A. Lampinen

The role of the shape driving h12 neutron orbital in 108Cd

Abstract The nucleus 108Cd has been studied using a heavy-ion reaction and the NORDBALL multi-detector array. The yrast band has been extended to Ip = 24+, and nine quasi-rotational side bands have been identified. The n h 11 2 negative-parity orbital is found to play a dominant role both in the low-spin as well as in the high-spin structure of 108Cd. The first band crossing in the yrast band is caused by the h 11 2 neutrons. The 10+ state of the aligned n( h 11 2 ) 2 configuration decays strongly into a low-lying low-spin intruder-like positive-parity band. It is suggested that this intruder structure is dominated by a non-aligned n( h 11 2 ) 2 configuration. For the first time in this mass region, we report a collective, possibly prolate, M1 band built on the p( g 9 2 ) −2 configuration. The experimental results are discussed in terms of total-routhian-surface and cranked-shell-model calculations.

Band structures in 114Cd and 116Cd from heavy-ion collisions

Abstract Gamma-ray studies of binary products from 84Kr + 116Cd collisions have been carried out. New yrast states in 114Cd and 116Cd as well as an intruder band on top of the second excited 0+ state in 116Cd have been identified. These new data essentially add to the unique systematics of low-lying collective states in even-even Cd isotopes confirming the distinct behaviour of the intruder stater.

High-spin levels in63145Eu82

The level scheme of theN=82 nucleus145Eu has been extended toI=(55/2) andEx=11.2 MeV in an experiment with the Tessa Compton-suppressed Ge detector array using the127I(22Ne,4n) reaction. Most of the complicated and irregular level scheme of145Eu can be interpreted as proton multi-quasiparticle states in comparison to the64146Gd82 core nucleus but also excitations across the neutronN=82 core have been observed.

High-spin states in110Cd

Levels of110Cd have been investigated via the96Zr(18O,4n)110Cd reaction by employing the NORD-BALL array of 17 Compton- suppressed Ge detectors. The yrast band has been observed up to I=28 ħ and 14.2 MeV excitation energy with band crossing at ħωc=0.35 MeV. At least three side bands have been constructed. The negative parity bands experience band crossings at ħωc ≈ 0.45 MeV.

Properties of the 13/2+ isomeric decay in201Hg

The isomeric decay of theT1/2=94 us isomeric state in201Hg was studied in beam via the reaction198Pt(α, n). Gamma-ray and conversion-electron spectra were recorded. From the conversion coefficients, the multipolarities of the two depopulating transitions were determined to beM 2 + 10%E 3 andE 2, respectively. These assignments give the depopulating transitions to be 13/2+ → 9/2− and 9/2− → 5/2−, and these thus substantiate the previous suggestion that the isomeric state hasJπ=13/2+. For the 13/2+ → 9/2−M 2 transition a detailed study ofE 3 andM 4 admixed amplitudes was done. The microscopic properties of the 13/2+ and 9/2− states are discussed, and a comparison to the corresponding ones in199,203,205Hg is made.