Systematic study of rigid triaxiality in Ba–Pt nuclei and role of $$Z=64$$ Z = 64 subshell effect

Quasiparticle structure of low-lying yrast energy levels and $$\gamma $$-bands in $$^{164{-}174}$$Hf nuclei

“…Thus, for 164 Hf the yrast band is arising due to ground band upto spin I = 8 + h. At I = 10 + h, (1,2p) is contributing to the yrast band and for I ≥ 12 + h yrast band is Fig. 2 The labels (0,0), (2,0), (4,0), (1,2n), (3,2n), (1,2p), (3,2p), (2,4) and (4,4) in the band diagrams of 164−174 Hf correspond to ground, γ -, 2γ -, 2n-aligned band, γ -band built on this 2n-aligned state, 2p-aligned band, γ -band built on this 2p-aligned state, (2n+2p) aligned band and γ -band built on this 4-quasiparticle band…”

“…Indeed, the question of whether nonaxially-symmetric nuclei are γ -soft or triaxial has been an ongoing and active issue in nuclear structure physics for over 50 years. However, despite considerable effort, the precise description of axially asymmetric shapes and the resulting triaxial quantum many-body rotors still remain an open problem [1][2][3][4][5]. Theoretically, triaxiality has been envisaged for a long time but explicit experimental evidences have only been found in recent years.…”

Effective triaxiality of even-even nuclei with quadrupole and octupole deformations

“…Many approaches exist for calculating the asymmetry parameter γ eff from experimental observables such as R 4/2 =E 4+ /E 2+ and B(E 2 ). Davydov and Filippov [6] used this ratio to determine γ eff , as well as Varshni and Bose estimated γ eff by using the ratio R 4/2 [5]. And the calculation of γ eff from B(E 2 ) values leads to ambiguous values of γ eff and more reliable values are expected from the level energies [5].…”

“…Davydov and Filippov [6] used this ratio to determine γ eff , as well as Varshni and Bose estimated γ eff by using the ratio R 4/2 [5]. And the calculation of γ eff from B(E 2 ) values leads to ambiguous values of γ eff and more reliable values are expected from the level energies [5]. But an estimation of asymmetry parameters of quadrupole and octupole deformations η eff and γ eff was not carried out.…”

“…At γ = 0 and γ=π/3 it corresponds to the axially symmetric prolate and oblate shapes, respectively. The intermediate values of γ, within 0<γ<π/3, give the triaxial shapes [4][5][6].…”