M. Rajasekaran

Neutron Separation Energies of Extremely Neutron Rich Excited Nuclei from Z=30 to 70

Neutron rich nuclei in the medium mass region with thermal excitation and rotational energies, are investigated. A macroscopic-microscopic approach to reproduce the ground state separation energy combined with statistical approach for the excited rotating nuclei yields good results. Shell effects and shape transitions due to rotation alter the boundary of the drip line considerably at low temperatures and with increasing temperature the drip line is lowered to less neutron rich nuclei.

Structural changes in high spin nuclei

Abstract The interplay of various degrees of freedom and their influence on the behaviour of nuclei formed as fused compounds in heavy-ion reactions is investigated. A statistical theory which incorporates deformation, collective and noncollective rotational degrees of freedom and shell effects is developed to study highly excited fused compounds which deexcite by particle emission and yrastlike cascades. We find that the nucleonic separation energies, which are functions of spin and temperature, decrease rather sharply for particular angular momentum states of the nuclei due to shape transitions. We predict an enhancement of nucleonic emission at these spins, and evidence for this is already present in the experiment of Henss et al. Results for heavy systems like Er, Yb and Hg which emit neutrons while rotating fast, and for light nuclei like 28 Si, etc. which have greater probability for emitting protons and light charged particles, are presented.

NEUTRON EMISSION SPECTRA OF EXCITED 126–140Sn NUCLEI

We investigate one-neutron and two-neutron emission from 132Sn and its neighboring isotopes due to thermal excitation. The rotational states of 132Sn at different temperatures are investigated. The effects of separation energy and thermal excitation energy on neutron emission probability are studied.

SHELL DEFORMATION AND SPIN EFFECTS IN NUCLEON SEPARATION ENERGIES

A new formula to obtain shell correction to separation energy is derived from a Strutinsky type calculation. A systematic analysis of shell and deformation effects on nucleon separation energy is made. Spin induced structural changes are also evident in shape changes along the spin coordinate. Calculations are performed for a wide range of nuclei from Zr to Cm. The results are generally in very good agreement with experimental analysis.

Finite size nucleonic effects in the nuclear medium

The finite size effects of nucleons inside a nucleus is investigated. This new approach is entirely different from Hagedorn’s volume correction method and is more rigorous. The size of the nucleon is varied and the magnitude of the hard-core potential is extracted by minimising the energy with respect to the nuclear radius.

Statistical theory of hot nuclei and high spin states

The hot rotating compound systems formed in heavy ion collisions are studied using the statistical theory with a view to determine the spin and temperature dependence of nuclear shapes. Shape transitions are observed for these systems at particular spin values. The neutron and proton separation energies for heavier high spin systems have been evaluated. Results are presented for70170Yb and78194Pt.