Techniques¶
What the modelled part of IXS is designed to do, as intent. First cut.
A technique is a portable Catalog Method; a Practice is how a facility adapts it. IXS's technique is momentum-resolved hard X-ray inelastic scattering, the fleet's first energy-loss method, so the Method below renders unlinked and is carried pending until a technique enters scope (TECH-1).
Momentum-resolved inelastic X-ray scattering¶
IXS sets the momentum transfer Q with the six-circle reciprocal-space arm, then scans the incident energy against a fixed crystal analyzer and counts the energy-analyzed scattered photons, so the measurement is the intensity surface I(Q, energy-loss): how much energy the sample exchanges with the photon at a chosen momentum transfer. The energy loss is read as the difference between the scanned incident energy and the fixed final energy the analyzer passes.
| Technique | Catalog method | Notes |
|---|---|---|
| Momentum-resolved inelastic X-ray scattering | inelastic_scattering |
Q is set on the six-circle spectrometer arm via the H/K/L reciprocal-space pseudo-axis; the incident energy is scanned on the double-crystal and high-resolution monochromators against the fixed crystal energy analyzer; the energy-analyzed signal is point-counted on the electrometers; Method not yet in catalog |
It needs the incident-energy chain (the DCM for the coarse energy and the high-resolution monochromator for the meV steps), the sample stage, and the six-circle arm, crystal energy analyzer, and counting detectors. The arm scattering angle sets the magnitude of the momentum transfer; the analyzer fixes the final energy so the incident-energy scan reads out the energy loss.
A new operating axis for the fleet¶
Energy loss is genuinely new for the fleet. The catalog already covers elastic scattering (SAXS/WAXS, XPDF, powder, XPCS, MX), XRF microprobe, hard X-ray absorption (BMM), and soft resonant inelastic scattering (SIX), but no hard inelastic scattering. The new axis is the acquisition shape itself: scan one optic (the incident energy) against a second, fixed energy-selecting optic (the crystal analyzer) while a point detector counts, rather than expose an area detector at one energy. That is a new Capability, deferred as a question (TECH-1); it forces no new device families beyond the loose EnergyAnalyzer.
Not modelled yet¶
The concrete acquisition recipes (the incident-energy maps, the per-Q energy scans, the analyzer alignment, and the counting times) are not written yet; they join as the deployment approaches the point where CORA drives IXS. Whether the technique enters CORA's catalog is an owner-scope decision on Model; hard inelastic scattering is a new regime for the fleet (see Open questions for the world-facts to confirm first).