Quasi-specular albedo of cold neutrons from powder of nanoparticles

TL;DR

This paper reports the first observation of quasi-specular neutron reflection from nanoparticle powders, showing that cold neutrons can be reflected at small angles with significant probability due to multiple scattering.

Contribution

It introduces the concept of quasi-specular albedo for cold neutrons from nanoparticle powders and provides experimental evidence for this phenomenon.

Findings

Reflection probability ~30% at small angles

Reflection angle matches incidence angle

Angular distribution width is approximately equal to incidence angle

Abstract

We predicted and observed for the first time the quasi-specular albedo of cold neutrons at small incidence angles from a powder of nanoparticles. This albedo (reflection) is due to multiple neutron small-angle scattering. The reflection angle as well as the half-width of angular distribution of reflected neutrons is approximately equal to the incidence angle. The measured reflection probability was equal to ~30% within the detector angular size that corresponds to 40-50% total calculated probability of quasi-specular reflection.