Small-Angle X-Ray Scattering from Liquid Helium I and Liquid Helium II

X-rays from a rotating Cu anode x-ray tube have been scattered from liquid helium at angles up to 5 degrees in the temperature range from 1.5°K to 4.2°K. The helium was contained in a thin-walled aluminum tube enclosed in a metal cryostat with beryllium windows. The liquid structure factor obtained experimentally, agreed well with the theoretical zero-angle liquid structure factor between 3°K and 4.2°K. Below about 2°K, the observed value of the zero-angle structure factor is larger than the theoretical value by an amount believed to be outside the experimental error. Angular distributions at 4.2°K are typical of liquid scattering patterns near the critical point. No scattering anomaly was observed near the $\lambda$ point.