Techniques¶
What the modelled part of LIX is designed to do, as intent. First cut.
A technique is a portable Catalog Method; a Practice is how a facility adapts it. LIX measures biological structure three ways: biological solution scattering (bio-SAXS / WAXS), in-line size-exclusion-chromatography-coupled scattering (SEC-SAXS), and scanning-microbeam mapping of cells and tissue. The Methods below render unlinked and are carried pending until the owner-scope decision (TECH-1) brings any of them into the catalog.
| Technique | Catalog method | Notes |
|---|---|---|
| Biological solution scattering (bio-SAXS / WAXS) | solution_scattering |
small- and wide-angle scattering from a protein in solution in the flow cell, read on the SAXS Pilatus 1M; the fleet's first solution-scattering Method, new to the catalog (TECH-1) |
| In-line SEC-SAXS | solution_scattering |
the HPLC delivery pump flows an eluting size-exclusion peak through the cell while the SAXS detector reads; the same solution_scattering Method with the chromatographic elution as the acquisition axis (TECH-1, FLUID-1) |
| Scanning-microbeam mapping | scanning_fluorescence_microscopy |
raster the microbeam across a cell or tissue section on the scanning goniometer, reading scattering and fluorescence per point; reuses the existing pending Method (TECH-1) |
All three techniques need the incident-beam chain (the undulator and DCM for energy, the mirrors and transfocator for focus, the slits), the sample side (the positioning stack or scanning goniometer, and for the solution modes the fluidic delivery chain), and the endstation detectors (the Pilatus heads, beamstop, flux monitors).
Where the novelty is: the Subject, not the Method¶
LIX's measurement, small- and wide-angle X-ray scattering, is a science axis the fleet already speaks. The materials-scattering beamlines SMI, CMS, Diamond I22, and APS 9-ID / 12-ID-E all run small- and wide-angle scattering on the same Camera / FluxMonitor / BeamStop vocabulary. So the scattering hardware and detection are reinforcement, not novelty.
What LIX adds is a new Subject and a new sample-delivery shape, not a new detector. The specimen is a protein in solution rather than a solid mount, and for SEC-SAXS it is an eluting chromatographic peak whose elution profile is the acquisition axis. That is why solution_scattering is proposed as a Method distinct from the materials small_angle_scattering: not because the optics differ, but because the Subject and the acquisition (a flowing, time-resolved liquid correlated to chromatography) differ. Whether the catalog ultimately holds one scattering Capability with solution-versus-solid as a Practice adaptation, or a distinct solution_scattering Capability, is the owner-scope decision (TECH-1); LIX records the case, it does not mint the vocabulary.
The matching Site Practices (LIX_solution_scattering_practice, LIX_sec_saxs_practice, LIX_microbeam_scanning_practice) are carried pending in the NSLS-II Site; each binding lands when its Capability does.
SEC-SAXS is a Procedure over the fluidic seam¶
In-line SEC-SAXS is the technique that most exercises the fluidic delivery chain, and CORA models it as a Procedure, not a new device. The run equilibrates the size-exclusion column, injects the sample, and reads SAXS frames continuously while the peak elutes through the flow cell. The actuators it drives, the HPLC delivery pump (a FlowController) and the selector valves (the seam), are conducted over the ControlPort; the column and buffers are Supply; the eluting peak is a Subject; the frames correlated to the elution are the Dataset. The technique's identity in CORA's record lives in the Subject, Supply, and Procedure, not in a device or a new detector (FLUID-1, SEC-1, SUBJECT-1).
Not modelled yet¶
The concrete acquisition recipes are not written yet. For solution scattering that is the per-frame exposures, the buffer-subtraction sequence, and the azimuthal integration that turns 2D frames into I(Q) curves (the integration and reduction are ComputePort work, not beamline Methods). For SEC-SAXS it is the column-equilibration and injection steps, the flow program, and the peak-fraction model that maps frames to elution. For the scanning mode it is the raster trajectory and the per-point reduction. These join as the deployment approaches the point where CORA drives LIX.
Whether any of these techniques enters CORA's catalog is an owner-scope decision on Model: a modelling exercise reinforces the case but does not mint cross-facility Method vocabulary on its own. See Open questions for the world-facts to confirm first.