High-spin states in189Hg

Abstract

High-spin levels in lS9Hg have been populated via the 175Lu(19F, 5n) reaction. A rotation-aligned band built on a 13/2 + state originating from the vi13/2 subshell is identified which is interpreted within the framework of "quasiparticle + rotor" models. A negative parity band built on a 21/2-state which can be accounted for by a three quasi-particle state is also observed.Nuclear Reactions: 17SLu(19F, 5n), E= 100 MeV; measured a(E, E.i), a(E~, 0), YYcoin, directional correlation, linear polarization. 1S9Hg deduced levels, J, 7c, y-mixing. Ge(Li), Ge(HP) detectors.

Rotation aligned bands and configuration dependent interaction in189Hg

“…A singles 7-ray spectrum measured at 90 ~ with respect to the beam direction is shown in Fig. The normalization is consistent with the A 2 and A, values observed by Bourgeois [6]. The relatively high background is partly due to the compound system and partly due to the radioactive decay of evaporation residues.…”

“…Routhians, band-crossing frequencies and aligned angular momenta calculated within the cranked shell model [14] agree very well with experimental values for 19~ [8,13]. Previous work [6] on 189Hg established the yrast sequence up to the (37/2 + ) state and one side band up to the (33/2-) state. The aim of the present work is to extend the investigation of these extreme alignment phenomena to the odd neutron system 189Hg and to study the blocking of pair-excitations by the valence particles.…”

“…6 the crossing frequencies co~ deduced from high spin band structures in ass-198Hg [1,2,[6][7][8][9][10] are plotted as a function of neutron number N. The figure includes data on the AB and B C pair breaking with spectators built of the vacuum, A, E, F, AE and AF configurations. 6 the crossing frequencies co~ deduced from high spin band structures in ass-198Hg [1,2,[6][7][8][9][10] are plotted as a function of neutron number N. The figure includes data on the AB and B C pair breaking with spectators built of the vacuum, A, E, F, AE and AF configurations.…”

“…The Hg isotopes have been extensively investigated, both experimentally [1][2][3][4][5][6][7][8][9][10] and theoretically [11][12][13]. Of particular interest is the description of their high spin structure in terms of rotation aligned quasiparticle states and bands built on these states.…”

Collective structures in185Hg

“…In the odd-A isotopes a rotation-aligned vi 13/2 quasiparticle band structure is the fingerprint of small oblate deformation for nuclei with A=> 189 [7,8]. The use of large efficiency 4re-array detectors for 7-spectroscopy has led to a major progress in the study of the neutrondeficient odd-A mercury isotopes.…”