A review on fusion barrier measurements for heavy and super-heavy systems

Heavy element synthesis through heavy-ion induced fusion reaction is an active field in contemporary nuclear physics. Exact knowledge of fusion barrier is one of the essential parameters for planning any experiments for heavy element production. Theoretically there are many models available for prediction of the exact barrier. Though these models are successful for predicting the fusion of medium mass nuclei, it somehow fails for predicting the exact location of barrier for fusion of heavy nuclei. Experimental determination of barrier for such reactions is required for future experiments for the synthesis of heavy elements. Traditionally fusion barrier is determined by taking a double derivative of fusion excitation function. However, such method is difficult in case of fusion of heavy nuclei due to its very low fusion/capture cross section and its experimental complications. Alternatively fusion barrier can be determined by measuring the quasi-elastic cross section at backward angles. This method can be applied for determining the fusion barrier for the fusion of heavy nuclei. In my talk I start with a detail review for experimental determination of fusion barrier by different methods and compare the fusion excitation function and quasi-elastic scattering methods for the determination of fusion barrier and present a status of such measurements for heavy systems in different lab. At IUAC, New Delhi recently a programme has been started for the measurement of fusion barrier through quasi-elastic scattering methods. I shall present the experimental facility and the first few results of the experiments carried out with this facility. (author)