Corrective polishing of a shaper-cut metallic-ellipsoidal neutron focusing mirror

Abstract

An increasing number of neutron focusing mirrors are being adopted in neutron scattering experiments in order to provide high fluxes at sample positions, reduce measurement time and/or increase statistical reliability. To realize a small focusing spot and high beam intensity, mirrors with both high form accuracy and low surface roughness are required. To achieve this, a fine polishing method, in which the material is removed effectively without losing profile accuracy, is developed to reduce the surface roughness of the mirror. High form accuracy in the major-axis is obtained through corrective polishing, and low surface roughness is acquired under a low polishing load. As a result, an ellipsoidal neutron focusing mirror is successfully fabricated with high form accuracy of 0.5 μm peak-to-valley (PV) and low surface roughness of 0.2 nm root-mean-square (rms).