Performance of an elliptically tapered neutron guide

• Published in: Physica. B, Condensed matter Condensed matter, 2006-11, Vol.385, p.1247-1249
• Main Authors: Mühlbauer, Sebastian, Stadlbauer, Martin, Böni, Peter, Schanzer, Christan, Stahn, Jochen, Filges, Uwe
• Format: Article
• Language: English
• Subjects: Ballistic neutron guides; Elliptically tapered neutron guides; Exact sciences and technology; Focusing neutron optics; McStas simulations; Neutron physics; Nuclear engineering and nuclear power studies; Nuclear physics; Physics; Supermirrors
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/j.physb.2006.05.421

Supermirror coated neutron guides are used at all modern neutron sources for transporting neutrons over large distances. In order to reduce the transmission losses due to multiple internal reflection of neutrons, ballistic neutron guides with linear tapering have been proposed and realized. However, these systems suffer from an inhomogeneous illumination of the sample. Moreover, the flux decreases significantly with increasing distance from the exit of the neutron guide. We propose using elliptically tapered guides that provide a more homogeneous phase space at the sample position as well as a focusing at the sample. Moreover, the design of the guide system is simplified because ellipses are simply defined by their long and short axes. In order to prove the concept we have manufactured a doubly focusing guide and investigated its properties with neutrons. The experiments show that the predicted gains using the program package McStas are realized. We discuss several applications of elliptic guides in various fields of neutron physics.