Magnetic compound refractive lens for focusing and polarizing cold neutron beams

Biconcave cylindrical lenses are used to focus beams of x rays or neutrons using the refractive properties of matter. In the case of neutrons, the refractive properties of magnetic induction can similarly focus and simultaneously polarize the neutron beam without the concomitant attenuation of matte...

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Bibliographic Details
Published in:Review of scientific instruments 2007-03, Vol.78 (3), p.035101-035101-8
Main Authors: Littrell, K. C., te Velthuis, S. G. E., Felcher, G. P., Park, S., Kirby, B. J., Fitzsimmons, M. R.
Format: Article
Language:English
Subjects:
COLD NEUTRONS
CYLINDRICAL CONFIGURATION
FOCUSING
GEOMETRY
LENSES
NEUTRON BEAMS
PARTICLE ACCELERATORS
PERMANENT MAGNETS
POLARIZED BEAMS
REFRACTIVE INDEX
SMALL ANGLE SCATTERING
X RADIATION
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Summary:Biconcave cylindrical lenses are used to focus beams of x rays or neutrons using the refractive properties of matter. In the case of neutrons, the refractive properties of magnetic induction can similarly focus and simultaneously polarize the neutron beam without the concomitant attenuation of matter. This concept of a magnetic refractive lens was tested using a compound lens consisting of 99 pairs of cylindrical permanent magnets. The assembly successfully focused the intensity of a white beam of cold neutrons of one spin state at the detector, while defocusing the other. This experiment confirmed that a lens of this nature may boost the intensity locally by almost an order of magnitude and create a polarized beam. An estimate of the performance of a more practically dimensioned device suitable for incorporation in reflectometers and slit-geometry small angle scattering instruments is given.
ISSN:0034-6748
1089-7623
DOI:10.1063/1.2709844