First Excited States inZr92andZr94

Fast neutron inelastic scattering by separated isotopes of Zr was studied by observing the de-excitation gamma-ray spectra. The (926±9)-kev photopeak observed with normal Zr scatters was shown to be produced by two gamma rays differing in energy by less than 2.5% and originating in the isotopes ${\mathrm{Zr}}^{92}$ and ${\mathrm{Zr}}^{94}$. This is interpreted as evidence for a first excited state at about 926 kev in both isotopes. Relative excitation curves for gamma-ray production by neutron inelastic scattering have been measured from threshold to $E_n=5.5\mathrm{}$ Mev for the 850-kev gamma ray from ${\mathrm{Fe}}^{56}$ and the 926-kev gamma rays from ${\mathrm{Zr}}^{92+94}$.