E. Wallander

Band structure in 81Sr

The reactions 78Kr( alpha ,n) and 80Kr( alpha ,3n) were used to populate excited states in 81Sr. The de-excitation of these states was studied by in-beam gamma -ray spectroscopy. A number of new high-spin states forming band structures have been observed. Lifetime measurements have also been performed. Theoretical calculations using a particle-rotor approach based on the Nilsson model have been made. The different bands are generally well reproduced.

Low spin, negative parity states in the N = 103 isotones of 171Er, 173Yb and 175Hf identified by thermal neutron capture reactions

Abstract Energies and intensities of the γ-rays following thermal neutron capture in enriched samples of 170 Er, 172 Yb and 174 Hf have been measured using internal reactor targets and a three-crystal Ge(Li) pair and anti-Compton spectrometer. The reaction Q -values, excitation energies and intensity values have been deduced. Decay schemes of 171 Er, 173 Yb and 175 Hf are presented together with the spins and Nilsson assignments of the low-lying rotational bands populated from the capture states.

LOW SPIN STATES IN

The energies and intensities of gamma radiation from thermal neutron capture in an enriched sample of 180Hf have been determined by means of a Ge(Li) pair and anti-Compton spectrometer. An internal reactor target has been used. The reaction Q-value, the energies of the excited states and the decay scheme of 181Hf have been deduced. A large number of low K-value states are found in the range of excitation energy from 1 to 2 MeV.

sup 181

Abstract The reactions 82 Kr(α, n) and 84 Kr(α, 3n) were used to populate excited states in 85 Sr. The deexcitation of these states was studied by in-beam γ-ray spectroscopy. A number of new high-spin states have been observed. Lifetime measurements have also been performed. Some of the levels are interpreted as shell-model states.

Hf FROM THE THERMAL NEUTRON CAPTURE REACTION.

The reactions84Sr(α,n)87Zr and86Sr(α, 3n)87Zr were used to populate excited states in87Zr. The de-excitation of these states was studied by in-beamγ-ray spectroscopy. A number of new high-spin states were observed. Lifetime measurements were also performed. The results are discussed within the frame-works of the shell model and the particle-core coupling model.

High-spin states of 85Sr

Abstract The energies and intensities of γ-radiation from thermal-neutron capture in enriched samples of 176 Yb and 178 Hf have been determined by means of a Ge(Li) pair and anti-Compton spectrometer. Internal reactor targets have been used. The reaction Q -values, the energies of the excited states and their γ-decay have been deduced. The position of the 1 2 − [521] hole configuration in 177 Yb is discussed. A large number of low K -value states are found both in 177 Yb and 179 Hf in the range of excitation energy from 1 to 2 MeV.

A study of87Zr by (α,x n) reactions

Abstract The reactions 80 Kr(α, n) 83 Sr and 82 Kr(α, 3n) 83 Sr were used to populate excited states of high spin in 83 Sr. The de-excitation of these states was studied by in-beam γ-ray spectroscopy. A number of new high-spin states have been observed. The results are discussed within the framework of the Coriolis-coupling model and the cluster-core coupling model.

Thermal-neutron capture investigation of the N = 107 isotones of 177Yb and 179Hf

Abstract Thermal-neutron capture γ-rays from 26 Mg have been measured with a Ge(Li) detector in pair and anticoincidence spectrometer arrangements. An internal target of enriched 26 Mg has been used. The reaction Q -value has been determined. Energies and intensities of the γ-rays are reported and a decay scheme is presented. Absolute thermal-neutron capture cross sections for 24 Mg(n, γ) 25 Mg and 25 Mg(n,γ) 26 Mg have been determined from neutron capture in natural magnesium.

High spin states of 83Sr

The excited states of 35Cl, populated in the 32S(α,p)35Cl reaction at Eα = 12-16 MeV have been studied by γ-γ coincidence, angular distribution and yield function measurements. The spin values 11/2(-), 11/2(-) and 13/2 are proposed for the new states at 5 407, 5 927 and 6 086 keV respectively.

Thermal neutron capture gamma rays from the 26Mg(n, γ)27Mg reaction

Abstract Energies and intensities of γ-rays following thermal neutron capture in enriched 170 Yb have been measured using an internal target and three-crystal Ge(Li) pair and anti-Compton spectrometers. The reaction Q -value has been deduced and a number of new excited states have been found. A decay scheme for the low-lying levels is presented with spin and Nilsson assignments.