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I15-1

An X-ray pair-distribution-function / total-scattering (XPDF) 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 I15-1 (root Asset, tier = Unit, parent_id = None)
Facility Diamond Light Source (bound via facility_code = "diamond"), the third Diamond beamline after I22 and I03
Status Design-phase modelling exercise (not a CORA pilot)
Technique total scattering / pair distribution function (PDF)
Beam bent-Laue monochromator (fixed-energy selection), multilayer mirror
Control stack Diamond EPICS (driven by GDA and bluesky)

Design phase, and a deliberate off-roadmap exercise

I15-1 is a real, operating beamline, but it is not on the CORA pilot roadmap. It is modelled here, like I22 and I03, to test the dodal-seed pipeline against another technique. Every value is reverse-engineered from dodal or inferred, carried as confirm until Diamond staff verify it. See Open questions.

What I15-1 earns: nothing new (and that is the point)

I15-1 was chosen partly on the expectation that it would graduate the open settable-actuator affordance. A close read of the dodal source refuted that. Like I22, I15-1 earns zero new catalog Families and zero new affordances: every device maps onto an existing Family or a reused loose one. Its value is consolidation plus three intentional-modelling decisions, each of which resists a mirror-the-controls trap:

  • SafeOrBeamPositioner is a Positioner, not a new affordance. The blower / cobra / cryostream sample-environment devices are each a Movable that drives a motor to two named positions, SAFE and BEAM. That is the existing Positioner Role with Indexable named positions, not a settable-actuator affordance, and not a TemperatureController: the dodal classes are named for temperature controllers but model only the in/out-of-beam move, so modelling them as TemperatureController would mirror the class name, not the behaviour (SAFEBEAM-1).
  • The rail is a Table, not a new Rail Family. The shared support on which the cobra and cryostream are interchanged is the existing Table Family (the TomoWISE DetectorGantry precedent), not a coined kind (RAIL-1).
  • The interlocks are not devices. The PSS and goniometer interlocks dodal exposes are the data behind the Enclosure permit_signal (the shipped Enclosure aggregate), so they are carried on the enclosures, not as equipment Assets (INTERLOCK-1).

It also reuses FluxMonitor for the incident-flux monitor (the JBPM TetrAMM i0), the deployment that completed its rule-of-three graduation into the catalog, and adds a third robot-as-Positioner instance (after I03 and 19-BM).

The beamline

Along the beam, in order:

  • Source: the storage-ring state, the bent-Laue monochromator (fixed-energy, a y-to-energy lookup readback, not a scanning DCM), the multilayer mirror, the attenuators, the beam-defining slits and shutters, rendered as the generated source-stage device walk.
  • Sample: the sample positioning and hexapod, the two-theta detector arm, and the interchangeable sample-environment devices on a shared rail, plus the powder/capillary sample-changing robot.
  • Detector: the Eiger area detector capturing wide-Q total-scattering frames, a second detector translation, and the incident-flux monitor.

Cutting across all three:

  • Controls: the Diamond EPICS control stack (with the real dodal PV handles) and the Zebra timing.

The cross-cutting reference view is the Inventory. The Source page is generated from the beamline.yaml descriptor.

Techniques

Techniques: total scattering / PDF as design intent. The total-scattering Capability is new vocabulary the catalog does not yet carry; the energy-scan Capability is explicitly not earnable here (the bent-Laue mono is a fixed selection, not a scan) (TECH-1, ENERGY-1).

Governance

Governance: who would act at I15-1 and the trust shape, including the Clearance that would gate autonomous robot loading. Principals are facility-wide at the Diamond Site.

Model

Model: the developer's by-kind index, and why I15-1 adds no catalog kinds.

Not yet documented

I15-1 is a modelling exercise, so the operations runbook and the live experiment view are deliberately not written. The 2-BM deployment shows the shape they would take.