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Focusing Cold neutrons with Multiple Biconcave Lenses for Small-Angle Neutron Scattering Hit : 626

S. M. Choi, J. G. Barker, C. J. Glinka, Y. T. Cheng, and P. L. Gammel

Vol. 33, No. 3-1, 792 - 796, (2000)

 http://dx.doi.org/

Abstract

The focusing of a cold neutron beam by multiple biconcave lenses has recently been proposed as a practical means of extending the lower limit of Q in conventional, long flight-path small-angle neutron scattering (SANS) instruments. To test the feasibility of this approach, we have carried out extensive measurements on one of the 30 m SANS instruments at NIST of the focusing characteristics of a set of 28 biconcave MgF2 lenses. The focused beam profile has been measured over several orders of magnitude using high resolution neutron auto-radiography. The focusing lens configuration outperforms the pinhole collimation at Qmin lower than 0.004 Å-1. At Qmin = 0.001 Å-1, the intensity gain of the lens configuration over the pinhole collimation is greater than one order of magnitude.