Effective moment of inertia in132Ce,134Nd and136Nd

The effective moment of inertiaI _eff ⁽²⁾ of¹³²Ce,¹³⁴Nd and¹³⁶Nd produced in⁴⁰Ar induced reactions has been deduced from continuumγ-ray spectra measured by sum spectrometer methods. Results concerning the deformation of these nuclei are obtained by comparison of the experimental data and calculations in the frame of a cranking Nilsson — Strutinsky model.     

124Sn target residues in the interaction of heavy ions at intermediate energies

Cross sections, recoil energy distributions for residues produced by¹⁴N,²⁰Ne,⁴⁰Ar on¹²⁴Sn targets have been measured in the 10–70 MeV/u intermediate energy range. As the projectile energy increases, processes as complete fusion-evaporation, incomplete fusion-evaporation and intranuclear cascade-evaporation participate progressively in the nuclear collisions. Peculiar residues corresponding to a gain of 4, 5 or even 6 protons for the¹²⁴Sn target have been observed in the 30–50 MeV energy range.     

New investigation of the decay of the high-spin isomer in 151Er

The decay of the T _1/2 = 420 ns isomer in ¹⁵¹Er has been reinvestigated. The multipolarities of the decaying transitions have been established by measuring the electron conversion coefficients. An I ^π = 67/2⁻ assignment is proposed for this isomer with a π[h ₁₁^2/4 d ₃^2/1 d ₅^2/−1]⊗ν[f _7/2 h _9/2 h ₁₁^2/−1] configuration.     

Influence of the mass asymmetry of the entrance channel on incomplete fusion processes

The angular and velocity distributions of incomplete fusion residues have been measured, around 30 AMeV projectile incident energy, for a number of systems with varying mass asymmetries, from the most asymmetric S+Cu, to the almost symmetric Ar+Ca. The main experimental finding is that the parallel width of the velocity distribution increases sharply for decreasing asymmetries, while the perpendicular width remains nearly constant. Using, as data, the widths and mean values of the velocity distributions, it was possible to derive the number of preequilibrium particles emitted by the projectile and by the target. It was found that target emission becomes noticeable only when the center of mass velocity of the target, at nuclear contact, exceeds approximately 2.5 cm/ns. This underlines the relevance of the center of mass velocities in the preequilibrium emission and incomplete fusion processes.     

Observation of band structures in the odd-odd nucleus126La

The odd-odd nucleus¹²⁶La has been studied in the reactions¹¹¹Cd(¹⁹F,4n) and⁹³Nb(³⁷Cl,p3n). Three band structures have been identified, two of them having both signature members and ΔI=1 character. These are proposed, respectively, to have πh_11/2 ? νh_11/2 and πh_11/2 ? νg_7/2 configurations and tentative 4⁺ and 3^? band heads.     

Band terminations in valence-space and core-excited configurations in102Pd

The level structure of¹⁰²Pd has been investigated using the Eurogam Phase2 array. Termination of rotational bands has been observed atI=28^? andI=32⁺, and tentatively atI=38⁺ andI=42⁺. Three other bands evolving towards termination have also been identified. These terminating bands are explained in terms of valence-space and core-excited configurations.     

Decay of 129Ce to low-lying positive-parity states in 129La

Low-lying levels of the ¹²⁹La isotope have been investigated through the β⁺/EC decay of ¹²⁹Ce. The radioactive nuclei were produced in the ⁹⁴Mo+⁴⁰Ca reaction at a bombarding energy of 255 MeV and transported with a He-jet system. On-line mass separation was used to select the ¹²⁹Ce beta-decay γ-γ-t, X- γ- t, e^?-γ -t coincidence measurements as well as time multi-analysis were performed. Internal conversion electrons were recorded with a magnetic selector and multipolarities deduced. The level scheme of ¹²⁹La is discussed and compared with the calculations made in the frame of the neutron-proton Interacting Boson-Fermion Model (IBFM-2).     

Decay of127Ce to low-lying states in127La

The high-spin states of¹⁹⁸Bi have been studied in the reaction¹⁸⁷Re(¹⁶O, 5n)¹⁹⁸Bi at¹⁶O energies from 85 to 105 MeV. In-beam measurements of γ-ray excitation functions, γ-γ-t coincidences and γ-ray angular distributions were carried out with six BGO(AC)HPGe detectors and one intrinsic Ge planar detector. A level scheme for¹⁹⁸Bi- with 26 γ rays was established for the first time, including a 15⁺ isomer with a measured half-life of 8.0±3.6 ns.     

In-band M1 and E2 transition rates and collective structures in Ba

Subpicosecond mean lifetimes of eight excited states in ¹²⁸Ba populated via the ⁹⁶Zr(³⁶S,4n) reaction were measured by the Doppler-shift attenuation (DSA) technique using a line-shape analysis. The differential decay-curve method (DDCM) was applied for the lifetime determination. The B(E2) values in the yrast band indicate that the first band-crossing is with a proton S-band. The configuration πh_11/2d_5/2 of the negative-parity semi-decoupled bands is confirmed by the measured B(E2, I → I − 2) and B(M1, I → I − 1) transition strengths. The higher-lying “dipole” band in ¹²⁸Ba can be described as a high-K four-quasiparticle band built on the prolate configuration (πh_11/2d_5/2) (νh_11/2g_7/2).