Slow Neutron Velocity Spectrometer Studies. IV. Au, Ag, Br, Fe, Co, Ni, Zn

The spectrometer has been improved, enlarged, and all the operational factors re-evaluated. The principal resonance in gold has been redetermined as $E_0=4.87\mathrm{}\pm 0.07$ ev, and in silver as 5.13±0.07 ev. Resonances are found in Br at 35.7, 54, 104, and 136 ev. Transmission dips are also observed at higher energies which are probably due to unresolved levels. The thermal cross section of iron is well matched by the relation $\sigma =(11.2\mathrm{}\pm 0.33E^{-\frac{1}{2}})$. Crystal interference effects are observed in the thermal region with the Debye-Scherrer rings at 2.3A and 2.8A resolved. The cut-off wavelength predicted to be at 4.04A is in good agreement with experiment. No strong resonances are observed in iron at high energies. Resonances are observed in cobalt at 126 ev and 5000 ev. Ni shows crystal interference effects in the thermal region. No strong resonances were detected at high energies. The thermal cross section of Zn is well matched by the relation $\sigma =3.85\mathrm{}\pm 0.14E^{-\frac{1}{2}}$ with crystal interferences effects observed in the thermal region. Resonances in Zn occur at 520 ev, 1100 ev, and 3800 ev.