IXS

The momentum-resolved hard X-ray Inelastic X-ray Scattering beamline at NSLS-II, and CORA's first hard inelastic-scattering deployment. This page walks the operational core CORA models today. It is a reverse-engineered first cut, not yet a running model.

Property	Value
Asset	IXS (root Asset, tier = Unit, parent_id = None)
Facility	NSLS-II (bound via facility_code = "nsls2", FacilityKind = Site)
Sector	Sector 10 (PV namespace XF:10ID*; not a registered Asset)
Status	First cut, reverse-engineered, design-phase (descriptor + docs; scenarios deferred)
Source	An in-vacuum undulator (IVU22) on the SR:C10-ID straight
Control stack	NSLS-II EPICS / ophyd (the same floor as FXI / HXN / BMM / SRX / SIX / CHX); handles bound from the profile collection, carried confirm

First cut, and confirm-pending by intent

This scaffold was reverse-engineered from the beamline's own bluesky profile collection (NSLS2/ixs-profile-collection). EPICS PVs are real and verified against the startup/*.py files; vendor part numbers, serials, and physical positions are not in the profile collection and are open questions. Every value is carried as confirm until IXS staff verify it. What CORA needs the team to confirm is on Open questions.

What makes IXS different

IXS is CORA's first hard inelastic-scattering beamline, the first photon-in / photon-out energy-LOSS technique in the fleet. The deployments before it cover elastic scattering (SAXS/WAXS, XPDF, powder, XPCS, MX), XRF microprobe, hard X-ray absorption (BMM), and soft resonant inelastic scattering (SIX), but no hard inelastic scattering. What is new is the acquisition shape: set the momentum transfer Q with a six-circle reciprocal-space pseudo-axis, then scan the incident energy against a fixed crystal analyzer, point-detecting the energy-analyzed scattered beam to build I(Q, energy-loss). meV resolution comes from a high-resolution monochromator plus a temperature-stabilized diced crystal analyzer.

The acquisition has three moving parts:

• Set Q. A six-circle scattering arm (tth / th / chi / phi) driven by an H/K/L reciprocal-space pseudo-axis places the detector at the scattering angle that selects the momentum transfer.
• Scan incident energy. The Si(111) double-crystal monochromator (DCM) and the high-resolution monochromator (HRM2) step the incident energy in meV steps while the analyzed final energy stays fixed; energy transfer is the difference.
• Point-detect against a fixed analyzer. A diced crystal energy analyzer Bragg-reflects the scattered beam to a fixed final energy and focuses the energy-selected photons onto quad electrometers, normalized by an I0 scaler. Detection is point / current-integrating, not an area detector.

Almost every device reuses an existing catalog or loose Family. IXS introduces one device class new to the catalog, the crystal energy analyzer, modelled as a loose family at n=1 (nothing graduated):

• A diced crystal energy analyzer. The signature instrument is a diced multi-crystal Bragg analyzer (six diced crystals, each with orientation and PID temperature stabilization) that selects a fixed final photon energy of the scattered beam and focuses energy-selected photons onto the point detectors. No catalog Family fits this anatomy, so it binds a loose EnergyAnalyzer Family, the <Quantity>Analyzer sibling of 4-ID's loose PolarizationAnalyzer (see Model).

Everything else (the undulator, the DCM and HRM2 crystal monochromators, the mirrors, the slits, the transfocator, the six-circle arm, the temperature controller, the electrometers) reuses an existing catalog or loose Family.

Scope: what is and is not modelled

Part	In this cut	Why
Optics (XF:10IDA/B/C)	Yes	The DCM, HRM2, the transfocator, the mirrors, the slits, the secondary source aperture, the transport table
IXS endstation (XF:10IDD)	Yes	The KB mirrors, the sample stages, the six-circle spectrometer arm, the crystal analyzer, the counting detectors
New device classes	Loose at n=1	EnergyAnalyzer: held loose, nothing graduated (see Model)
The six-circle arm	Catalog Goniometer	The 8-ID / 4-ID diffractometer anatomy, not SIX's dispersive SpectrometerArm (see Model)
The analyzer-plus-arm Assembly	No	Deferred as 8-ID / 4-ID deferred their diffractometer Assemblies (ANALYZER-1)
The simulated devices and legacy SPEC macros	No	A scaffold provenance, not modelled here
Integration scenarios + vendor Models	No	Design-phase; the descriptor and docs come first

The deferred parts are recorded on Model.

Key modelling decisions

• Reuse over coin. Every device but the energy analyzer binds an existing catalog or loose Family, and the catalog changes nothing. The crystal energy analyzer is the only class no Family covers, and it stays loose at n=1: a second independent hard crystal-analyzer beamline must earn the abstraction before any catalog change.
• The six-circle arm binds the catalog Goniometer. The scattering arm driven by the reciprocal-space pseudo-axis is the 8-ID / 4-ID six-circle diffractometer anatomy, not SIX's energy-dispersive SpectrometerArm (a different, dispersive instrument). In descriptor mode it binds Goniometer directly.
• The analyzer Assembly is named, not built (ANALYZER-1). Whether the crystal analyzer plus the six-circle arm compose an Assembly(Diffractometer)-style Fixture is deferred, exactly as 8-ID and 4-ID deferred materializing theirs. The first cut is a flat loose EnergyAnalyzer Asset plus a Goniometer arm Asset.

The beamline

• Source: the generated device walk: the undulator, the front-end slit and transfocator, the DCM and HRM2 and their slits and beam-position monitors, the transport optics, the KB refocusing mirrors, and the endstation optics.
• Sample: the sample positioning table and the sample-environment translations.
• Detector: the six-circle spectrometer arm and its reciprocal-space pseudo-axis, the crystal energy analyzer and its thermal stabilization, and the counting electrometers and I0 scaler.

Cutting across them:

• Controls: the EPICS / ophyd control stack and the bluesky-orchestration seam; handles bound from the profile collection and carried confirm.

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

Techniques

Techniques: what the modelled part of IXS is designed to do, as intent. Momentum-resolved hard X-ray inelastic scattering is new to CORA's catalog and renders unlinked, carried pending (TECH-1).

Governance

Governance: who will act at IXS and the trust shape that gates their commands. People and agents are facility principals at the NSLS-II Site.

Model

Model: the developer's by-kind index, the new loose family this deployment introduces, and the record of what is deliberately deferred.

Not yet documented

IXS is not yet driven by CORA, so the operations runbook and the live experiment view are deliberately not written yet. They join as the deployment firms up. The 2-BM deployment shows the shape they will take. The PSS search-and-secure permit signals and shutters are absent from the profile collection and are not invented here (PSS-1).