Coupling between two extreme excitation mode in weakly deformed $^{142}$Eu nucleus

TL;DR

This paper investigates two opposite parity dipole bands in the $^{142}$Eu nucleus, revealing magnetic rotation and octupole correlations through gamma-ray measurements and theoretical modeling.

Contribution

It provides the first detailed analysis of the coupling between excitation modes in $^{142}$Eu using experimental data and shears mechanism calculations.

Findings

Magnetic rotation dominates the structure of DB II.

Enhanced E1 transitions indicate octupole correlations.

Theoretical models successfully reproduce transition rates.

Abstract

Two opposite parity dipole bandlike structures DB I and DB II of $^{142}$Eu are investigated by the Indian National Gamma Array (INGA), using the fusion evaporation reaction $^{31}$P + $^{116}$Cd @ 148 MeV. The decreasing trend as well as magnitude of the measured $B(M1)$ and $B(E2)$ transition rates of the band DB II has been reproduced well within the shears mechanism with the principal axis cranking model calculations. This calculation reflects the fact that the maximum contribution of the angular momentum of the states in DB II has been generated from the magnetic rotation (MR) phenomenon. The enhanced $B(E1)$ rates of the connecting $E1$ transitions from the states of DB II to DB I are demanding the octupole correlation due to the involvement of the octupole driving pair of orbitals $\pi{h_{11/2}}$ and $\pi{d_{5/2}}$ as evident from the quasiparticle alignment ($i_{x}$), the experimental routhians (e$^{'}$) and the calculated neutron and proton quasiparticle energies against the rotational frequency ($\omega$).