Neutron-rich rare-isotope production from projectile fission of heavy nuclei near 20 MeV/nucleon beam energy

Abstract

We investigate the possibilities of producing neutron-rich nuclides in projectile fission of heavy beams in the energy range of 20 MeV/nucleon expected from low-energy facilities. We report our efforts to theoretically describe the reaction mechanism of projectile fission following a multinucleon transfer collision at this energy range. Our calculations are mainly based on a two-step approach: the dynamical stage of the collision is described with either the phenomenological Deep-Inelastic Transfer model (DIT), or with the microscopic Constrained Molecular Dynamics model (CoMD). The deexcitation/fission of the hot heavy projectile fragments is performed with the Statistical Multifragmentation Model (SMM). We compared our model calculations with our previous experimental projectile-fission data of 238 U (20 MeV/nucleon)+ 208 Pb and 197 Au (20 MeV/nucleon)+ 197 Au and found an overall reasonable agreement. Our study suggests that projectile fission following peripheral heavy-ion collisions at this energy range offers an effective route to access very neutron-rich rare isotopes toward and beyond the astrophysical r-process path.

Neutron-rich rare isotope production with stable and radioactive beams in the mass range A ∼ 40–60 at beam energy around 15 MeV/nucleon

“…We would like to conclude the present study with some comments on the model approaches used in this work. Starting from the microscopic CoMD model used in the dynamic stage, we think that the successful description of the reactions is especially valuable due to the predictive power of the microscopic manybody approach, as we have also seen in our recent works [44,54,17], that does not depend on ad hoc assumptions of the reaction dynamics. We saw that the two-stage CoMD/SMM approach provided good results in comparison with the experimental data.…”

“…Spallation is a standard mechanism to produce rare isotopes in ISOL-type facilities [17]. Projectile fission is very effective to produce neutron-rich light and heavy fission fragments (see, e.g., [18][19][20]). Finally, projectile fragmentation is a universal approach to access exotic nuclei at beam energies typically above 100 MeV/nucleon (see, e.g., [21][22][23][24][25][26]).…”

Microscopic description of proton-induced spallation reactions with the constrained molecular dynamics (CoMD) model

“…We note that for the deexcitation of low energy (ǫ * < 1.0 MeV/nucleon) non-fissionable nuclei [42,43]), the SMM code has been shown to adequately describe the particle deexcitation process as a cascade of emissions of neutrons and light charged particles using the Weisskopf-Ewing model of statistical evaporation. In regards to fission of heavier excited nuclei [40,41], the following approach is followed. A "multifragmentation" threshold value of ǫ * mult = 2.0 MeV/nucleon is defined, above which the SMM statistical multipartition is applied.…”

The Giant Monopole and Dipole Resonances within the Constrained Molecular Dynamics (CoMD) Framework

“…The CoMD model is a semi-classical approach to the nuclear N-body problem, that is applied to a broad range of nuclear dynamics applications. Simulations of peripheral reactions at the Fermi level, near ground state properties, positron-electron pair production and fission [3][4][5][6] are just a few examples of the model applications to date.…”