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The Zebra trigger that gates an XPCS time series, the motion controllers, and the seam between CORA and the floor.

Triggering: the Zebra and the fast shutter

An XPCS measurement is a long, fast train of detector frames under a precisely gated exposure. CHX uses a Zebra FPGA box (Zebra, XF:11IDB-ES{Zebra}:) to gate the fast shutter (OUT1_TTL / SOFT_IN) and the Eiger frame triggers, with a soft-IOC delay generator (delaygen:DG0:) and a fast shutter on the Pel-IO digital-output line alongside. The exact co-timing of the three, and the vendor identities, are a staff question (TIMING-1). This is the same hardware-gated-exposure role the Zebra plays at the other NSLS-II beamlines, here timing a coherent time series rather than a position raster.

Motion controllers

The sample and optics axes are driven by endstation motion controllers whose box models, firmware, and IPs are not in the profile collection (DRIVE-1), so EndstationMotionController is carried as a MotionController family with the specifics blank.

The seam: CORA and the floor

This is where CORA's design meets the CHX floor. The shape matches the other NSLS-II beamlines'.

CORA owns (its conducting engine, over the ControlPort):

  • the XPCS acquisition: arming the Eiger for a long frame series, gating the exposure through the Zebra and fast shutter, and the static SAXS/WAXS and GISAXS acquisitions on the same detectors;
  • the choice of technique, detector, and exposure, gated by the trust boundary.

CORA drives through (the floor it actuates and observes, and does not replace):

  • the EPICS IOCs via the ophyd hardware abstraction: the ControlPort boundary;
  • the Zebra gating, the delay generator and fast shutter, the DCM / DMM drives, the mirror and transfocator feedback, the PSS interlock, and the Eiger / Xspress3 detector IOCs;
  • the facility filestore where the per-run frames land. CORA moves them, over the TransferPort, into CORA's own Dataset of record.

So CORA brings one conducting engine to CHX, working over the ports: XPCS / scattering orchestration over the ControlPort, the correlation analysis (the g2 / multi-tau computation) over the ComputePort, and data egress over the TransferPort into the CORA Dataset. The correlation analysis is a clean ComputePort leg, the coherent-scattering analogue of the reconstruction legs at the imaging beamlines.

The software IOCs (Eiger, Xspress3, Zebra, Prosilica, Scaler, Linkam, the delay generator) are referenced by PV namespace only, never registered as Assets.