Experimental studies of fission barrier properties

A review is presented of the experimental techniques for the determination of fission barrier properties including fission isomer and fission probability measurements. Microscopic statistical models for the extraction of barrier parameter estimates from the experimental data are described. The importance of nuclear symmetry effects on the calculation of fission widths is demonstrated. Evidence is presented for the fragmentation of the mass asymmetric second barrier in the thorium region and the axial asymmetric first barrier in the californium region. Detailed analyses of experimental data suggest the presence of two parallel second barriers; the normal mass asymmetric, axial symmetric barrier and a slightly higher mass symmetric, axial asymmetric barrier. Experimental barrier parameters are determined systematically and compared to calculations from various theoretical models. Techniques for expanding fission probability measurements to higher energies are discussed. (author)