Phase transitions and shape deformations in high spin nuclei

In recent years a renewed interest in the investigation of phase transition has emerged as an exciting area [1]. It is really a fascinating and still open question whether phase transitions do exist in finite systems of nuclei at finite temperature and signature of these transitions remains regardless of fluctuations. This thesis is devoted to the study of the microscopic aspects of phase transitions and shape deformations especially the interplay between spherical, deformed and superdeformed shapes. In order to study the phase transitions in detail, a statistical theory has been modified incorporating temperature, deformation, angular momentum, collective and non collective rotational degrees of freedom, shell effects and pairing correlations. The basic ingredient to the statistical theory is a suitable shell model level scheme and has used cranked Nilsson Strutinsky (CNS) formalism. Pairing-phase transitions from superfluid to normal state and shape-phase transitions such as deformed to spherical shape, prolate to oblate shapes with increasing temperature and angular momentum are observed. The interplay of various degrees of freedom and their influence on the behavior of nuclei that are of current interests are studied with particular focus to level density, level density parameter, nucleon separation energies and nuclear specific heat to explore these transitions in detail.