Peculiarities of neutron waveguides with thin Gd layer

TL;DR

This paper investigates neutron wave behavior in structures with thin gadolinium layers, revealing a poisoning effect analogous to reactor physics, and demonstrates significant neutron density enhancement useful for studying magnetic domain formation.

Contribution

It introduces the phenomenon of neutron poisoning in Gd layers and shows how neutron density can be significantly enhanced in Nb/Gd structures both theoretically and experimentally.

Findings

Poisoning effect analogous to reactor physics identified.

Neutron density enhancement of an order of magnitude achieved.

Potential to study domain formation in Gd layers under superconducting transition.

Abstract

Peculiarities of the formation of a neutron enhanced standing wave in the structure with a thin highly absorbing layer of gadolinium are considered in the article. An analogue of the poisoning effect well known in reactor physics was found. The effect is stronger for the Nb/Gd/Nb system. Despite of this effect, for a Nb/Gd bilayer and a Nb/Gd/Nb trilayer placed between Al2O3 substrate and Cu layer, it is shown theoretically and experimentally that one order of magnitude enhancement of neutron density is possible in the vicinity of the Gd layer. This enhancement makes it possible to study domain formation in the Gd layer under transition of the Nb layer(s) into the superconducting state (cryptoferromagnetic phase).