Krishna Kumar

Collectivity of light Ba isotopes in the DPPQ model

Abstract The dynamic pairing plus quadrupole model of Kumar and Baranger is employed for studying variations of the nuclear structure of light Ba isotopes with A =122–134. The potential energy surface parameters have been calculated and the low-spin level spectrum is predicted along with the static and transition E2 moments. Comparison with experiment and with other theories supports the validity of our treatment.

Shape changes of N=66 isotones Mo–Ce in DPPQ model

Abstract The dynamic pairing plus quadrupole model is used to study the changes in nuclear structure of N =66 isotones of Mo–Sn–Ce. Two different single-particle configurations have been used for Z Z ⩾50 regions and their suitability for respective regions is illustrated. The variations with Z of the quadrupole deformation β , deformation energy E d , and the 2 1 + state energy, B (E2;0 + →2 + ) and quadrupole moment Q (2 + ) are reproduced. The role of the spin–orbit partner (SOP) orbitals in n–p interaction for inducing the deformation in each region is studied.

Proton spectroscopic factors of Sm isotopes in the pairing-plus-quadrupole model☆

Abstract Proton spectroscopic factors have been calculated for the single-proton states in Sm isotopes with N = 84–92 by using the deformed quasiparticle wave functions obtained in the pairing-plus- quadrupole model. Comparison is given with the experimental data from the pick-up reactions (d, 3He) and (t, 4He) to the product nuclei 145–153Pm. Effects of deformation on the spectroscopic factors are studied.

Predictions for Superheavy Nuclei

The Dynamic Deformation Model has been extended to the problem of fission in such a way that several thousand channels including particle-decay, α-decay, heavy-ion-emission, asymmetric fission, and symmetric fission can be taken into account. The model also includes a Kinetic Shell Correction which was ignored in previous predictions for Superheavy nuclei. This model is in better agreement with experimental life-times. A new location of the Superheavy peak is predicted at Z = 116 (eka-Polonium), A = 300, total half-life = 1079 years. New heavy-ion-fusion experiments and the means of identifying the Superheavy Elements are suggested.

Vanishing quasiparticle energies in the BCS theory and a practical solution

Abstract The problem of vanishing quasiparticle energies in the BCS theory is outlined, and a practical solution is reviewed which not only removes the problem but improves the theory in all cases without requiring a substantial increase in the computation time. This solution also removes a major deficiency of the BCS theory, emphasized by Belyaev. The particle-hole channel of the pairing interaction, neglected in the BCS, is taken into account. Moreover, second-order constraints in N 2 , emphasized by Lipkin and Nogami, are included automatically in the Improved BCS theory reviewed in this paper. Thus, the particle-number constraint is improved without the complications of the particle-number projections.

The change of sign of E2 and M1 matrix elements, and of δ-values of166Er at high spins

Calculations of the Dynamic Deformation Model for the E2/M1 mixing ratios for ψ-band to ground-band transitions in166Er have been extended to higher spins (up to I=20). Previous comparisons with the experimental values and with the IBA-1 predictions, available at present up to spins 8 only, are also included for the sake of completeness. Additional comparison with the Frankfurt Model is also given. While all three models give reasonable magnitudes of the mixing ratios, only the DDM gives the sign changes at the correct spin values. Predictions are presented for additional sign changes of the mixing ratios, as well as those of the E2 and the M1 transition moments.