Sample¶
The endstation XAFS stages: the sample table, the batch sample wheel, and the reference-foil holder. PVs verified against startup/BMM/user_ns/motors.py.
BMM is built for throughput: many samples mounted on a wheel, each indexed into the beam and scanned in turn, with a reference foil measured alongside for energy calibration.
| Asset | Family | PV | Role |
|---|---|---|---|
SampleStage |
LinearStage | XF:06BM-ES{MC:09} |
sample positioning table (x, y, pitch, roll) |
SampleWheel |
RotaryStage | XF:06BMA-BI{XAFS-Ax:RotB} |
rotating wheel indexing many samples |
ReferenceHolder |
LinearStage | XF:06BMA-BI{XAFS-Ax:RefX} |
reference-foil holder for energy calibration |
The sample wheel and the sample-changer question¶
The SampleWheel reuses the RotaryStage Family: physically it is a rotation axis, and the "wheel of N samples indexed through the beam" is batch automation, a Method/conduct concern, not a new device kind. This is the conservative call at first sighting.
But BMM is not the only deployment with sample-exchange automation: the Diamond MX beamlines (i03) carry a robotic sample changer (family-less, presenting the Positioner Role). Whether a dedicated sample-changer abstraction is earned across the BMM wheel and the Diamond robots, or each stays its underlying motion Family, is the open question (WHEEL-1). CORA defers it here rather than minting a SampleWheel or SampleChanger Family at one sighting.
The reference foil in ReferenceHolder is what the Ir ion chamber reads (see Detector): a known standard measured in every scan so the energy axis can be calibrated against its known edge.