Employing (n, n′γ) reactions to exclude nuclear levels erroneously introduced in other investigations: On the 3 1 − level in 56Fe

Abstract

Reactions of the (n, n′γ) type proceed through a compound-nucleus stage; therefore, the excitation cross section is usually independent of the level nature. Accordingly, all of the excited states must manifest themselves in such reactions through γ transitions (with allowance for their internal conversion). In comparing the energy-level and γ-transition diagrams obtained in investigating γ rays from the inelastic scattering of fast reactor neutrons with the diagrams published in the last issues of Nuclear Data Sheets, it was found that 120 levels in 34 nuclei must be excluded from compiled data because the γ transitions expected from them were not observed. The case of the questionable first 31− level in 56Fe at 3076 keV is considered by way of example. It is concluded that there is no such level in 56Fe.