Direct experimental estimate of parameters that determine the cascade gamma decay of compound states of heavy nuclei

Abstract

A method is proposed for simultaneously determining the interval of the most probable values of the density of levels excited in the radiative capture of slow neutrons and the sum of radiative E1 and M1 strength functions in the excitation-energy interval extending nearly up to the neutron binding energy. Experimental data on the intensities of two-step photon cascades between the compound state and a given low-lying level of the nucleus being studied are analyzed together with the total radiative widths of neutron resonances. Such an analysis can be performed for nuclei having an arbitrary level density, including deformed ones. The resulting data demonstrate that there are significant deviations from the predictions of commonly accepted level-density models—for example, the Fermi gas model—and specify the range of nuclei and the regions of their excitation energies where a further experimental investigation can furnish new important information about the properties of nuclear matter.