Focusing neutrons with a combination of parabolic and elliptical supermirrors

Abstract

Cold-neutron focusing is a challenge with regard to improving the flux at the sample, decreasing measurement time and/or gaining statistical reliability. Several techniques are used for neutron focusing, such as simple or multi-beam collimation, refractive or magnetic lenses, and focusing mirrors. In this work, a new device for focusing neutrons using a combination of a parabolic supermirror, an asymmetric slit system and an elliptical supermirror is presented. The aim of this focusing system is to improve the neutron flux at the sample compared to other techniques without either achromatism or absorption. The performance of the device obtained by simulations and measurements with a prototype on a small-angle neutron scattering setup shows a flux gain of four at the sample position and an intensity gain higher than 100 when the sample size can be increased compared to classical setups. Finally the applications for neutron instruments are commented on.