NUCLEAR FISSION PROCESS: A STUDY OF THE COMPETITION BETWEEN FISSION AND NEUTRON EMISSION AS A FUNCTION OF EXCITATION ENERGY AND NUCLEAR TYPE

An attempt is made to bring together and correlate all the available information on the probability of heavy elements (with atomic number greater than or equal to 88) to undergo fission when excited to 8 Mev or greater. Due to the nature of the experimental data available, it is necessary to treat the competition between fission and neutron emission rather than simply the probability for fission. The competition between neutron emission and fission is given quantitatively by the ratio of the neutron emission width GAMMA n to the fission width GAMMA /sub F/. Values of this ratio are deduced from all available photo photofission cross sections, fast neutron and chargedparticle induced fission cross sections, and spallation cross sections. Discussion of neutron widths and fission widths derived from resonance energy neutron cross sections are omitted. Correlations of the resulting values of GAMMA n// GAMMA / sub F/ with the liquid drop model fissionability parameter Z/sup 2//A and other possible parameters are investigated. It is of particular interest but also experimentally more difficult to determine the excitation energy dependence of the quantity GAMMA n// GAMMA /sub F/. An attempt is made to draw some qualitative conclusions on this subject from analysis ofmore » fast neutron fission, photofission, and high energy charged particle excitation functions. (auth)« less