NUCLEAR PHYSICS A ELSEVIER Nuclear Physics A 614 (1997) 238-260 Fusion cross sections for 7Li + 11B and 9Be + 9Be reactions at low energies A. Mukherjee, B. Dasmahapatra Saha Institute of Nuclear Pl~ysics, 1/AF Bidhan Nagar, Calcutta 700064, India Received 9 July 1996; revised 10 October 1996 Abstract The partial cross sections for the 7Li ÷ HB and 9Be + 9Be reactions below and above the Coulomb barrier energy have been determined from the cross sections of the characteristic y-rays of the residual nuclei and using the branching factor o'~/O'ch obtained from the statistical model calculations. The fusion cross sections obtained from the sum of these partial cross sections are found to be equal to the total reaction cross sections upto an energy well above the Coulomb barrier energy for the 9Be ÷ 9Be reaction. For the 7Li ÷ ~B reaction, however, the fusion cross sections are found to be less than the total reaction cross sections at energies not much above the Coulomb barrier. The maximum fusion cross sections for the 7Li ÷ ltB and 9Be + 9Be reactions are found to be 66% and ~ 81% of the total reaction cross sections at Ec.m. = 2Be (where Bc is the Coulomb barrier energy), respectively. PACS: 25.70.Gh; 25.70.Jj Keywords: NUCLEAR REACTIONS llB(TLi, X), Ec.rn. = 1.5-6.8 MeV, 9Be(gBe, X), Ec.m.= 1.3-7.6 MeV; deduced partial, total fusion o'. Statistical model analysis, Optical model calculations. 1. Introduction In a recent article [ 1 ] it has been shown that the fusion cross sections for the 7Li--~-12C and 7Li + 13C reactions at low energies, measured by the detection of the characteristic y-rays of the residual nuclei, are equal to the total reaction cross sections (obtained from the calculations with optical model potential using the parameters from fitting the elastic scattering data) and that there are no limitations of fusion cross sections for these systems at low energies contrary to the measurement by the detection of heavy evaporation residues [2]. This corroborated the work of Scholz et al. [3] who also did not find any limitation of fusion cross sections for the 7Li + 160 reaction at low energies 0375-9474/97/$17.00 Copyright (~) 1997 Elsevier Science B.V. All rights reserved. PH S0375-9474(96)00447-2