Fission of 219,220Ra formed in boron induced reactions
G. Sawhney 1*, M. K. Sharma 1
1 School of Physics and Material Science, Thapar University, Patiala
The study of heavy-ion induced fusion-fission reactions has been an active field for many years. The collision between a heavy ion projectile and a target nucleus may lead to the formation of compound nucleus (CN) as well as non-compound nucleus (NCN). The complexity of heavy-ion reactions generally depends on the charge product Z1 Z2 of the colliding nuclei. The smaller Z1 Z2 product is more suitable for fusion-fission reactions as the coulomb repulsion is minimal. The measurement of fission products and evaporation residues in general provide a comprehensive picture of the process subsequent to collision between projectile and target nucleus. However a sizeable amount of non compound nucleus components like incomplete fusion (ICF), deep inelastic collision (DIC), quasi fission (QF) etc, is observed more so at higher energies and for symmetric reaction partners. However the NCN contribution cannot be ruled out for asymmetric reaction partners as well. In this work we present analysis of the fission excitation functions obtained in very asymmetric 10,11B + 209Bi reactions leading to 219,220Ra  over a wide range of incident energies using Dynamical Cluster Decay Model (DCM)  having deformations and orientations included in it. Our DCM calculated fission cross-sections (σfission) in Figure show an excellent agreement with the experimental data for both the reaction channels. It is important to note that the decay cross-sections are controlled by only one parameter of the model, the neck length parameter ∆R which increases linearly with the increase of centre of mass energy. The work is in progress and it will be of interest to investigate the possibility of non compound nucleus contribution from processes like DIC, ICF, and QF along with compound nucleus contribution in the reaction under consideration.
1. L. R. Gasques, et al., Phy. Rev. C 79, 034605 (2009).
2. R. K. Gupta, et al., J. Phys. G: Nucl. Part. Phys. 32, 345 (2006); Phy. Rev. C 77, 054613 (2008).
The DCM calculated fission cross-sections as a function of centre of mass energy compared with experimental data taking deformation effects upto quadrupole deformations.