Diffuseness in ℓ-distribution: observation of in-complete fusion at ℓ < ℓcrit

The interest to study the in-complete fusion (ICF) reactions at energies ≈ 4-7 MeV/nucleon has aroused during the last decade due to the observation of these reactions at such low energies, where complete fusion (CF) is expected to contribute dominantly to the total fusion cross-section. In case of CF, the projectiles for ℓ < ℓcrit merge with the target nucleus, with the dominance of the nuclear force field, leading to the formation of completely fused excited composite system. However, in case of ICF, for the values of ℓ > ℓcrit, the projectile may break-up into clusters, one of which may fuse with the target nucleus, forming the reduced excited composite system with relatively less mass, charge and excitation energy as compared to completely fused composite system. The remnant flows in the forward direction with almost beam velocity. Due to the partial fusion of the projectile, the fractional momentum transfer takes place in the ICF processes. Each of these processes (CF and ICF) leads to the characteristic velocity distribution of the reaction residues