[en] The Ohio University Beam Swinger provides a high resolution, low back-ground time-of-flight facility for the measurement of elastic and inelastic neutron scattering. It has been used to obtain a comprehensive set of differential scattering cross sections for ¹²C, ¹⁴N, ¹⁶O and ⁴⁰Ca between 18 and 26 MeV. The elastic cross sections can be used directly to obtain partial kerma factors and, combined with the known total cross sections, provide accurate values for the reaction cross sections. Angular distributions have been measured for inelastic scattering from all the nuclear levels that cannot decay by particle emission thus providing (by subtraction) a limit on the sum of all charged-particle producing reactions. The integrated cross sections for inelastic scattering from some particle-unstable states in ¹²C are in excellent agreement with the cross sections for three-body breakup obtained by Antolkovic et al. The differential data have been used, together with higher energy proton scattering data to produce energy-dependent optical model parameters for each of these nuclei in the energy range 20-60 MeV. It has been found that the elastic differential cross sections at theta > 100⁰ for ¹²C, ¹⁴N and ¹⁶O cannot be well described by a spherical optical model. Explicit consideration of coupled-channel effects, and in the case of ¹²C, deformation of the ground state, improves the agreement between calculation and experiment. Heavy ion recoil kerma factors and reaction cross sections have been obtained for each element and compared with previous calculations and measurements