A. Pakkanen

Levels in 110Pd, 112Pd, 114Pd and 116Pd from the beta decays of the on-line mass separated Rh isotopes☆

Abstract The energy levels of even 110–116 pd nuclei have been studied from β-decays of odd-odd 110–116 Rh isotopes produced at the on-line isotope separator IGISOL. Two β-decaying states with I π = 1 + and I ⩾4 have been identified in all the cases. New level schemes with preliminary spin assignments have been constructed for 112 Pd, 114 Pd and 116 Pd. Similarities with the level structures of their Xe isotones have been pointed out.

Lifetimes of yrast states in 110Cd

Abstract Lifetimes or lifetime limits of 20 yrast levels in 110 Cd have been measured using the recoil-distance method and the NORDBALL array of Compton-suppressed Ge detectors. From the reduced transition probabilities competing rotational and vibrational behaviour of 110 Cd is revealed. Also non-collective states, associated with proton configurations, have been observed.

Neutron and proton bands in 122Xe at high spins

High-spin bands in 122,123,124Xe and 123Cs were populated using 3He- and 16, 18O-induced reactions on Te, Pd and Ag targets. The subsequent de-excitation was studied using gamma -ray and conversion-electron spectroscopic methods. States with spins up to Jpi =(25-), (35/2-), (21-) and (51/2-), respectively, were identified. In 122Xe four Delta I=2 bands were identified in addition to the ground state and gamma bands, and furthermore a Delta J=1 band with a tentative (K,I)pi =(10, 10)- band head was observed. In 123Xe the previously observed 11/2- and 7/2+ bands were extended to Jpi =(35/-) and (23/2+), respectively. The yrast cascade in 123Cs was extended to spin 51/2-. In 124Xe the recently presented level scheme was completed with some high-lying levels. The band structures were interpreted within the cranked shell model (CSM) framework. A consistent description of band crossing frequencies in both odd and even nuclides was obtained, and configurations were assigned to most of the observed bands. Some relative transition rates were obtained from branching intensities.

Structure of odd-A Pm nuclei (I). 147Pm

Abstract The level structure of 147 Pm was studied by methods of in-beam γ-ray and electron spectroscopy using the 148 Nd(p, 2n) reaction. Twenty-four new levels with spins between 1 2 and ( 15 2 ) were observed. The 12 ± 2 ns h 11 2 level at 649.3 keV decays by a strongly hindered El transition (1.2 × 10 −6 s.p.u.) to the 9 2 + level at 408.2 keV and by a M2 transition (0.15 s.p.u.) to the ground state.

The E2/M1 mixing of the transitions from the Kπ = 2+ bands in 190, 192Os and 192Pt

Abstract The directional correlation method was used to determine multipole mixing ratios of several γ-transitions in 190, 192 Os and 192 Pt. A new level at 1406.4 keV has been established in 192 Pt. The experimental E2/M1 mixing ratios of the transitions from the γ-bands have been compared with theoretical predictions of the Greiner model also including the rotation-vibration interaction, the Kumar-Baranger model and the Zackrevsky model.

Particle octupole multiplet in147Gd

Levels of the N=83 nucleus147Gd have been investigated by in-beam γ-ray and conversion-electron spectroscopy using the147Sm(3He,3n) and Sm(α,n) reactions. We have observed 16 new low-and medium-spin levels in147Gd. In addition to the previously known 13/2+ level we have located the 11/2+,9/2+, 7/2+, 3/2+ and (1/2)+ members of the vf7/2×3 septuplet.

Medium-spin states in the N = 80 nuclei 139Pr and 141Pm

Abstract The level structures of 139 Pr and 141 Pm have been investigated using (p, 2n), ( 3 He, 3n) and (α, 4n) reactions and methods of in-beam γ-ray and electron spectroscopy. Fourteen new levels with spins up to ( 23 2 ) + were observed in 139 Pr and seventeen new levels with spins up to 19 2 − in 141 Pm. The level structures in both nuclei can be described by coupling the odd-proton intrinsic states to the excitations of the doubly even core. The ordering of the levels in the π h 11 2 ⊗2 + multiplet is discussed on the basis of the triaxial rotor-plus-particle model calculations. The calculations suggest that a transition from a basically prolate to an oblate triaxial shape takes place between the neutron numbers N = 78 and N = 80. A γ-deformation of 34° was deduced for both 139 Pr and 141 Pm.

Medium-Spin States in the N=82 Nuclei 141Prand143Pm

The level structures of the N = 82 nuclei 141Pr and 143Pm were studied by methods of in-beam γ-ray and conversion-electron spectroscopy using the (p, 2n) and (p, 3n) reactions. The levels schemes have been built up to energy of about 3 MeV and spin of 19/2. In 141Pr we have established 14 new low- and medium-spin levels.

New 204Au activity and the decay of 202Au

Abstract A new 40 ± 3s activity, assigned to 204 Au, has been found by bombarding natural mercury targets with 14–15 MeV neutrons. The decay of this nucleus and 202 Au ( T 1/2 = 29 ± 3s) has been studied employing Ge(Li), NaI(T1) and plastic detectors and coincidence systems. No trace of the previously reported 4.0 ± 1.0s activity of 204 Au was observed.

Isomeric transition in 198Au

An isomeric 115.2 keV transition from the high-spin 2.36 d state in 198Au has been observed. The multipolarity of this transition is probably M4 and it suggests a configuration of (πh112) (vi132)12− for the isomeric state at 811.9 ± 1.5 keV. The multipolarities E2 (+<2%M1) and M1(+< 20% E2) were determined for the 180.30 and 204.13 keV γ-rays, respectively.