Measurement of fusion excitation functions of Al-27,Al-29,Al-31+Au-197

A systematic study of the sub-barrier fusion reactions with neutron-rich pr ojectiles has been carried out for three isotopes Al-27,Al-29,Al-31 bombard ing a Au-197 target. A target chamber equipped with a target stack and sets of MWPC was employed in order to enhance the efficiency of the radioactive beam experiment. Coupled-channel calculations including the quadrupole exc itations do not well fit the measured fusion excitation functions, whereas flat barrier distributions to represent the coupling to the neutron transfe r largely account for the observed enhancement of the sub-barrier fusion cr oss-sections.