Fabrication and characterization of the source grating for visibility improvement of neutron phase imaging with gratings

Abstract

The fabrication of gratings including metal deposition processes for highly neutron absorbing lines is a critical issue to achieve a good visibility of the grating-based phase imaging system. The source grating for a neutron Talbot-Lau interferometer is an array of Gadolinium (Gd) structures that are generally made by sputtering, photo-lithography, and chemical wet etching. However, it is very challenging to fabricate a Gd structure with sufficient neutron attenuation of approximately more than 20 μm using a conventional metal deposition method because of the slow Gd deposition rate, film stress, high material cost, and so on. In this article, we fabricated the source gratings for neutron Talbot-Lau interferometers by filling the silicon structure with Gadox particles. The new fabrication method allowed us a very stable and efficient way to achieve a much higher Gadox filled structure than a Gd film structure, and is even more suitable for thermal polychromatic neutrons, which are more difficult to stop than cold neutrons. The newly fabricated source gratings were tested at the polychromatic thermal neutron grating interferometer system of HANARO at the Korea Atomic Energy Research Institute, and the visibilities and images from the neutron phase imaging system with the new source gratings were compared with those fabricated by a Gd deposition method.

Photopolymerizable nanocomposite photonic materials and their holographic applications in light and neutron optics

“…Furthermore, multilayer mirrors have also been employed [ 198 ]. Phase and absorption gratings fabricated by photolithographic techniques with periods down to m have found applications in neutron phase imaging [ 199 – 201 ].…”

Neutron Interferometry 2nd Edn

“…Typical parameters for such an arrangement are p 0 = 1.08 mm, p 1 = 7.97 μm, p 2 = 4.00 μm, l = 5.23 m, d = 19.4 mm, w = 20 mm, λ = 4.1(9) Å, and a spatial resolution of the detector of 250μm. The production technique for proper high-resolution gratings is described by Kim et al (2013).…”

Quantitative Neutron Dark-Field Imaging of Milk: A Feasibility Study

“…Each grating has the fabricated-structure area of 100 mm × 100 mm on a 15 cm diameter silicon wafer. G 0 and G 2 were fabricated by a Gadox-particle-filling method [28], and G 1 was fabricated by silicon deep wet etching.…”