Elastic and inelastic scattering of 1.5-MeV neutrons by the even-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>A</mml:mi></mml:math>isotopes of zirconium and molybdenum

Abstract

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