Compound and non-compound nuclear fusion using forward recoil range distributions of evaporation residues produced in 18O+154Sm system

The study investigates partial linear momentum transfer in the non-compound nuclear fusion (NCNF) process by analyzing the forward recoil range distributions (FRRDs) of evaporation residues (ERs) produced in the ${}^{18}$O+${}^{154}$Sm system at projectile energy $\approx$ 5.27 MeV/nucleon. The ERs formed through xn and pxn evaporation channels exhibit single-peaked gaussian distributions in forward recoil ranges while their range-integrated cross sections alines well with theoretical prediction of PACE-4 code. These results show the signature of complete momentum transfer and formation of a compound nucleus ${}^{172}$Yb*. However, ERs produced via $\alpha$ spectator channels shows single peaked gaussian distribution in forward recoil ranges but with a shorter mean ranges and larger cross sections than theoretical predictions. This result suggests that partial momentum transfer results from the breakup of ${}^{18}$O into ${}^{14}$C+$\alpha$, contributing to the formation of an intermediate ${}^{168}$Er* composite system. To investigate isotopic effects on NCNF dynamics, reactions induced by ${}^{16}$O and ${}^{18}$O projectiles were compared within the framework of Z${}_P$Z${}_T$ and total asymmetry (${\mu }_{cm}^T$). At energies $\approx$ 10$\%$ above the coulomb barrier, both projectiles exhibit comparable NCNF contributions. However, at projectile energies $\ge$ 30$\%$ above the Coulomb barrier, ${}^{18}$O exhibits a significantly higher NCNF contribution as compare to ${}^{16}$O. Further, the critical angular momentum increases exponentially with both Z${}_P$Z${}_T$ and ${\mu }_{cm}^T$, establishing these parameters as key factors in onset of the NCNF process. Additionally, the study finds also that fusion suppression depends on projectile’s $\alpha$-separation energy. A generalized expression is proposed to estimate NCNF contributions for reactions involving both weakly and strongly bound projectiles on ${}^{154}$Sm.