Speaker
Description
The OSIRIS backscattering indirect geometry spectrometer at ISIS Neutron and Muon Source is undergoing a major upgrade with the addition of a silicon crystal analyser and position sensitive detectors, complementing the existing graphite analyser and scintillation detectors, respectively. This will extend the accessible timescale from picoseconds to nanoseconds, opening new scientific opportunities in areas such as ionic conductivity in battery materials and slow diffusion processes in solid-state systems. The position sensitivity of detectors will enable to measure momentum transfers in the vertical direction, which will help mostly the single-crystal community with access to full four-dimensional S(Q, ω) spectra.
A central part of the software work involved updating the Instrument Definition File (IDF) — an XML-based description of the instrument geometry that Mantid uses to drive coordinate transformations, detector and pixel grouping, and visualisation across the framework. By adding accurate silicon analyser positions and new parameter files covering energy fixed values and resolution for each silicon reflection, the new analyser became immediately visible in Mantid's Instrument Viewer and correctly handled by the framework's geometry engine without bespoke changes. Building on this, the ISISIndirectEnergyTransfer algorithm and the Indirect Transmission tools were extended to support silicon reflections, with unit and system tests added to cover both analysers.
On the interface side, the prior refactoring of the Indirect Data Reduction GUI into an MVP architecture significantly reduced the cost of adding silicon analyser support: users can now select the silicon analyser and individual reflections directly in the GUI, and both analysers can be run alternately.
This contribution describes the software engineering approach, the design decisions that eased the extension, and lessons relevant to other facilities planning similar instrument upgrades.
