Total Neutron Cross Sections of Compounds with Different Crystalline Structures

The total neutron cross sections of polycrystalline compounds, such as close-packed hexagonal ZnO, body-centered cubic T1Br, and face-centered cubic CaO and TiC were determined with the Argonne neutron velocity selector and neutron crystal spectrometer in the energy region of 0.001 to 1.0 electron volt. From the size of the cross-section peaks which are due to coherent scattering of neutrons the following scattering amplitudes were determined: Ca, +0.46×${10}^{-12\mathrm{}}$ cm; Ti, -0.25×${10}^{-12\mathrm{}}$ cm; T1, +0.75×${10}^{-12\mathrm{}}$ cm. The previously reported value of +0.58×${10}^{-12\mathrm{}}$ cm for Zn was confirmed. The free atom scattering cross section of Ca is 2.5 barns.