Development of a Fresnel lens for cold neutrons based on neutron refractive optics

We have developed compound refractive lenses (CRLs) fur cold neutrons, whic h are made of vitreous silica and have an effective potential of (90.1-2.7 x 10(-4)i) neV. In the case of compound refractive optics, neutron absorpti on by the material deteriorates lens performance. Thus, to prevent an incre ase in neutron absorption with increasing beam size, we have developed Fres nel lenses using the electrolytic in-process dressing grinding technique. T he lens characteristics were carefully investigated with experimental and n umerical simulation studies. The lenses functioned as a neutron focusing le ns, and the focal length of 14 m was obtained with a 44-element series of t he Fresnel lenses for 10 Angstrom neutrons. Moreover, good neutron transmis sion of 0.65 for 15 Angstrom neutrons was obtained due to the shape effect. According to comprehensive analysis of the obtained results, it is possibl e to realize a CRL for practical use by choosing 3 suitable lens shape and material. (C) 2001 Elsevier Science B.V. All rights reserved.