M. N. Rao

Shape change along the highly-deformed band in 137Nd☆

Abstract Lifetimes of states of the highly-deformed (HD) band in 137Nd have been measured using the Doppler shift attenuation method. A line-shape analysis has been carried out for individual states, resulting in transition quadrupole moments which decrease with increasing spin. This represents the first confirmation of previous total routhian surface (TRS) calculations that predicted a drift towards positive γ values of the HD minimum (at essentially constant β deformation). The lifetime data show a rather modest deformation of the HD band structure, indicating a softening of the nuclear potential at HD shape.

Study of the effect of disorder on the local magnetism in Heusler alloys

A local study of the influence of annealing temperature that can provoke structural defects and chemical disorder on the magnetism of Heusler alloys has been carried out by measuring hyperfine interactions in Pd2MnZ (Z=Ge, In, Sn, and Sb). Perturbed angular correlation method has been used to measure the hyperfine fields at Cd111 probe nuclei substituting the Mn and Z sites as a function of temperature. The fraction of In111-nuclei-occupying Mn sites was found to increase with the annealing of sample at higher temperatures followed by quenching that can leave the alloy in a disordered state. As a consequence, it was possible to observe the effect of temperature in the ordering of the alloys. Moreover, electric quadrupole interaction measurements clearly indicated chemical disorder after quenching in Pd2MnSn and an improvement in the ordering of the Pd2MnGe structure at high temperatures.

Nuclear structure in odd-odd nucleus 138 Pr

With the view of extending the systematics of odd-odd Pr nuclei toward the N=82 closed shell, high-spin states in 138Pr nucleus have been investigated with the 128Te(14N, 4nγ) reaction. Configurations and spin assignments are suggested for three of the observed band-structures.

First allowed bandcrossing in neutron deficient nucleus 141Tb

The neutron deficient 141Tb nucleus has been studied with the 92Mo (54Fe, ap) reaction at 240-MeV incident energy and the multidetector array GASP. For the yrast ph11/2 decoupled band, excited states up to 6.7 MeV and spin up to 47/2- have been observed. This band presents an upbend at rotational frequency of w = 0.38 MeV due to the alignment of h11/2 protons. The results are discussed in terms of the Cranking model.

Static electromagnetic moments and nuclear shapes in 129,131Ce

Abstract The g -factors and quadrupole moments of the 9 2 − isomeric states in 129,131 Ce have been determined by the TDPAD method. The results are g = −0.185(10) and | Q | = 1.32(13) eb for 129 Ce and g = −0.189(7) and | Q | = 0.92(10) eb for 131 Ce. Firm spin-parity assignments were made on the basis of measured moments. The experimental electromagnetic moments and the level energies in the positive- and negative-parity bands were analysed within the particle-plus-triaxial-rotor model and optimum shape parameters have been established.

In-beam gamma ray spectroscopy of 58Co

The odd-odd 58Co nucleus has been studied with the 51V(10B, p2n) reaction at 33-MeV incident energy and the g-spectrometer Saci-Perere. Excited states up to 8.0 MeV and spin up to 11+ have been observed. The results are compared to Shell Model calculations using the GXPF1 effective interaction, developed for use in the fp shell. The pf7/2-1An(p3/22f5/21) configuration was assigned to the yrast levels.

Deformation of highly deformed bands in Nd nuclei

SummaryThe quadrupole moments of highly deformed bands in134,135Nd and131Ce have been determined using the Doppler-shift attenuation method. The obtainedQ0 values show no clear dependence on the number of occupiedvi13/2 intruder orbitals. Cranked shell model calculations indicate that the charge-quadrupole moments of the highly deformed bands decrease with increasing spin. The expected increase in deformation induced by thevi13/2 orbital in the two bands of134Nd is attenuated by a rotation-induced shrinking effect driving the nucleus towards smaller deformation.

{sup 18}O+{sup 110}Pd: Measurements and realistic coupled-channel analysis in a transitional region

The inelastic, two-neutron and {alpha} transfer and quasielastic cross sections for the {sup 18}O+{sup 110}Pd system have been measured in the near barrier region (40 MeV {<=}E{sub lab}{<=}58 MeV). The experiments were performed in the Sao Paulo Pelletron laboratory. Coupled-channel analysis of the experimental data was performed using the Sao Paulo potential as a microscopic bare interaction. In the calculations, low-lying inelastic excitations, one- and two-neutron and {alpha} transfers to the target were considered as the main couplings, with no extra surface absorption. The agreement between the theoretical results and the experimental data is good. The role played by the coupled channels is very different in comparison with similar data analyses for the closed-shell region around {sup 58}Ni.

High-K band in 140Gd

High-spin states in the neutron-deficient140Gd nucleus have been studied with the 92Mo(54Fe,a2p) reaction at a beam energy of 240 MeV. The level scheme of 140Gd was considerably extended from what was previously known. In this work we concentrate on one of the 9 bands observed, which presents relatively strong M1 transitions and negligible signature splitting, and has an isomeric band-head, indicating a strongly coupled or high-K configuration. We compare this band to the Kp = 8- bands observed in N=74 isotones and propose a similar configuration assignment, but with a somewhat larger deformation.

Nuclear structure of the odd–odd nucleus58Co

The odd-odd 58 Co nucleus has been studied with the 51 V( 10 B, p2n) reaction at 33 MeV and 36 MeV incident energy using the γ-spectrometer Saci-Perere. Excited states up to 8.0 MeV and spin up to 11 + have been observed. DSAM lifetimes for 13 excited states were measured. The results are compared to shell model calculations using the GXPF1 effective interaction, developed for use in the fp shell.