Abstract
The variation in nuclear deformation with angular momentum is considered in nuclei with A = 40 using the summation method extended to high spin. Pairing is not included in the formalism which is found to be of minor importance in light nuclei. Our results show that, the considered nuclei, undergo a shape transition from spherical to oblate and then to triaxial at high spin. For the extended calculations upto I = 60 ?, Jacobi shape transitions are not obtained for the present candidates. Role of thermal fluctuations on the shape transitions of hot rotating nuclei is studied using Landau theory of shape transitions. With thermal fluctuations the averaged shape lead to triaxial at high excitation energy.