Small-angle scattering at a pulsed neutron source: comparison with a steady-state reactor

Abstract

A time-of-flight small-angle diffractometer employing seven tapered collimator elements and a two-dimensional gas proportional counter was successfully utilized to collect small-angle scattering data from a solution sample of the lipid salt cetylpyridinium chloride, C21H38N+.Cl−, at the Argonne National Laboratory prototype pulsed spallation neutron source, ZING-P′. Comparison of the small-angle scattering observed from the same compound at the University of Missouri Research Reactor corroborated the ZING-P′ results. The results are used to compare the neutron flux available from the ZING-P′ source relative to the well characterized University of Missouri source. Calculations based on experimentally determined parameters indicated the time-averaged rate of detected neutrons at the ZING-P′ pulsed spallation source to have been at least 33% higher than the steady-state count rate from the same sample. Differences between time-of-flight techniques and conventional steady-state techniques are discussed.