Focusing parabolic guide for very small samples

Modern materials can often only be grown in small quantities. Therefore, neutron-scattering experiments are difficult to perform due to the low signal. In order to increase the flux at the sample position, we have developed the concept of a small focusing guide tube with parabolically shaped walls t...

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Bibliographic Details
Published in:Physica. B, Condensed matter Condensed matter, 2004-07, Vol.350 (1), p.166-168
Main Authors: Hils, T, Boeni, P, Stahn, J
Format: Article
Language:English
Subjects:
Ballistic guides
Cross-disciplinary physics: materials science
rheology
Exact sciences and technology
Focusing
Guides
Kumakhov lens
Materials science
Materials testing
Methods of materials testing and analysis
Physics
Supermirrors
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Summary:Modern materials can often only be grown in small quantities. Therefore, neutron-scattering experiments are difficult to perform due to the low signal. In order to increase the flux at the sample position, we have developed the concept of a small focusing guide tube with parabolically shaped walls that are coated with supermirror m=3. The major advantage of parabolic focusing is that the flux maximum occurs not at the exit of the tube. It occurs at the focal point that can be several centimeters away from the exit of the tube. We show that an intensity gain of 6 can easily be obtained. Simulations using the software package McStas demonstrate that gain factors up to more than 50 can be realised on a spot size of approximately 1.2 mm diameter. For PGAA we expect flux gains of up to three orders of magnitude if multiplexing is used. We show that elliptic ballistic guides lead to flux gains of more than 6.
ISSN:0921-4526
1873-2135
DOI:10.1016/j.physb.2004.04.020