Techniques¶
What CORA would run at XPD: powder-diffraction and total-scattering techniques, each a Catalog Method. XPD is the NSLS-II twin of the Diamond I11 (powder diffraction) and I15-1 (total scattering / PDF) beamlines, and it follows their deferral exactly.
XPD's techniques are powder diffraction and total scattering, a science domain Diamond's i11 and i15-1 brought to CORA as new Capabilities. As there, the Methods below render unlinked and are carried pending until the owner-scope decision (TECH-1) brings them into the catalog.
| Technique | Mode | Notes |
|---|---|---|
| Powder diffraction | monochromatic, flat panel | Debye-Scherrer rings on the flat panel at a chosen energy; the i11 Capability, new Capability pending (TECH-1) |
| Total scattering / PDF | fixed high energy, close detector | wide-Q on the flat panel at a close detector distance; the i15-1 Capability, new Capability pending (TECH-1) |
| Variable-temperature diffraction | over a temperature ramp | the same, over a ramp on the sample-environment stages (TEMP-1) |
| Autonomous sample exchange | n/a | a Procedure over the spine, threaded through Subject custody and gated by a Clearance (ROBOT-1) |
All the scattering techniques need the diffractometer and sample stages, the flat-panel detectors, and the detector distance; the exposure shutter gates the frames.
Why the Capabilities stay deferred¶
Diamond i11 and i15-1 opened the question of whether the powder-diffraction and total-scattering Capabilities enter CORA's catalog (TECH-1), and main deliberately left them pending: a powder or PDF measurement is a new science Capability binding device Roles that already exist (the flat panel presents Detector, the diffractometer and mono present Positioner), so what is new is the Capability, not a device shape. XPD reinforces the case for both at a second facility without coining either, the same earn-the-abstraction discipline the deferred xpcs (CHX), scanning (HXN), and energy_scan (BMM) Capabilities follow. Because the defining Capabilities are not in the catalog, XPD records no Practice in the NSLS-II Site; the binding lands when the Capability does.
The azimuthal integration and pair-distribution-function reduction (the Fourier transform of the total-scattering structure function into a real-space PDF) are ComputePort work, not beamline Methods. The autonomous sample exchange reuses the i03 / i15-1 autonomous-loop shape: a Procedure over the spine, not a new device family (ROBOT-1).