N. Redon

Superdeformation and shape isomerism at zero spin

Abstract Microscopic Hartree-Fock plus BCS calculations in three-dimensional coordinate space are performed to obtain potential energy surfaces in order to analyse shape isomerism in mass regions other than the well-documented fission isomers in the actinides. Many isotopes of platinum, mercury and osmium exhibit a second minimum with a large deformation and are thus candidates for shape isomerism. The same feature also occurs around the 68 Ni nucleus. The most promising candidates for experimental verification are delineated.

Single step links of the superdeformed band in Pb-194 : A measure of the absolute excitation energy, spin and parity of the superdeformed states

Abstract The EUROGAM array has been used to investigate the decay out of the yrast superdeformed (SD) band in 194 Pb. Six single step decays from the lowest observed SD states to low-lying states at normal deformation (ND) have been identified. From this observation, the excitation energy of the SD band in 194 Pb is established at 4877 ± 1.5 keV for the 6 + SD state. The most probable spins and parities of all members of the SD band are also deduced assuming that the SD states have even spin and positive parity.

Connection of a He-jet to the medium-current source of the SARA on-line separator

Abstract The performances of a Bernas-Nier ion source coupled to a helium-jet transport system are reported. The results of coupling efficiency measurements using various cluster materials are given for a number of elements, especially of the light rare-earth region reached through heavy-ion (HI) fusion-evaporation reactions at SARA. The identification and study of several new neutron-deficient isotopes investigated using this system are presented.

Lifetimes of the superdeformed band in 192Hg

Lifetimes of states in the superdeformed band in 192Hg have been measured using the Doppler-shift attenuation and the recoil-distance methods for the high-spin and the low-spin regions, respectively. Line shapes and decay curves were obtained from high-fold γ-ray coincidence spectra measured with the EUROGAM array. The transition quadrupole moments, derived from the lifetimes, are constant with an average value of Qt = 18.6 b down to the bottom of the band where it decays to the normal states. This suggests that the superdeformed potential-energy minimum is still present at that point and that the decay proceeds by tunneling.

M1 transitions between superdeformed states in 195Tl: the fingerprint of the i132 proton intruder orbital

Abstract Dipole transitions linking the superdeformed Yrast signature-partner bands in 195Tl have been observed using the EUROGAM 1 spectrometer. From the measurements of the photon decay branching ratios, taken together with the average quadrupole moment measured in neighbouring superdeformed nuclei, we find that the two signature partner superdeformed bands involve the excitation of the 81 st proton into the i 13 2 Ω= 5 2 intruder orbital

A self-consistent study of triaxial deformations in heavy nuclei

Abstract Lattice Hartree-Fock + BCS calculations for axially asymmetrical solutions have been extended to heavy nuclei. The deformation energy surfaces in a (β, γ) sextant for the 138 Sm and 192 Os nuclei exhibit a shallow triaxial minimum, while a valley connecting smoothly the oblate and prolate minima is found in the 186 Pt nucleus.

Discovery of a new isomeric state in

We report on the observation of a new isomeric state in

^{68}

^{68}

Ni: Evidence for a highly-deformed proton intruder state.

Ni. We suggest that the newly observed state at 168(1) keV above the first 2

Observation and lifetime of the first excited superdeformed band in Hg-192

^+