High-resolution study of excited states in 158Gd with (p,t) reactions

TL;DR

This study provides a high-resolution analysis of excited states in 158Gd using (p,t) reactions, identifying numerous states and rotational bands, and compares experimental data with IBM theoretical models.

Contribution

It offers a detailed level scheme for 158Gd, including many new 0+ states, and performs statistical and model comparisons to enhance understanding of nuclear structure.

Findings

Identification of 36 excited 0+ states, including five tentative.

Observation of rotational bands and analysis of moments of inertia.

Comparison of experimental data with IBM calculations showing good agreement.

Abstract

The excitation spectra in the deformed nucleus 158Gd have been studied with high energy resolution by means of the (p,t) reaction using the Q3D spectrograph facility at the Munich Tandem accelerator. The angular distributions of tritons were measured for more than 200 excited states seen in the triton spectra up to 4.3 MeV. A number of 36 excited 0+ states (five tentative), have been assigned by comparison of experimental angular distributions with the calculated ones using the CHUCK code. Assignments for levels with higher spins are the following: 95 for 2+ states, 64 for 4+ states, 14 for 6+ states and about 20 for negative parity states. Sequences of states which can be treated as rotational bands are selected. The analysis of the moments of inertia defined for these bands is carried out. This high number of excited states in a deformed nucleus, close to a complete level scheme, constitutes a very good ground to check models of nuclear structure. The large ensembles of states with the same spin-parity offer unique opportunities for statistical analysis. Such an analysis for the 0+, 2+ and 4+ states sequences, for all K-values and for well-determined projections K of the angular momentum is performed. The obtained data may indicate on a K symmetry breaking. Experimental data are compared with interacting boson model (IBM) calculations using the spdf version of the model. The energies of the low-lying levels, the transition probabilities in the first bands and the distribution in transfer intensity of the 0+ states are calculated and compared with experiment.