MIEZE at FRM II
Research notes on neutron scattering at TUM's research reactor: reduction factor, Monte Carlo, image analysis.
While working at the FRM II research neutron source (TUM, Garching), I built a small site for the research notes I wrote with Lukas Beddrich on the MIEZE technique at the MIRA II three-axis spectrometer.
MIEZE (Modulation of IntEnsity with Zero Effort) is a neutron scattering method for inelastic measurements with very small energy transfers. Because it works like a time-of-flight measurement, the signal is damped by differences in the neutrons' flight paths; that damping is the reduction factor , which should stay as close to 1 as possible. The notes covered:
- Instrument geometry: how the sample, analyser crystal and detector layout affect .
- Reduction factor from images: a bootstrap-inspired algorithm that samples random regions of the detector image.
- Monte Carlo: an efficient Python simulation of where no analytical solution exists, checked against the analytic curves.
- Image analysis of the detector data.
- An interactive calculator on the site: pick the sample shape and method, drag the angles, and the instrument geometry and the reduction-factor curve update live.
The site is still online: read the notes at pabloruizcuevas.github.io. It's built with Vue 3, with KaTeX for the maths.
Photo of the reactor: Forschungs-Neutronenquelle Heinz Maier-Leibnitz by High Contrast, CC BY 3.0 DE, via Wikimedia Commons, cropped.
