Bulg. J. Phys. vol.48 no.5-6 (2021), pp. 645-654



Shapes and Symmetries in A ∼ 130 Nuclei: A Perspective through Measured Transition Probabilities

P. Das, U. Lamani, H.K. Singh
Physics Department, Indian Institute of Technology Bombay, Powai, Mumbai-400076, India
Abstract. We investigated two isotones (N = 74) — 129Cs and 127I in the mass region 130 — both with moderate deformation, exhibiting signature splitting in their positive-parity bands based on the πg7/2 configuration. Interestingly, signature inversion occurs in 127I at low spin (19/2+), while no inversion has been observed for 129Cs. Here we present some new results on the reduced transition probability B(E2) for states belonging to 127I. The lifetimes in picoseconds were measured using the Doppler Shift Attenuation Method (DSAM). We utilized the single quasi-particle rotor model to theoretically describe our results, which suggest higher deformation and triaxiality (ε2 = 0.23, γ = 28° in Lund convention) for 127I than for 129Cs (ε2 = 0.15, γ = 18°).

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