From x-ray telescopes to neutron focusing

Abstract

In the case of neutrons the refractive index is slightly less than unity for most elements and their isotopes. Consequently, thermal and cold neutrons can be reflected from smooth surfaces at grazing-incidence angles. Hence, the optical technologies developed for x-ray astronomy can be applied for neutron focusing. The focusing capabilities of grazing incidence neutron imaging optics have been successfully demonstrated using nickel mirrors. The mirrors were fabricated using an electroformed nickel replication process at Marshall Space Flight Center. Results of the neutron optics experiments will be presented. Challenges of the neutron imaging optics as well as possible applications of the optics will be discussed.

Demonstration of a novel focusing small-angle neutron scattering instrument equipped with axisymmetric mirrors

“…10 are made of only natural Ni. Supermirror Wolter optics is technologically possible, 24 but it is not necessary for SANS in most cases. Wolter optics for SANS could be designed and made within months for a fraction of a cost of a SANS instrument, using standard ray tracing and proven technology.…”

Demonstration of achromatic cold-neutron microscope utilizing axisymmetric focusing mirrors

“…To work around this limitation and dramatically improve the performance of mirror-based instruments, we have used optical designs and technology inspired by x-ray telescopes. 1,[23][24][25][26][27] This paper reports the demonstration of a prototype cold-neutron microscope, which is equipped with image-forming Wolter mirrors. Images of test samples, such as those in Figure 1, were taken and analyzed.…”

“…The signal rate is improved by increasing both the effective source area and the solid angle of the collected beam. When the optics is well optimized, including the use of nested coaxial confocal mirrors and high-critical-angle coating, 23 enhancements of orders of magnitude in signal rates could be possible. 1,35,36 In addition to the signal rate, the field of view 37,38 and depth of focus also require optimization of the mirrors' geometry.…”