Fluctuations of Nuclear Cross Sections in the "Continuum" Region

Abstract

An examination was made of the nontrivial consequences of the statistical assumption in the continuum region in which a larger number of compound states overlap because of the short lifetime of the compound nucleus. It is shows that the proper statistical prediction for experiments performed with good energy resolution in the incident beam is that partial cross sections and angular distributions fluctuate even though a large number of intermediate states are excited, the formation and decay of the compound nucleus are independent only on the average, and the fluctuations can be used to determine the lifetime of the compound nucleus in the continuum region. It is generally concluded that the excitation of a large number of intermediate compound states automatically implies that cross sections are smooth functions of the energy and that angular distributions are symmetrical around 90 deg to the beam direction. (B.O.G.)