Detector¶
The coherent area detectors, the detector positioner, and the diagnostics. PVs verified against startup/20-area-detectors.py, 10-optics.py, 26-scalers.py, 98-xspress3.py.
CHX's measurement lives on its area detectors. For XPCS the Eiger records a long, fast time series of the coherent speckle pattern; for static scattering it records a single SAXS/WAXS frame. The same detector serves both, the technique is the acquisition, not the hardware.
| Asset | Family | PV | Role |
|---|---|---|---|
Eiger4M |
Camera | XF:11IDB-ES{Det:Eig4M} |
primary XPCS / scattering detector |
Eiger1M |
Camera | XF:11IDB-ES{Det:Eig1M} |
pixel detector |
Eiger500K |
Camera | XF:11IDB-ES{Det:Eig500K} |
pixel detector |
SAXSDetectorStage |
LinearStage | XF:11IDB-ES{Det:SAXS} |
centers the detector transversely on the beam (X/Y) |
SAXSBeamStop |
BeamStop | XF:11IDB-ES{BS:SAXS} |
blocks the direct beam |
FluxCounter |
FluxMonitor | XF:11IDB-ES{Sclr:1} |
I0 normalization |
FluorescenceSpectrometer |
EnergyDispersiveSpectrometer | XF:11IDB-ES{Xsp:1} |
occasional anomalous / element-sensitive |
BeamViewingCamera |
Camera | XF:11IDB-BI{Cam:10} |
on-axis beam-viewing (OAV) |
Centering and the beamstop¶
The SAXSDetectorStage is a transverse X/Y positioner (an XYMotor in source) that centers the area detector on the scattered beam; it does not move along the beam. Whether a separate along-beam stage sets the sample-to-detector distance (and hence the q-range) is not in the public config, so that, and which Eiger is primary, are staff questions (DET-1). The SAXSBeamStop blocks the direct beam ahead of the detector so the weak scattered signal is not swamped.
Reuse, not new vocabulary¶
This is the reinforcement point of CHX as a CORA exercise: a coherence beamline with three area detectors, a detector positioner, and a beamstop that needs no new Family. The Eiger detectors reuse Camera (the Diamond Eiger-to-Camera precedent, also used at SRX); the flux counter reuses FluxMonitor (graduated in #353); the beamstop reuses BeamStop; the occasional fluorescence detector reuses EnergyDispersiveSpectrometer (graduated in #345). The BeamViewingCamera (an on-axis Prosilica OAV; x-ray-eye Prosilicas and a PointGrey serve alignment views) is another Camera. The live set is CAM-1.
The coherent detector chain is the same shape APS 8-ID carries: an area detector under a gated exposure recording a time series. CHX shows it porting to a second facility unchanged.