Measurement of the Fusion Probability, PCN, for Hot Fusion Reactions

TL;DR

This paper measures the fusion probability (PCN) in hot fusion reactions involving various projectiles and gold, providing new data that align with semi-empirical models based on fissility.

Contribution

It provides the first direct measurements of PCN for multiple reactions, enhancing understanding of fusion dynamics in heavy-ion collisions.

Findings

PCN values range from 0.06 to 1.00 for different reactions.

Measured PCN values agree with semi-empirical fissility dependence.

Data improve understanding of fusion probability in hot fusion reactions.

Abstract

Background: The cross section for forming a heavy evaporation residue in fusion reactions depends on the capture cross section, the fusion probability, PCN, i.e., the probability that the projectile-target system will evolve inside the fission saddle point to form a completely fused system rather than re-separating (quasifission), and the survival of the completely fused system against fission. PCN is the least known of these quantities. Purpose: To measure PCN for the reaction of 101.2 MeV 18O, 147.3 MeV 26Mg, 170.9 MeV 30Si and 195.3 MeV 36S with 197Au. Methods: We measured the fission fragment angular distributions for these reactions and used the formalism of Back to deduce the fusion-fission and quasifission cross sections. From these quantities we deduced PCN for each reaction. Results: The values of PCN for the reaction of 101.2 MeV 18O, 147.3 MeV 26Mg, 170.9 MeV 30Si and 195.3 MeV 36S with 197Au are 0.66, 1.00, 0.06, 0.13, respectively. Conclusions: The new measured values of PCN agree roughly with the semi-empirical system- atic dependence of PCN upon fissility for excited nuclei.