Measurements of neutron fields in a wide energy range using multi-foil activation analysis

TL;DR

This paper demonstrates the use of multi-foil activation analysis combined with Bayesian unfolding to accurately measure neutron flux and energy spectra across a wide range at spallation sources.

Contribution

It introduces a comprehensive method for neutron field characterization using multi-foil activation and Bayesian analysis at spallation sources.

Findings

Effective measurement of neutron flux across thermal to 100 MeV energies.

High precision and accuracy achieved in neutron spectrum unfolding.

Validated technique on ISIS spallation source beamlines.

Abstract

An accurate characterization of the neutron fields at spallation sources is crucial for many applications based on neutron irradiations, such as radiation damage tests that need a precise dose estimate. In this work we present the neutron flux measurements performed with the multi-foil activation technique in the ROTAX and ChipIr beamlines of the ISIS spallation source, characterized by moderated and unmoderated spectra, respectively. We selected many different activation reactions to cover a wide energy range, from thermal to very fast neutrons up to about 100 MeV. By applying a Bayesian unfolding algorithm, we demonstrate the effectiveness of this technique in measuring the neutron flux intensity and energy spectrum with precision and accuracy.