Differential elastic and inelastic cross sections were measured for 1.5-MeV neutrons scattered by the even-$A$ isotopes of zirconium and molybdenum. The scattering samples were enriched isotopes of ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$, ${}_{}{}^{92}{}_{}{}^{}\mathrm{Zr}$, ${}_{}{}^{94}{}_{}{}^{}\mathrm{Zr}$, ${}_{}{}^{92}{}_{}{}^{}\mathrm{Mo}$, ${}_{}{}^{94}{}_{}{}^{}\mathrm{Mo}$, ${}_{}{}^{96}{}_{}{}^{}\mathrm{Mo}$, and ${}_{}{}^{100}{}_{}{}^{}\mathrm{Mo}$. The cross sections were measured using a dynamically biased neutron time-of-flight spectrometer. The differential cross sections have root-mean-square relative and normalization uncertainties of 2 to 3.5% and 7 to 7.5%, respectively, for elastic scattering, and 6 to 13% and 9 to 15%, respectively, for inelastic scattering. Isotopes with similar level structures have almost identical elastic angular distributions. The entire set of data was theoretically fitted using the optical-statistical model with resonance-width-fluctuation corrections. The calculated elastic differential cross section was assumed to be an incoherent sum of shape-elastic and compound-elastic scattering. At the minima in the angular distributions the cross sections were dominated by compound-elastic scattering.

NUCLEAR REACTIONS ${}_{}{}^{90,92,94}{}_{}{}^{}\mathrm{Zr}$, ${}_{}{}^{92,94,96,100}{}_{}{}^{}\mathrm{Mo}(n,n)$, ($n,n^{\prime }$), $E_n=1.5\mathrm{}$ MeV; measured $\sigma \left(\theta \right)$; deduced optical model parameters. Isotopically enriched samples, neutron time of flight, dynamic bias, compound-elastic scattering, level width fluctuations.

• Received 31 January 1974

DOI:https://doi.org/10.1103/PhysRevC.10.1087