Large Scales - Long Times: Adding High Energy Resolution to SANS

TL;DR

This paper proposes a novel SANS instrument design combining MIEZE and TOF techniques at ESS, enabling high energy resolution measurements of depolarizing and magnetic samples over microsecond timescales with low cost.

Contribution

It introduces a new instrument concept integrating MIEZE and TISANE for enhanced SANS measurements at high energy resolution.

Findings

Design case for ESS instrument demonstrating feasibility

Ability to study magnetic and depolarizing samples in detail

Maintains low cost and effort for high-resolution measurements

Abstract

The Neutron Spin Echo (NSE) variant MIEZE (Modulation of IntEnsity by Zero Effort), where all beam manipulations are performed before the sample position, offers the possibility to perform low background SANS measurements in strong magnetic fields and depolarising samples. However, MIEZE is sensitive to differences \DeltaL in the length of neutron flight paths through the instrument and the sample. In this article, we discuss the major influence of \DeltaL on contrast reduction of MIEZE measurements and its minimisation. Finally we present a design case for enhancing a small-angle neutron scattering (SANS) instrument at the planned European Spallation Source (ESS) in Lund, Sweden, using a combination of MIEZE and other TOF options, such as TISANE offering time windows from ns to minutes. The proposed instrument allows studying fluctuations in depolarizing samples, samples exposed to strong magnetic fields, and spin-incoherently scattering samples in a straightforward way up to time scales of \mus at momentum transfers up to 0.01 {\AA}-1, while keeping the instrumental effort and costs low.