[2311.09713]

Search for the origin of wobbling motion in the $ A \approx 130 $ region: The case of $^{131}$Xe


In-beam $ γ$-ray spectroscopy of $^{131}$Xe has been carried out to study the structure of the intruder $ νh_{11/2} $ band. Excited states were populated via an $ α$-induced fusion-evaporation reaction at E$ _α = 38 $ MeV. Inspection of $ γγ$-coincidence data resulted in the identification of a new rotational sequence. Based on the systematics of excitation energy, assigned spin-parity, decay pattern, and the electromagnetic character of the inter-band $ ΔI = 1 $ $ γ$-transitions, this sequence is proposed as the unfavoured signature partner of the $ νh_{11/2} $ band. The structure of this band is further illuminated in the light of the triaxial particle rotor model (TPRM). The possibility of wobbling excitation in $ N = 77 $ Xe-Ba-Ce isotones has been explored in a systematic manner.