Study of Thin Iron Films for Polarization Analysis of Ultracold Neutrons

TL;DR

This study investigates thin iron films on different substrates to evaluate their suitability as polarization analyzers for ultracold neutrons in neutron electric dipole moment experiments.

Contribution

It provides characterization data of thin iron films on aluminum and silicon substrates, demonstrating their potential for use in UCN polarization analysis for nEDM measurements.

Findings

Iron films on aluminum saturate at ~12 kA/m

Iron films on silicon saturate at 6.4 kA/m

Neutron reflectometry estimates a 2 T magnetic potential for Si substrate films

Abstract

The TUCAN (TRIUMF Ultra-Cold Advanced Neutron) collaboration aims to search for the neutron electric dipole moment (nEDM) with unprecedented precision. One of the essential elements for the nEDM measurement is a polarization analyzer of ultracold neutrons (UCNs), whose main component is a magnetized thin iron film. Several thin iron films were deposited on aluminum and silicon ubstrates and were characterized by vibrating sample magnetometry and cold-neutron reflectometry. A magnetic field required to saturate the iron film is $\sim$12 kA/m for those on the aluminum substrates and 6.4 kA/m for the silicon substrates. The magnetic potential of the iron films on the Si substrate was estimated to be 2 T by the neutron reflectometry, which is sufficient performance for an UCN polarization analyzer of the nEDM measurement.