Dynamical equations governing the non-adiabatic collapse of a shear-free spherical distribution of unisotropic matter in the presence of charge are obtained. A brief outline of constructing a model describing collapse of a charged radiating fluid sphere in the set up developed is given.

The reflection and transmission amplitudes are defined from the asymptotic form of the solution of Dirac equation of a charged fermion in the presence of uniform time independent external electromagnetic field (E, H). Schwinger’s effective lagrangian is derived from the reflection and transmission amplitudes. It is found that both the real and imaginary parts of the effective lagrangian agree with Schwinger’s expressions derived from the elegant method of proper time formalism.

The screening of the electric-like charge degrees of freedom of aU(1) ×U(1) dyon by an axion-like domain wall is discussed. Depending on the combination of degenerate minima at the interior and exterior boundary of the spherical domain wall a multiplicity of “screened generated electric-likeU(1) ×U(1) charges” are generated in the region exterior to the domain wall. Such a result demonstrates how aU(1) ×U(1) dyon-domain wall configuration may generate multiplicate phenomena in the early universe from a singleU(1) ×U(1) source.

On the basis of a successful phenomenological current confinement model for gluons we have obtained a closed analytical expression for the confined gluon propagator (CGP) for the specific small frequencies in the co-ordinate space using a translationally invariant ansatz. We have also derived compact expression for generalm-dimensional harmonic oscillator ‘propagator’ for specific energies. Using the CGP the complete expression for the one gluon exchange potential (COGEP) between the quarks has been derived using the Fermi-Breit formalism which will be useful in the study of hadron spectroscopy and hadron-hadron interactions. TheN - Δ splitting is calculated using the spin-spin part of the COGEP.

The effect of change in deuteron size on its elastic scattering from protons and alphas is investigated by varying the Hulthen parameters of the deuteron wave function in the scattering process. The cross sections forp-d scattering, calculated in the Born approximation, are found to increase substantially at backward angles even when the deuteron size is reduced by a small amount, whereas the shape of the angular distribution does not change significantly. For theα-d elastic scattering, interaction potential is obtained by folding the deuteron wave function and the optical potential for nucleon-scattering. The cross sections calculated atE_d = 13·7 MeV, shows that the first minimum around Θ_cm = 60° is deepend as the deuteron size is reduced, while at 52 MeV bombarding energy, the size effects are not very distinct. These observations are useful in the interpretation of deuteron cluster knockout reactions.

A multiple foil holder for use in ultra high vacuum (UHV) environment as a post accelerator ion stripper has been designed and fabricated. It is used to produce beams of an ion in different charge states at a given energy from a 14 MV pelletron accelerator. These ions are required in several types of atomic collision experiments. The assembly is tested with³²S ions at various energies.

The angular distribution of fission fragments in alpha induced fission has been studied at an incident energy of 55 MeV in¹⁹⁷Au target. The relative differential fission cross sections were measured at different angles between 10° and 170° and the resulting angular distributions fitted by least squares method with Legendre polynomials. In the present work, a correction for the self-scattering and self-absorption of fission fragments in the target itself was applied and a target of 3 mg/cm² was used to get good statistics. The anisotropy for 55 MeV alpha induced fission of gold was 2·83±0·43 and the fission cross section calculated by integrating the measured angular distributions over all the solid angles was 5·2±1.0 mb, confirming the value of 4·0±0·05 mb reported by Burnettet al but contrary to the high value of 10±3 mb reported by Ralarosyet al.