An attempt is made to study the symmetry energy at the time of primary fragment formation from the experimentally observed cold fragments for a neutron-rich system of ^64Ni ＋ ^9Be at 140 MeV/nucleon,utilizing the recent finding that the excitation energy becomes lower for more neutron-rich isotopes with a given Z value.The extracted α（sym）/T values from the cold fragments,based on the Modified Fisher Model（MFM）,are compared to those from the primary fragments of the antisymmetrized molecular dynamics（AMD） simulation and become consistent with the simulation when the I = N —Z value becomes larger,indicating that the excitation energy of these neutron-rich isotopes is indeed lower.
In this report,a kinematical focusing technique will be briefly described,and using this technique,the primary hot isotope yields from the multiplicities of evaporated light particles,associated with isotopically identified intermediate mass fragments,are reconstructed.Symmetry energy and characteristic properties of the fragmenting source at the time of the intermediate mass fragment formation are extracted from these reconstructed primary isotope yields using a self-consistent manner.The extracted density-dependent symmetry energy is further compared with those experimentally extracted from other heavy-ion reactions in literatures.A direct connection between the freeze-out concept and transport model simulations in a multifragmenting regime of heavy-ion collisions is also demonstrated quantitatively in the present work.
The two-photon interactions[1]for charmonium at unprecedentedly high energies can be studied in ultra-peripheral heavy ion collisions at Relativistic Heavy Ion Collider(RHIC),Large Hadron Collider(LHC),and Future Circular Collider(FCC)energies.We investigate the semi-coherent two-photon processes for large-pT charmonium(J=)production in proton-proton and nucleus-nucleus collisions at RHIC,LHC,and FCC energies.
The NRQCD approach[1],which was introduced in 1995,has become the standard framework to study heavy quarkonium physics.In NRQCD,the Fock state structure of heavy quarkonium state is[2]where v is the relative velocity of the heavy quarks in heavy quarkonium.
