Detector¶
The detectors that make ISS an absorption + emission beamline. PVs verified against the iss-profile-collection startup files.
Which detector is read decides the measurement: the ion chambers for transmission EXAFS, the silicon-drift array for fluorescence EXAFS, and the crystal emission spectrometers for XES and HERFD.
| Asset | Family | PV | Technique it serves |
|---|---|---|---|
IonChambers |
FluxMonitor | XF:08IDB-CT{Amp-I0} |
transmission EXAFS (I0 / It / Ir / If) |
FluorescenceDetector |
EnergyDispersiveSpectrometer | XF:08IDB-ES{Xsp:1}: |
fluorescence EXAFS (Xspress3 SDD) |
AreaDetector |
Camera | XF:08IDB-ES{Det:PIL1}: |
emission-spectrometer focus / 2D patterns |
JohannSpectrometer |
EmissionSpectrometer | XF:08IDB-OP{HRS:1} |
XES / HERFD (back-scattering) |
VonHamosSpectrometer |
EmissionSpectrometer | XF:08IDB-OP{MC:3-Ax} |
XES (wavelength-dispersive) |
Absorption detectors¶
The IonChambers are the I0 / It / Ir / If transmission and reference chambers, read through configurable amplifiers (the in-house ICAmplifier at XF:08IDB-CT{Amp-I0 / It / Ir / If} and, currently, Keithley 428 preamps at XF:08ID-ES:{K428}:A-D:) and digitized synchronously by the analog pizza box during the fly-scan; they reuse FluxMonitor (graduated in #353). The FluorescenceDetector is a four-channel Xspress3 silicon-drift array (XF:08IDB-ES{Xsp:1}: channels C1-C4) for fluorescence EXAFS, reusing EnergyDispersiveSpectrometer. The exact channel-to-chamber map and Xspress3 element count are DET-1.
The emission spectrometers: a graduation¶
The signature ISS instruments are two crystal emission spectrometers. The JohannSpectrometer is a Rowland-circle back-scattering analyzer composing a main crystal plus four auxiliary crystals (XF:08IDB-OP{HRS:1-Stk:1-5}) on a two-theta detector arm (XF:08IDB-OP{HRS:1-Det:Gon:Theta1 / Theta2}), for high-energy-resolution XES and HERFD. The VonHamosSpectrometer is a wavelength-dispersive analyzer (XF:08IDB-OP{MC:3-Ax}, sharing the detector arm) that spreads the emitted spectrum onto the AreaDetector (a Pilatus 100k, reusing Camera).
Both bind the EmissionSpectrometer family that LCLS-MFX introduced for its von Hamos XES spectrometer. ISS is the second sighting of that family, so it earned the rule-of-three; the abstraction is settled (a crystal-analyzer emission spectrometer is a distinct, recurring device, not a point Sensor and not a beam-conditioning Monochromator), so it GRADUATED into the catalog (SPEC-1), LCLS-MFX's references swept alongside. Whether each of the Johann's analyzer crystals is a child Asset or a setting is the residual SPEC-1 question. It stays distinct from the still-loose EnergyAnalyzer (the IXS diced-crystal energy-selecting analyzer) and SpectrometerArm (the SIX grating RIXS arm).