Pre-equilibrium particle emission due to heavy and light ion interactions

Abstract

To understand the mechanism of pre-equilibrium particle emission using light and heavy ion beams with different targets at energy above the Coulomb barrier, a study has been done. The cross-sections for twelve systems ⁴He + ⁵⁹Co, ⁴He +¹²⁴Sn, ⁴He + ¹⁶⁵Ho, ¹²C + ⁵⁹Co, ¹²C +¹²⁴Sn, ¹²C + ¹⁶⁵Ho, ¹⁶O + ⁵⁹Co, ¹⁶O + ¹²⁴Sn, ¹⁶O + ¹⁶⁵Ho, ¹⁹F + ⁵⁹Co, ¹⁹F + ¹²⁴Sn and ¹⁹F + ¹⁶⁵Ho have been calculated using the statistical model code ALICE-91. Significant pre-equilibrium particle emission contribution has been obtained for lighter systems at higher projectile energy. It has also been found that the pre-equilibrium particle emission affects predominantly over the equilibrated compound nucleus emissions at high projectile energies. Pre-equilibrium fraction (F_PEQ) has been deduced from the excitation function data for different systems at different projectile energies. The present results indicate that the probability of pre-equilibrium particle emission depends not only on a single entrance channel parameter, but it also depends on various entrance channel parameters, namely: projectile energy, mass of the projectile, mass of the target and entrance-channel mass asymmetry. The present analysis of the data also suggests that the pre-equilibrium particle emission contributes significantly at higher projectile energy for lighter mass projectile and target.