Examination of phenomenological formulae in superdeformed bands of A ∼ 190,150 mass regions

The rotational energy formulae viz. VMI model, ab-formula, Harris ω2 expansion, Exponential model with pairing attenuation and Nuclear softness formula are employed to the superdeformed bands of A ∼ 190 and A ∼ 150 mass regions in order to test the validity of various rotational energy formulae in describing the general nature of superdeformed bands. These formulae are used to deduce the band-head spins of the nine superdeformed bands in A ∼ 190 mass region and two superdeformed bands of A ∼ 150 mass region. The band-head spins of these superdeformed bands have been established experimentally and hence they prove to be excellent candidates to examine the adequacy of rotational energy formulae in superdeformed bands. The least-squares fitting of γ-transition energies is performed to calculate the model parameters such as the band-head moment of inertia, the effective pairing gap parameter and the softness parameter, and a careful analysis of these parameters is made. For the first time, we have performed a systematic study of the rotational energy formulae to establish which formula gives the best estimate of spin in A ∼ 190, 150 mass regions.