Detector¶
The SAXS / WAXS / MAXS area detectors, the detector translations and telescoping flight path, the beamstop, the flux monitors, the beam-position monitor, and the specular reflectivity mechanism. Reverse-engineered from NSLS2/cms-profile-collection (startup/*.py); PVs read from the profile collection, carried confirm.
CMS's measurement is the scattering pattern on a Pilatus area detector, read at the small-, wide-, or medium-angle position down a telescoping flight path. The same detector face also carries specular X-ray reflectivity, with no extra hardware: the reflected beam is tracked across the fixed Pilatus by a software region as the sample angle is stepped. Every device on the detection side binds an existing catalog Family, and reflectivity is a Method over them, so this page coins nothing.
Detection chain¶
| Device | Family | PV | Role |
|---|---|---|---|
SaxsDetector |
Camera |
XF:11BMB-ES{Det:PIL2M} |
Pilatus 2M, small-angle (SAXS); also the detector for specular reflectivity (DET-1, XR-1) |
WaxsDetector |
Camera |
XF:11BMB-ES{Det:PIL800K} |
Pilatus 800K, wide-angle (WAXS) (DET-1) |
MaxsDetector |
Camera |
XF:11BMB-ES{Det:PIL800K2} |
a second Pilatus 800K at the medium-angle position; one 800K head is powered at a time per configuration (DET-1) |
DetectorStage |
LinearStage |
the SAXS / WAXS / MAXS detector translations and the telescoping flight path | sets the sample-to-detector distance and hence the accessible angle; distances are calibration (DET-1) |
Beamstop |
BeamStop |
XF:11BMB-ES{BS:SAXS} |
blocks the SAXS direct beam (DET-1) |
EndstationFluxMonitor |
FluxMonitor |
ion chamber IM:3 + BIM4 scintillation counter IM:4 + endstation electrometer IM:2 |
incident-flux measurement at the endstation for normalization (DET-1) |
BeamPositionMonitor |
BeamPositionMonitor (loose) |
XF:11BMB-BI{BPM:1} |
BIM5 four-quadrant diamond-diode beam-position monitor (DIAG-1) |
The chain reads outward from the sample. The Pilatus area detector records the scattering pattern; the detector stage translates it along the telescoping flight path to set the sample-to-detector distance, which is what selects the angular range a run covers. The beamstop blocks the direct beam off the SAXS detector face. The endstation flux monitors read the incident flux as a scalar for normalization, drawing on the ion chamber, the BIM4 scintillation counter, and the endstation electrometer together. The diamond-diode beam-position monitor reads the four-quadrant beam position for diagnostics.
CMS carries three Pilatus heads across the small-, wide-, and medium-angle positions, but only one 800K head is powered at a time per configuration (DET-1): the WAXS and MAXS positions share that constraint, so the active geometry is a setting on the configuration rather than three independent live cameras. Detector distances are calibration values, carried as settings on the stage and not invented here (DET-1).
Specular reflectivity without a two-theta arm¶
Specular X-ray reflectivity (XR) is the one genuinely distinct measurement on the detection side, and it is realized with no new hardware. There is no physical two-theta detector arm and no point detector. The area detector stays fixed, and the "two-theta" is synthetic: a software region-of-interest slides across the fixed Pilatus face to where the reflected beam lands as the sample theta (the sth axis on the SampleGoniometer, see Sample) is stepped. The specular intensity for each step is the integrated counts inside that tracked region; the reflectivity curve is built by stepping sth and reading the moving region across the stationary detector (XR-1).
This means XR composes only devices that already exist for scattering:
| Role in XR | Device | Family |
|---|---|---|
| the swept angle | SampleGoniometer sth |
Goniometer |
| the detected signal | SaxsDetector read over a tracked region |
Camera |
| incident normalization | EndstationFluxMonitor |
FluxMonitor |
No device is coined, no two-theta arm is modelled, and no point detector is added (XR-1). The reflectivity Method is shared with i10, its soft X-ray RASOR sibling; CMS is the second consumer of that Method, the first to realize it on a hard X-ray area detector by sliding a region across the fixed Pilatus rather than swinging a detector (XR-1, TECH-1). The integrated-region readout and the sth step list are calibration and run settings, carried not invented.
Why no new detector family¶
The detection side reinforces the catalog rather than extending it. The three Pilatus heads reuse Camera; the detector translations and flight path reuse LinearStage; the SAXS beamstop reuses BeamStop; the endstation flux monitors reuse FluxMonitor. The only loose binding is the BeamPositionMonitor Family for the BIM5 diamond-diode BPM, and that Family is already held under review across the fleet (4-ID, 8-ID, 9-ID) pending the sensor fold-versus-promote decision; CMS adds a sighting, not a new Family (DIAG-1).
XR adds no detector family either, because it is a Method over the same Goniometer + Camera + FluxMonitor vocabulary, not a device. CMS's SAXS / WAXS / MAXS scattering overlaps the fleet heavily: it is the direct NSLS-II twin of SMI and shares its science axis with Diamond I22 and APS 9-ID / 12-ID-E, reusing the same Camera / Goniometer / Slit / BeamStop / FluxMonitor vocabulary with zero new families. That scattering side is reinforcement, not novelty. What is distinct here is the hard X-ray reflectivity Method realized with no new hardware (XR-1), and CMS standing up as a further NSLS-II beamline re-testing the Site and Federation kernel.
Families¶
Reused from the catalog: Camera (the three Pilatus heads), LinearStage (the detector translations and telescoping flight path), BeamStop (the SAXS beamstop), and FluxMonitor (the endstation ion chamber, scintillation counter, and electrometer). Loose and held under review: BeamPositionMonitor (the BIM5 diamond-diode BPM, DIAG-1). New families: none; nothing graduates and the catalog is unchanged. Specular reflectivity is the reflectivity Method over Goniometer + Camera + FluxMonitor, the second consumer after i10 (XR-1, TECH-1). The one-800K-at-a-time configuration and the detector-distance calibration are DET-1. See Inventory for the Asset tree, Model for the family decisions, and beamline.md for the source walk.