I22¶
A small- and wide-angle X-ray scattering (SAXS/WAXS) beamline at Diamond Light Source. This page walks the beamline as it is being modelled; everything here is reverse-engineered from Diamond's open dodal controls library or inferred, not a commissioned measurement.
| Property | Value |
|---|---|
| Asset | I22 (root Asset, tier = Unit, parent_id = None) |
| Facility | Diamond Light Source (bound via facility_code = "diamond", FacilityKind = Site) |
| Status | Design-phase modelling exercise (not a CORA pilot) |
| Techniques | small-angle scattering (SAXS), wide-angle scattering (WAXS), routinely simultaneous |
| Beam | undulator source, double-crystal monochromator, KB focusing mirrors |
| Control stack | Diamond EPICS (driven by GDA and bluesky/blueapi) |
Design phase, and a deliberate off-roadmap exercise
I22 is a real, operating beamline, but it is not on the CORA pilot roadmap (APS to MAX IV). It is modelled here to test two things: that the dry, correct device facts in Diamond's open dodal library can seed CORA's intentional model, and that the model generalizes beyond the tomography pilots. Every value is reverse-engineered from dodal or inferred, carried as confirm until Diamond staff verify it. The things CORA still needs the team to confirm are collected on Open questions.
What makes I22 a different shape from the tomography pilots¶
The CORA pilots (2-BM, and the design-phase 7-BM / 19-BM / 32-ID / TomoWISE) are imaging and tomography beamlines. I22 is a scattering beamline, which stresses the model along an axis the pilots never touched, while sharing most of the equipment.
- A scattering technique, not imaging. SAXS and WAXS record diffraction patterns on area detectors, not projection images of a rotating sample. There is no rotation stage and no tomographic reconstruction. The science Capabilities (small-angle, wide-angle) are new vocabulary the catalog does not yet carry (TECH-1).
- Two detectors, run simultaneously. The routine I22 mode runs a SAXS detector at long camera length and a WAXS detector at short camera length at the same time. They are the same camera model, one Family, two Asset instances separated by distance and role, not a Family split.
- Quantitative flux, not just position. Incident and transmitted ion chambers (I0 / It) read beam current for transmission and dose, presenting the Sensor Role the imaging camera path never needed.
- It carries real EPICS handles. Unlike the TomoWISE scaffold (MAX IV Tango, PVs unknown), dodal records I22's real EPICS PV prefixes. So this scaffold carries
pvon every device: the dry, correct controls fact is the whole point of the exercise.
What I22 does not force into the model: it earns no new catalog Family. dodal's device set maps onto existing Families (Camera, Mirror, Monochromator, InsertionDevice, Slit, BeamStop, LinearStage, TimingController), plus a handful of loose design-intent families an adversarial new-kind review deferred (see Inventory).
The beamline¶
The systems in three areas the beam passes through, plus the controls that drive them. See the beamline overview for how the areas relate.
Along the beam, in order:
- Source: the undulator and the machine-level storage-ring state, the focusing and monochromating optics (the double-crystal monochromator, the KB mirror pair, the adaptive bimorphs, the transfocator), and the beam-defining slits, rendered as the generated source-stage device walk.
- Sample: the experiment hutch, the sample base and on-axis-view camera, the incident and transmitted flux monitors, and the sample-environment actuators.
- Detector: the SAXS and WAXS area detectors that record simultaneously, and the beamstops that protect them.
Cutting across all three:
- Controls: the Diamond EPICS control stack (with the real dodal PV handles) and the PandABox timing and triggering.
The cross-cutting reference view is the Inventory: the planned Asset tree by parent_id with families, the dodal-derived PV handles, and the values still pending confirmation. The Source page is generated from the beamline.yaml descriptor.
Techniques¶
Techniques: what I22 is designed to do, as design intent. SAXS and WAXS are scattering Capabilities the cross-facility Catalog does not yet define; which enter scope is an open question (TECH-1).
Governance¶
Governance: who would act at I22 and the trust shape that gates their commands. People and agents are facility principals at the Diamond Site.
Model¶
Model: the developer's by-kind index into where each CORA aggregate's I22 content lives.
Not yet documented¶
I22 is a modelling exercise for CORA, so the operations runbook (procedures, recipes, cautions) and the live experiment view are deliberately not written: a runbook for an unmodelled, off-roadmap beamline would be invention, not record. The 2-BM deployment shows the shape they would take.