Polarization and Differential Cross Section of Neutrons Scattered fromBe9: Parities of the 7.37- and 7.54-MeV States inBe10

The polarization and the differential scattering cross sections for neutrons scattered from ${\mathrm{Be}}^9$ were measured at 5 angles for neutron energies from 0.2 to 2.0 MeV. The data are interpreted in terms of a two-channel process. The neutron scattering resonances at 0.625 and 0.815 MeV, corresponding to levels in ${\mathrm{Be}}^{10}$ at 7.37 and 7.54 MeV, were assigned the spin and parity values $J^{\pi }=3^{-} \mathrm{}(l=2\mathrm{})\mathrm{}$ and $J^{\pi }=2^{+} \mathrm{}(l=1\mathrm{})\mathrm{}$, respectively. The calculations took account of the effects of $s$-wave and $p$-wave backgrounds as well as approximate contributions of $1^{-}$ and $2^{-}$ bound states.