A new angular momentum expansion of level energies of ground-state band of even-even nuclei has been obtained which is found to converge rapidly even for the most back-bending nuclei. Attempts have been made to interpret the parameters and calculate them microscopically. It is found that nuclear structure in the forward bending region is quite different compared to that in the back-bending region.

The mechanism of target fragmentation phenomena is explored in a statistical model. It is shown that peripheral interaction arising out of large impact parameter can describe the mass yield distribution of the products from the fragmentation of⁶³Cu by the bombardment ofp,¹²C and⁴⁰Ar with energies of 28, 25 and 80 GeV respectively. Important insights into the dynamics is obtained from these reactions as the target remaining the same, the projectile mass varies by forty units and the incident energy per nucleon by fourteen units. Surface properties of the target and projectile are shown to play an important role. Other features like limiting fragmentation and projectile dependence are also borne out in this study.

The ground-state energy of an atomic nucleus with asymmetryβ is considered to be equivalent to the energy of a perfect sphere made up of the infinite nuclear matter of the same asymmetry plus a residual energyη called the local energy,η represents the energy due to shell, deformation, diffuseness and exchange Coulomb effect etc. Using this picture and the generalized Hugenholtz- Van Hove theorem of many-body theory a new mass formula has been developed. Based on this, a mass table containing the mass excesses of 3481 nuclei in the range 18 ⩽A ⩽ 267 has been made. This mass formula is compared with other mass models.

A possible mechanism for the occurrence of nuclear fusion at room temperature is presented. Neutralization of the positive charge of the deuteron nucleus by its orbiting electron due to large enhancement of effective mass results in the vanishing of the Coulomb barrier which facilitates fusion at room temperature.

The potential between two¹²C nuclei in linear chain configuration has been calculated microscopically using the Ali-Bodmerα-α potential. This potential shows a pocket and compares well in the tail region with the phenomenological potential extracted before, from the data on the quasi-molecular resonances of the¹²C +¹²C system. This provides support to the diatomic like rotation-vibration picture of quasi-molecular states.

The nuclear molecular resonances observed in α+¹²C and α+¹⁶O systems are described in a diatomic-like molecular picture using a Morse-type bonding potential. The depths of the bonding potentials are found to be 11.5 MeV and 11 MeV respectively, with long range of about 15 fm. Both the bound and resonance states of these potentials are calculated which compare quite well with the observed states. The diatomic-like rotational and vibrational picture of the quasi-molecular states proposed earlier for¹²C+¹²C system system is found to be quite valid for α+¹²C and α+¹⁶O systems. In these two systems, the rotational vibrational characteristics are equally well pronounced as in the¹²C+¹²C system.

Time of flight and energy of fission fragments were measured using pulsed beam. Fission fragment mass and energy integrated angular distributions were extracted. Fission fragment anisotropy was explained in the framework of saddle point model.