Simulations of the effect of final state interactions on the scattering reponses of helium droplets

Abstract

We study the effect of final state interactions (FSI) on the scattering responses of Helium droplets. By computing the s-wave component of the one-body density matrix of a Helium droplet, we find strong similarity between bulk Helium and Helium droplets. The edge function of the droplet's s-wave density matrix approaches that of the one-body density matrix of bulk Helium. We compute the scaled dynamic structure factor F =-(qlM) S (q, w) as measured in deep inelastic neutron scattering (DINS) for both bulk Helium and Helium droplets. This is done first without considering the effect of FSI, by applying impulse approximation (IA) to the computation to get FIA. Then we take FSI into consideration. For bulk Helium, F was computed both with and without considering FSI by Carraro and Koonin. They show that FSI broadens the peak in FIA and produces results more in agreement with experimental data. For a Helium droplet, our computation indicates that F with FSI is also broader than FIA. From the similarity between bulk Helium and Helium droplets, along with the results of the study done on bulk Helium, we claim that FSI leads to deviation of the scattering response of a Helium droplet from that predicted by IA even at high momentum transfers, and will be observable in DINS experiments on Helium droplets.