Focusing of an Atomic Beam

TL;DR

This paper demonstrates the use of a bent-crystal gold-mica mirror to focus an atomic helium beam, achieving excellent focusing with potential applications in atomic beam manipulation and microscopy.

Contribution

It introduces a novel bent-crystal mirror technique for focusing atomic beams, with detailed fabrication and performance analysis.

Findings

Achieved effective focusing within the mosaic spread of the surface.

Mirror reflectivity at room temperature is about 10%.

Potential applications include enhanced helium scattering experiments and atomic microscopy.

Abstract

A bent-crystal mirror has been used to focus an atomic helium beam. The mirror is made from gold deposited onto a mica substrate to form a thin film (~5000 {\AA} thick) of large single crystal domains (domain size ~4000 {\AA} ). The mica sheet is then bent in situ to form a cylindrical mirror of variable radius of curvature. Measurement of scattered beam intensity and angular distribution as a function of curvature demonstrate excellent focusing to within the mosaic spread of the surface. The reflectivity of the room temperature mirror is about ten percent. Potential uses are discussed, ranging from immediate applications in intensity and resolution enhancement of helium scattering experiments, to such long term possibilities as hyper-cooling of the beam or fabrication of a scanning atom microscope.