Multipole mixing ratio of the 2+2 → 2+1 transition in 132Te

Determine the multipole mixing ratio δ for the 2+2 → 2+1 γ-ray transition of the neutron-rich nucleus 132Te, thereby quantifying the relative M1 and E2 components beyond the current constraint δ < 0.38 inferred from Coulomb-excitation yields and vibrational-limit considerations.

Background

Identification of the one-phonon mixed-symmetry 2+ state in 132Te relies on the strength of the M1 transition to the fully symmetric 2+1 state. While the present work precisely determines the lifetime of the 2+2 state and establishes a large M1 strength consistent with a mixed-symmetry assignment, the exact multipole mixing ratio for the 2+2 → 2+1 transition remains undetermined.

The authors provide a physics-based upper bound on the E2 admixture (δ < 0.38) using the vibrational limit and existing Coulomb-excitation data, but emphasize that a direct determination of δ is still needed for a fully quantitative characterization of the transition multipolarity.