Anomaly in Energy Level Density Measurements

An analysis of nuclear reactions in the intermediate energy range has been made in terms of the statistical theory of nuclear reactions using the Fermi gas level density, $\mathrm{const}\times \exp \left[{\mathrm{}\left(\mathrm{aE}\right)\mathrm{}}^{\frac{1}{2}}\right]$, where $E$ is the energy of excitation. The quantity, $a$, determined from excitation function experiments and from the ($\alpha , p$) reaction at 40 Mev shows an anomalous behavior when plotted against atomic number, $A$. On the other hand, the values of $a$ determined from several inelastic scattering and reaction experiments show the correct dependence on $A$. The effects of noncompound-nucleus processes are discussed.