2025/08/13 by Reece, M., Coombes, B. J., Mitchell, A. J. +9
#FOS: Physical sciences #Nuclear Experiment (nucl-ex) #Nuclear Theory (nucl-th)
paper · doi:10.48550/arxiv.2508.09643
The low-lying energy spectra of even-even tellurium isotopes near midshell have long been interpreted as `textbook' examples of vibrational collective motion. However, in many cases electric-quadrupole observables, which are a particularly sensitive probe of collectivity, remain undetermined. Coulomb-excitation measurements were performed to measure transition strengths connecting the ground and low-excitation states in 124Te. This isotope lies at a transitional point between collective structure near the neutron midshell and seniority structures near the N=82 shell. A transition strength, B(E2; 61+ → 41+), of 27(9)~W.u. was measured for the 6+1→4+1 transition for the first time in this nucleus; this value is significantly below that expected for a spherical vibrator, as well as other collective models. We examine the transition strengths in 124Te and its neighbors by comparison with large-basis shell-model calculations and by comparison with General Collective Model (GCM) fits. A GCM description of 120Te agrees with experimental E2 transition strengths, but no comparable description of 124Te is possible with the GCM. In contrast, there is remarkably good agreement between the B(E2; 61+ → 41+) values and shell-model calculations for 124-134Te. It appears that, despite approaching midshell, 124Te retains a seniority structure for the 6+1 level, i.e. a significant π0g7/22 contribution. This persistence of the shell structure at the 6+1 state is in contrast to the B(E2) values of the lower-excitation 2+1 and 4+1 states in 124Te, and neighboring 120Te and 122Te, for which the collectivity becomes enhanced as more neutrons are removed from N=82.