A study of the transition from gaslike to liquidlike behaviour expected in supercritical Ar

We propose a neutron diffraction study of supercritical fluid Ar at 300 K to accurately measure the Frenkel line transition in this system. The study will be the first where the Frenkel line is characterized using diffraction data to high Q for a spherically symmetric system. It will play a key role in our general understanding of the Frenkel line transition in the supercritical region by adding to the small body of reliable data in the literature on this topic. The study will also provide essential preliminary data for our planned studies of supercritical fluid mixtures.Separately, it allows us to systematically compare the effectiveness of different analysis methods for diffraction data from fluids and amorphous solids, resolving current controversy in this topic.We therefore expect two high quality publications from this beamtime.