Neutron-induced opalescence in silica glass

TL;DR

This paper investigates neutron-induced opalescence in silica glass by analyzing light scattering during fiber irradiation in a nuclear reactor, revealing a novel scattering effect similar to critical opalescence.

Contribution

It introduces the concept of neutron-induced opalescence (NIO) and links it to changes in Rayleigh scattering coefficient during neutron irradiation.

Findings

RSC increase during fast-neutron irradiation resembles critical opalescence.

OTDR traces reveal two components: RIA and RSC variation.

Neutron irradiation causes a measurable increase in scattering akin to opalescence.

Abstract

Light scattering intensity distribution along the optical fiber length is analyzed, which was measured by optical time domain reflectometry (OTDR) during and after fiber irradiation in a nuclear reactor. The OTDR traces prove to contain two components associated with either radiation-induced attenuation (RIA), or with Rayleigh scattering coefficient (RSC) variation. The RSC increase effect in the first stage of fast-neutron irradiation is argued to be similar to the anomalous scattering buildup near the critical point of the liquid-vapor transition known as critical opalescence. For his reason, the RSC increase due to fast-neutron irradiation can be named neutron-induced opalescence (NIO).