Spin assignment and behavior of superdeformed bands in A\\sim 150 mass region

Authors: ALI KHALAF, MANAL SIRAG, MAHMOUD TAHA

Abstract: The smoothed experimental dynamical moment of inertia J^{(2)} values were fitted with a theoretical version using the Harris three parameter formula in even powers of angular frequency \omega, derived for results from the cranking model. The expansion parameters were adjusted by using a computer simulated search program. The best expansion parameters from the fit were used to assign the spins of the superdeformed (SD) rotational bands (RB) by integrating the calculated J^{(2)}. The data set includes 23 RB's in 11 SD nuclei, which show no evidence of either irregular behavior near the bottom of the bands or abrupt angular momentum at low rotational frequency in the mass region ranging from A = 142 to A = 154. We used the differences of angular momenta at constant frequency as effective alignment. The relative properties of superdeformed rotational bands (SDRB's) are analyzed in terms of the effective alignment of the valence nucleons. The effective alignment is a powerful tool to assign the configurations, to select the identical bands as well as to predict new SD bands from other combination of the orbitals. The \Delta I = 2 energy staggering observed in 3 of our selected SDRB's are also described from a smooth reference representing the finite difference approximation to the fourth derivative of the \gamma-ray transition energies.

Keywords: Superdeformed rotational bands, nuclear effective alignment, identical bands, nuclear staggering

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