Isospin fluctuations and triaxial deformation are incorporated in the statistical theory of hot nuclei, and various nuclear parameters are extracted as functions of isospin, temperature, and deformation for nuclei around Zr. Shape changes are observed with changes in isospin and temperature. Above a particular temperature the shape is found to remain unchanged for all isospins. Constant entropy lines are drawn and yrast traps are observed. The yrast traps at the low entropy values indicate the neutron-proton shell closure for the systems considered. A shift in the yrast minima towards lower isospin is predicted with increase in entropy. At higher entropy values yrast minima are found to disappear. The neutron-proton asymmetry parameter calculated for A=90, 92, 94, and 96 is found to depend strongly on deformation and isospin at low temperatures. For all these nuclei the asymmetry parameter is found to be a maximum for isospins corresponding to stable neutron-proton combination. The single-particle level-density parameter for A=90 extracted as a function of temperature for various isospins shows a minimum at a total isospin of τ=5, indicating the higher stability of this isospin state. At higher temperatures the empirical value of a≊A/10 is reproduced.

• Received 21 November 1991

DOI:https://doi.org/10.1103/PhysRevC.45.1667