This is a detailed description of the BCS control system as far as it is being used by a general user of beamline 12.2.2.
Main Window:
(1) Schematic of beamline components
The main body of the entry Window depicts a schematic of the beamline from the monochromator (outside the hutch) all the way to the I1 ion chamber at end-station1 inside the hutch.
I1: This is the Ion chamber measuring the X-ray flux coming through the Slits
Slit: These are the slits set around the position of the primary focus of the X-ray beam. The X-ray beam moves in the plane of the slits (i.e. perpendicular to the beam direction), when it gets out of focus.
We can therefore use the flux through these slits to retune the focus. See M2 2:1 Toroid and Double Xtal Mono)
- Fast Shutter: This is a fast shutter that allows timing of exposures downstream of this position. The icon is active; when you click on it, you can open or close the Fast Shutter. Note that on ACQ you have a direct open/close toggle to control the Fast Shutter.
- Filter Box: This is a box containing 4 sets of X-ray filters allowing to attenuate the X-ray beam if needed. It is mostly used when doing single crystal diffraction. The icon is active; when you click on it you can change the filter settings.
- BPM: Obsolete
- PSS: This refers to the Personal Safety Shutter. It shows its status only and cannot be controlled here. It is controlled either with the button on the rack above your head or from the EPS system.
- M2 2:1 Toroid: This icon represents the M2 primary focus mirror. It has fixed toroidal groove and a dynamically bendable long radius. The bends are set by BL scientists and are rarely touched. The tilt (pitch) of the mirror relative to the incoming X-ray beam determines the focus point along the X-ray direction and is optimized by the BL staff at the beginning of a cycle. Since it also moves the X-ray beam in the vertical direction, it can be easily retuned by users by maximizing the photon flux through the Slits. This can be done through a automatic routine that is accessed from the Tune Window. To open the Tune Window click on the M2 icon.
- I Mono Out: This is a thin Al foil that acts as a X-ray diode to probe the tuning of the monochromator's rocking curve.
- Double Xtal Mono: This icon represents the monochromator. The beamline has a Si(111) and a Multi-Layer (ML) monochromator. The Si(111) has a resolution ΔE/E of about 10000, the ML's resolution is about 100. Consequently, the ML has about 2 orders of magnitude more flux. The energy range of the Si(111) is between ~ 8 keV and ~ 35 keV. The ML's energy range is restricted to ~ 12 keV to ~ 25 keV. Changing from Si(111) crystal to ML requires BL staff assistance. Changing energy and tuning the two crystals onto each other can be done by the users. To do this, follow these instructions.
- I Mono In: This is an aperture defining the incident beam onto the first crystal of the monochromator. It also acts as a diode and allows us to monitor whether there is beam on the monochromator at all. Normal values at 500 mA storage ring current and sufficient time for thermal equilibration are around 100 nA.
(2) Menu
File: As a user you will not need this
AI: As a user you will not need this
DIO: As a user you will not need this
Beamline: As a user you will not need this
Logging: As a user you will not need this
Windows: As a user you will not need this