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I11

A high-resolution powder-diffraction 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 I11 (root Asset, tier = Unit, parent_id = None)
Facility Diamond Light Source, the fourth Diamond beamline after I22, I03, and I15-1
Status Design-phase modelling exercise (not a CORA pilot)
Technique high-resolution powder diffraction (often with a temperature ramp)
Beam double-crystal monochromator
Control stack Diamond EPICS (driven by GDA and bluesky)

Design phase, and a deliberate off-roadmap exercise

I11 is a real, operating beamline, but it is not on the CORA pilot roadmap. It is modelled here, like the other Diamond beamlines, 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 I11 earns: a deferred abstraction, banked properly

I11 is the deployment that genuinely earns the abstraction the earlier Diamond beamlines only flirted with. It carries four continuous-setpoint thermal actuators (two Cyberstar hot-air blowers wrapping Eurotherm controllers with set(value)/setpoint/ramprate/PID, and two Oxford cryostreams). After the loose TemperatureController family was carried at I22 and I03, I11 is the rule-of-three that earns:

  1. graduating the TemperatureController catalog Family, and
  2. a new settable-continuous-setpoint actuator Role (CORA had none at the time: Positioner is spatial, Controller supervises, GenericProbe is read-only).

But a new Role is a code change (to cora.equipment.aggregates.role.SEED_ROLES, drift-guarded by an exact-match test) and core cross-facility vocabulary, so it belonged in a separate, gate-reviewed change, not this families-only scaffold. This scaffold carried the four actuators as loose TemperatureController (as I22/I03 did) and TEMP-1 recorded the earn; that gate-reviewed change has since landed, graduating TemperatureController to a catalog Family presenting the new Regulator Role. This is the earn-the-abstraction discipline working: the trigger fires in a deployment, the abstraction is banked deliberately, then graduated under gate-review.

Three other intentional decisions the eval settled, each resisting a mirror-the-controls trap:

  • The diffractometer is per-axis RotaryStage, not the Goniometer Family I03 graduated. theta is a single sample rotation and two_theta/delta are detector-arm angles, not an MX sample-orientation cradle (GONIO-1).
  • The Mythen3 (a 1D position-sensitive strip detector) reuses Camera (Detector Role), with the strip-vs-2D nuance noted; it is skip-flagged in dodal (MYTHEN-1).
  • The sample robot is one Positioner Asset + Clearance + Subject (the locked 19-BM/I03 posture), not a new SampleChanger Family (ROBOT-1).

The beamline

  • Source: the storage-ring state, the double-crystal monochromator, and the beam-defining slits, rendered as the generated source-stage device walk.
  • Sample: the powder diffractometer (sample rotation + detector-arm angles), the capillary spinner, the thermal sample environment, and the sample-changing robot.
  • Detector: the Mythen3 position-sensitive strip detector.

Cutting across:

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

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

Techniques

Techniques: powder diffraction as design intent, often with a temperature ramp over the thermal actuators. A new Capability the catalog does not yet carry (TECH-1).

Governance

Governance: who would act at I11 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 the TemperatureController earn that landed via gate-review.

Not yet documented

I11 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.