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Spin distributions for various evaporation residues populated via complete and incomplete fusion of 16 O with 124 Sn at 6.3 MeV/nucleon have been measured, using charged particles (Z = 1, 2)-γ coincidence technique. Experimentally measured spin distributions of the residues produced as incomplete fusion products associated with "fast" α-and 2α-emission channels observed in the "forward cone" are found to be distinctly different from those of the residues produced as complete fusion products. Moreover, "fast" α-particles that arise from larger angular momentum in the entrance channel are populated at relatively higher driving input angular momentum than those produced through complete fusion. The incomplete fusion residues are populated in a limited, higher-angular-momentum range, in contrast to the complete fusion products, which are populated over a broad spin range.The study of incomplete fusion (ICF) of heavy ions with different targets has been a topic of renewed interest at energies above the Coulomb barrier [1][2][3][4][5]. Observations show that at incident projectile energies above the Coulomb barrier, the dominant nuclear reaction mechanisms are complete fusion (CF) and the ICF [6-9]. Efforts are in progress to gain better understanding of ICF processes. Britt and Quinton [10] first observed the production of forward-peaked "fast" α particles in the breakup of the projectiles 12 C, 14 N and 16 O at ≈10.5 MeV/nucleon energy. Advances in the understanding of ICF dynamics were made after the charged particle-γ coincidence measurements by Inamura et al. [11]. Semiclassical theory of heavy ion (HI) interaction categorizes the CF and ICF processes on the basis of driving input angular momentum imparted in the system. In the CF process the driving input angular momentum 0 crit , in accordance with a sharp cutoff approximation [12][13][14] and may be understood in the following way: In CF, the attractive nuclear potential overcomes the repulsive Coulomb and centrifugal potentials in central and near-central collisions. Consequently, CF takes place at a small impact parameter value at which the formation of fully equilibrated compound nucleus (CN) takes place. However, at relatively higher values of impact parameter, the repulsive centrifugal potential increases and hence the dominance of attractive nuclear potential ceases to capture the entire projectile. Therefore, an incompletely fused composite system comprising a part of a projectile plus the target appears in the exit channel that leads to the ICF process, wherein the involvement of driving input angular momentum is relatively larger than that needed for the CF process to take place. At this stage if the driving input angular momentum exceeds the critical limit ( crit ) for CF, no fusion can occur unless a part of the projectile is emitted to release excess driving input angular momentum. As such, prompt emission of a part of the projectile (predominantly α clusters in 12 C, 16 O and 20 Ne beam) takes place to provide sustainable input angular momenta to t...

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The odd mass nucleus 137 Pr has been studied to high spins in order to investigate the magnetic rotation phenomenon in mass 130 region using the 122 Sn( 19 F, 4n) 137 Pr reaction at a beam energy of 80 MeV. A known I = 1 band has been extended to J π = 47/2 − with the addition of three new transitions. Directional Correlation of Oriented Nuclei (DCO) ratios and linear polarization measurements have been performed to assign the multipolarities of gamma transitions and the spins and parities of the energy levels in this band, now established as the M1 band. The combination of M1 transitions along with cross over E2 transitions have been observed in this band for the first time. The experimentally deduced B(M1)/B(E2) ratios show a decrease with increasing spin after band-crossing suggesting magnetic rotation. TAC calculations for the 3qp: πh 11/2 ⊗ ν(h 11/2 ) −2 configuration reproduce the experimental observations in the lower spin part of the I = 1 band and the 5qp: πh 11/2 (g 7/2 ) 2 ⊗ ν(h 11/2 ) −2 configuration reproduces the I = 1 band at higher spins; the crossing of the bands based on the two configuration leads to a back-bending also. Theoretical calculations also support a magnetic rotation nature for both the configurations.