Time-of-flight implementation of an ultrasmall-angle neutron scattering instrument

We report calculations describing the Bonse-Hart ultra-small-angle neutron scattering (USANS) instrument with triple-bounce Si channel-cut crystals, which show that significant gains in Q-resolution and neutron flux can be achieved using multiple high-order Bragg reflections. These reflections become usable only after combining the Bonse-Hart and time-of-flight (t-o-f) techniques, thus this variant of the USANS camera needs a pulsed neutron source. We demonstrate that t-o-f USANS instruments installed, for example, at the SNS water moderator will improve the current state of the art. Through the use of multiple wavelengths, these will provide means to detect multiple scattering effects.