Large scale shell model calculations for odd-odd 58−62^{58-62}Mn isotopes

Large scale shell model calculations have been carried out for odd-odd $^{58-62}$Mn isotopes in two different model spaces. First set of calculations have been carried out in full $\it{fp}$ shell valence space with two recently derived $\it{fp}$ shell interactions namely GXPF1A and KB3G treating $^{40}$Ca as core. The second set of calculations have been performed in ${fpg_{9/2}}$ valence space with the $fpg$ interaction treating $^{48}$Ca as core and imposing a truncation by allowing up to a total of six particle excitations from the 0f$_{7/2}$ orbital to the upper $\it{fp}$ orbitals for protons and from the upper $\it{fp}$ orbitals to the 0g$_{9/2}$ orbital for neutron. For low-lying states in $^{58}$Mn, the KB3G and GXPF1A both predicts good results and for $^{60}$Mn, KB3G is much better than GXPF1A. For negative parity and high-spin positive parity states in both isotopes $fpg$ interaction is required. Experimental data on $^{62}$Mn is sparse and therefore it is not possible to make any definite conclusions. More experimental data on negative parity states is needed to ascertain the importance of 0g$_{9/2}$ and higher orbitals in neutron rich Mn isotopes.Comment: 5 pages, 4 figures, Submitted to Eur. Phys. J.

Gd-149:What's confirmed? What's new?

A long run performed with EUROGAM II allowed remeasuring the Gd-149 superdeformed (SD) band 1. The Delta I = 4 bifurcation in band 1 is confirmed and two resolved gamma-ray transitions linking the SD band 1 and the normal deformed states have been observed

Gd-149:What's confirmed? What's new?

A long run performed with EUROGAM II allowed remeasuring the Gd-149 superdeformed (SD) band 1. The Delta I = 4 bifurcation in band 1 is confirmed and two resolved gamma-ray transitions linking the SD band 1 and the normal deformed states have been observed

Extended investigation of superdeformed bands in 151,152^{151,152}Tb nuclei

A detailed study of known and new SD bands in Tb isotopes has been performed with the use of the EUROBALL IV -ray array. The high-statistics data set has allowed for the extension of known SD bands at low and high spins by new -ray transitions. These transitions, as it turns out, correspond to the rotational frequencies where the principal superdeformed gaps (Z=66,N=86) close giving rise to up- or down-bending mechanisms. This enables to attribute the underlying theoretical configurations with much higher confidence as compared to the previous identifications. Five new SD bands have been discovered, three of them assigned to the 152Tb and the two others to the 151Tb nuclei. Nuclear mean-field calculations have been used to interpret the structure of known SD bands as well as of the new ones in terms of nucleonic configurations

Deexcitation of superdeformed bands in the nucleus Tb-151

The aim of this work is to get more informations about the decay-out of superdeformed bands. One of the best candidates in the mass A similar or equal to 150 region for that kind of research is the nucleus Tb-151. From previous works, it has been established that the first excited band goes lower in frequency than the band SD(1) [2], and it is the only known case in that mass region. One way to investigate these different behaviours, is to perform measurements of the average entry spin. The nucleus Tb-151 has been populated via the fusion-evaporation reaction Te-130(Al-27,6n)Tb-151 at a beam energy of 155 MeV. This experiment has been performed at the Vivitron facility accelerator in Strasbourg using the Eurogam II spectrometer, consisting of 54 Germa nium detectors. It came out of this study, that the band SD(2) and band SD(3) feed the normal deformed well 9HBAR lower than the band SD(1). For the moment, it is not possible to explain the observed shell structure effects and to conclude about the statistical decay-out. The analysis is still under progress

Fast Rotation of the N=Z Nucleus 36Ar

A highly-deformed rotational band has been identified in the N=Z nucleus 36Ar. At high spin the band is observed to its presumed termination at I=16+, while at low spin it has been firmly linked to previously known states in 36Ar. Spins, parities, and absolute excitation energies have thus been determined throughout the band. Lifetime measurements establish a large low-spin quadrupole deformation (beta_2=0.46+-0.03) and indicate a decreasing collectivity as the band termination is approached. With effectively complete spectroscopic information and a valence space large enough for significant collectivity to develop, yet small enough to be meaningfully approached from the shell model perspective, this rotational band in 36Ar provides many exciting opportunities to test and compare complementary models of collective motion in nuclei