Pragya Das

WEB-Spline–Based Multigrid Methods for the Stationary Stokes Problem

We discuss a multigrid technique in solving a large system of linear algebraic equations arising in the approximation of Stokes equations by a new strategy based on weighted extended B-spline (WEB-spline) methods. Three types of WEB-spline–based Stokes elements satisfying the inf-sup condition are considered. First for a linear-constant type of Stokes element, we give the detailed multigrid algorithm and its convergence proof. The convergence proof of the multigrid algorithm for a bubble-stabilized WEB-spline–based Stokes element is dealt with separately. Multigrid method in the case of bubble-condensed variational form is simplified using the techniques from the bubble-stabilized case.

Incomplete fusion studies near Coulomb barrier: a modified sum rule model

The excitation functions of the evaporation residues, produced via complete fusion and incomplete fusion reactions of 11B + 122Sn, were measured for the projectile energy of around 6 MeV/A by the off-line gamma spectrometry. The cross sections have been compared with the statistical model code Projected Angular Momentum Coupled Evaporation (PACE4). The original sum rule model underestimated the ICF cross sections. We therefore made modification in the model mainly to incorporate the energy dependence in the definition of critical angular momentum. Using this modified sum rule model, we found a significant improvement in the results.

Decoupling behavior inLa132

Heavy-ion fusion reactions {sup 122}Sn({sup 14,15}N, xn){sup 132}La have been utilized for the lifetime measurements using the recoil distance method. The lifetimes of seven low-lying excited states were obtained. In addition, the lifetimes of two states belonging to a band, which was identified as a decoupled band, were obtained. The decoupling behavior in {sup 132}La has been theoretically investigated using the particle-rotor model in the model space of {pi}h{sub 11/2} and ({nu}s{sub 1/2}, {nu}d{sub 3/2}). The pseudospin coupling model was also utilized to understand the decoupling behavior in terms of the valence-particle configuration {pi}h{sub 11/2}({Omega}{sub {pi}}=(1/2)) x {nu}[411-tilde]({Omega}{sub {nu}}=(1/2),(3/2)), and a reasonable agreement with the experiment was obtained.