Theory of the radiative width of a highly excited nucleus

A microscopic theory of the electromagnetic radiation emitted by a highly excited nucleus is developed on the basis of the Landau theory of a Fermi liquid. Closed formulae are obtained for the mean radiative width and its mean square fluctuation from level to level. The temperatures of many nuclei are found from the observed widths. The relaxation time is estimated from the experimental data on the radiative-width fluctuations. The regions of applicability of the various types of relations between the relaxation time and the lifetime of the compound nucleus, as well as the relevant physical consequences, are discussed.