer consisting of Ge and LaBr₃(Ce)-scintillator detectors at the ILL. Lifetimes in the ps region are extracted with the slope and the General Centroid Difference method. This kind of analysis can serve as preparation for the FATIMA experiments at FAIR.

[en] Short communication. 4 refs. 1 tab

[en] Short communication. 4 refs., 2 tabs

[en] High spin states in 136,137La and 148Ce nuclei have been investigated. The new level schemes for these nuclei have been established. In 136La, observed band crossing as well as the signature splitting and inversion in πh11/2(multiply-in-circle sign)νh11/2 band has been discussed. Other two bands were proposed as oblate deformation with γ ∼ -60 deg. In 137La, several new bands have been established. The band crossing and oblate deformation have been discussed. In 148Ce, the double octupole deformation bands with s = +1 and s = -1 have been proposed

[en] The even-even N=90 isotones with Z=60-66, present an interesting phase transition. This phase transition in nuclei is characterized by a sudden change of the shape of the nucleus. ¹⁴⁸Ce lies on the down-boundaries of the phase transition region and therefore further elucidate the underlying mechanisms that lend the shape phase transition behavior. ²³⁵U and ²⁴¹Pu fission fragments were measured by a mixed spectrometer consisting of high resolution Ge and fast LaBr₃(Ce)-scintillator detectors at the high-flux reactor of the ILL. Prompt γ-ray cascades from the nuclei of interest are selected via Ge-Ge-LaBr₃-LaBr₃ coincidences. The good energy resolution of the Ge allows precise gates to be set, selecting the cascade, hence, the nucleus of interest. The excellent timing performance of the LaBr₃ detectors in combination with the General Centroid Difference method allows the measurement of lifetimes in the ps range in preparation for the FATIMA experiment at FAIR. The first results on neutron-rich ¹⁴⁸Ce are presented: τ(4+)=49 (7) ps and τ(2⁺)=1417 (41) ps and B(4/2)=(1.73±0.28). This document is composed of an abstract and the slides of the presentation.

No abstract available

[en] From γ-γ-γ and γ-γ-γ-γ coincidence studies of spontaneous fission of ²⁵²Cf, new high spin states in ¹⁴⁸Ce were identified. The octupole bands with $\mathrm{s}=+1$ and $\mathrm{s}=-1$ are expanded with spins with 28⁺ and 18⁻, respectively. Importantly, a 1γ vibrational band has been established up to 14⁺ and a 1β vibrational band up to 6⁺. The levels in γ and β bands in ¹⁴⁸Ce are compared systematically to those in neighboring ¹⁵⁰Nd and ¹⁵²Sm isotones. This comparison informs the role of deformation and shape transition in this mass region. New 3⁻ and 5⁻ members of the $\mathrm{s}=+1$ octupole band were observed.

[en] The decay of ¹⁴⁸Ce to levels of ¹⁴⁸Pr has been studied using mass-separated sources. A half-life of 56 +- 1 s has been measured for the decay of ¹⁴⁸Ce. A level scheme containing 40 γ rays and 15 excited levels is proposed for ¹⁴⁸Pr. Strongly β-fed 1⁺ levels have been identified at 390 and 520 keV that are similar in position to 1⁺ levels observed in isotonic ¹⁴⁶La and isotopic ¹⁴⁶Pr

[en] Neutron rich nuclei lying in the vicinity of doubly magic core ¹³²Sn are becoming one of the interesting research areas to study the nuclear structure. One such example is Cerium. The neutron rich isotopes of cerium provide information about the transition region from spherical to deformed nuclei. From earlier studies it has been observed that in cerium isotopes the nuclear deformation begins to occur between N = 86 and N = 88. Also, the shape transition in the even Ce isotopes from being spherical nuclei to deformed has been observed. The Skyrme-Hartree-Fock and Bardeen-Cooper-Schrieffer (BCS) approaches (microscopic), and an algebraic collective model (macroscopic approach) were recently used to investigate cerium isotopes, which suggested that the phase transition from spherical to deformed occurs between ¹⁴⁶Ce and ¹⁴⁸Ce. It has also been found that ¹⁴²Ce with two valence neutrons exhibits a vibrational spectrum, but with the addition of more neutrons, ¹⁴⁸Ce begins to exhibit rotational behavior. The yrast band and the backbending plots are obtained using the TPSM technique for the even-even ^144-148Ce isotopes. The results are compared with the available experimental data and it has been observed that they are in agreement with each other

[en] Recently, Gupta and Hamilton have pointed out that the absolute slopes of the kinetic MoI versus spin I, using expression, represents only the deformation of the core, not the change in nuclear structure with spin. This is important, especially for near spherical nuclei. Instead, it is the change in slope with spin I, which represents the variation of nuclear structure with spin. Here we illustrate this aspect of nuclear structure by looking at the correspondence of the variation of kinetic MoI with spin and the value of 'b' in the power index formula