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

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, themore » role of projectile and multiphonon couplings in the enhancement has been explored.« less
Authors:
; ; ; ; ; ; ; ;  [1] ; ; ; ; ; ; ;  [2] ;  [3] ; ;  [4] ;  [5]
  1. Department of Physics and Astrophysics, University of Delhi, Delhi-110007 (India)
  2. Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi-110067 (India)
  3. Department of Physics, Calicut University, Calicut-673635 (India)
  4. Department of Physics, Panjab University, Chandigarh-160014 (India)
  5. Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata-700064 (India)
Publication Date:
OSTI Identifier:
21388941
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. C, Nuclear Physics; Journal Volume: 81; Journal Issue: 4; Other Information: DOI: 10.1103/PhysRevC.81.044610; (c) 2010 The American Physical Society
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; ANGULAR DISTRIBUTION; COULOMB FIELD; COUPLED CHANNEL THEORY; COUPLING; EVAPORATION; EXCITATION FUNCTIONS; FORECASTING; HEAVY ION REACTIONS; MASS SPECTROMETERS; MULTI-NUCLEON TRANSFER REACTIONS; ONE-DIMENSIONAL CALCULATIONS; PROJECTILES; RECOILS; RESIDUES; SILICON 28; THERMONUCLEAR REACTIONS; ZIRCONIUM 90; ZIRCONIUM 94 CROSS SECTIONS; DIFFERENTIAL CROSS SECTIONS; DIRECT REACTIONS; DISTRIBUTION; ELECTRIC FIELDS; EVEN-EVEN NUCLEI; FUNCTIONS; INTERMEDIATE MASS NUCLEI; ISOMERIC TRANSITION ISOTOPES; ISOTOPES; LIGHT NUCLEI; MEASURING INSTRUMENTS; MILLISECONDS LIVING RADIOISOTOPES; NUCLEAR REACTIONS; NUCLEI; NUCLEOSYNTHESIS; PHASE TRANSFORMATIONS; RADIOISOTOPES; SILICON ISOTOPES; SPECTROMETERS; STABLE ISOTOPES; SYNTHESIS; TRANSFER REACTIONS; ZIRCONIUM ISOTOPES