Channel coupling effects on the fusion excitation functions for {sup 28}Si+{sup 90,94}Zr in sub- and near-barrier regions

• Published in: Physical review. C, Nuclear physics Nuclear physics, 2010-04, Vol.81 (4)
• Main Authors: Kalkal, Sunil, Mandal, S., Verma, Shashi, Saxena, Mansi, Goyal, Savi, Siwal, Davinder, Garg, Ritika, Kumar, Suresh, Singh, R., Madhavan, N., Jhingan, A., Nath, S., Gehlot, J., Varughese, T., Golda, K. S., Muralithar, S., Prasad, E., Sandal, Rohit, Behera, B. R., Pramanik, U. D.
• Format: Article
• Language: English
• Subjects: ANGULAR DISTRIBUTION; COULOMB FIELD; COUPLED CHANNEL THEORY; COUPLING; CROSS SECTIONS; DIFFERENTIAL CROSS SECTIONS; DIRECT REACTIONS; DISTRIBUTION; ELECTRIC FIELDS; EVAPORATION; EVEN-EVEN NUCLEI; EXCITATION FUNCTIONS; FORECASTING; FUNCTIONS; HEAVY ION REACTIONS; INTERMEDIATE MASS NUCLEI; ISOMERIC TRANSITION ISOTOPES; ISOTOPES; LIGHT NUCLEI; MASS SPECTROMETERS; MEASURING INSTRUMENTS; MILLISECONDS LIVING RADIOISOTOPES; MULTI-NUCLEON TRANSFER REACTIONS; NUCLEAR PHYSICS AND RADIATION PHYSICS; NUCLEAR REACTIONS; NUCLEI; NUCLEOSYNTHESIS; ONE-DIMENSIONAL CALCULATIONS; PHASE TRANSFORMATIONS; PROJECTILES; RADIOISOTOPES; RECOILS; RESIDUES; SILICON 28; SILICON ISOTOPES; SPECTROMETERS; STABLE ISOTOPES; SYNTHESIS; THERMONUCLEAR REACTIONS; TRANSFER REACTIONS; ZIRCONIUM 90; ZIRCONIUM 94; ZIRCONIUM ISOTOPES
• ISSN: 0556-2813; 1089-490X
• DOI: 10.1103/PHYSREVC.81.044610

Fusion excitation functions and angular distributions of evaporation residues (ERs) have been measured for {sup 28}Si+{sup 90,94}Zr systems around the Coulomb barrier using the recoil mass spectrometer, Heavy Ion Reaction Analyzer (HIRA). For both systems, the experimental fusion cross sections are strongly enhanced compared to the predictions of the one-dimensional barrier penetration model (1-d BPM) below the barrier. Coupled channels formalism has been employed to theoretically explain the observed sub-barrier fusion cross section enhancement. The enhancement could be explained by considering the coupling of the low-lying inelastic states of the projectile and target in the {sup 28}Si+{sup 90}Zr system. In the sub-barrier region, the measured fusion cross sections for {sup 28}Si+{sup 94}Zr turned out to be about an order of magnitude higher than the ones for the {sup 28}Si+{sup 90}Zr system, which could not be explained by coupling to inelastic states alone. This observation indicates the importance of multinucleon transfer reaction channels with positive Q values in the sub-barrier fusion cross section enhancement, because {sup 90,94}Zr are believed to have similar collective strengths. This implies that no strong isotopic dependence of fusion cross sections is expected as far as the couplings to collective inelastic states are concerned. In addition, the role of projectile and multiphonon couplings in the enhancement has been explored.