Krist, T. ; Teichert, A. ; Kovacs-Mezei, R. ; Rosta, L.: Neutron supermirror development. In: Erko, A. [u.a.] [Eds.] : Modern developments in X-ray and neutron opticsBerlin: Springer, 2008 (Springer series in optical sciences ; 137). - ISBN 978-3-540-74560-0, p. 355-370
Abstract:
Supermirrors are aperiodic multilayers of two materials, which allow reflecting neutrons at small grazing angles. They are used mainly for the transport of neutrons through guides or for polarization. The first part of the article describes the improvements of Ni-Ti supermirrors for guides in the Budapest laboratories, which were achieved by relating the crystalline structure of supermirrors to their reflectivity. Furthermore the behavior of supermirrors under heat load and irradiation was characterized and the homogeneity of the coating process improved. This made it possible to produce Ni-Ti supermirrors with m=4. In the second part from the Berlin laboratory the polarization of neutrons is introduced and several methods to prepare polarized neutron beams are described with the emphasis on polarizing supermirrors. They reflect only one spin component and transmit the other one. The main challenge today is to increase the number of layers, which requires improved interfaces between the layers and reduced stress in the layers. In the last years the number of layers was increased from 150 to 1000 and the m-value from m=2.3 to m=3.4.