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last update 15/02/2010
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 Beamline procedures 

Operating procedures
Open and close the beamline
Alignment of the beamline
Alignment of the refocusing optics 		  Maintenance / Emergency
Monochromator optimisation
Configuring Heidenhain encoders
Recovery from a powercut
BCS restart
Ion pumps

ALIGNMENT OF THE BEAMLINE

  1. Start BCS Java.



  2. Do not open the beamline! Check out that the double slit is not wide open (could happen after FEL shift) and also the position of the switching mirror chamber.

  3. Go to double slit → motion control menu. The position read by the potentiometer must be as follows:

    UP = 1.1 mm
    DOWN = 2.1 mm
    LEFT = 2.7 mm
    RIGHT = 3.8 mm


  4. Go to double slit → slit width. Check that the settings are:

    Vertical Gap = 3.20 mm
    Horizontal Gap = 6.50 mm


  5. Go to switching mirror → chamber position menu. For the left branchline the settings are:

    Horizontal Position = -25.70 mm
    Vertical Position = -18.30 mm


  6. It's time to select the grating in the monochromator cage. Make sure that the grating chosen in BCS Java is actually the one that is inserted. Go to Monocromator → Corrected Energy Scan and select the appropriate grating. Grating #1 (i.e. VLS 200) is the low energy (200 lines/mm), and grating #2 (VLS 400) is the high energy one (400 lines/mm).

  7. Insert the diode after exit slit. The IN value is 47 mm, as noted on the linear feedthrough. Make sure that the amplifier is not in x100 mode. (In fact start with x1 setting to be on the safe side).

  8. Back to the "BCSJava", Set the energy to the desired value. Also set the undulator gap, phase, and modulator current to the corresponding values, which can be obtained from the "utilities" drop-down menu.

  9. When the beam is available (Check under "Insertion Device → Ring Status"), open the beamline ("BCSJava" → "utilities" → "valve manager"). Select the "Quick open" button. This will open everything except the SHUTTER, STOPPER, and the last valve before the speleem chamber. These valves have to be opened manually.

  10. Open the STOPPER and SHUTTER. Keep an eye on the pressure in the double slit section. It will rise to mid 10-7 mbar range. Wait before opening the valve to the SPELEEM.

  11. Using (in BCS Java) the diode after exit slit reading, scan the monochromator (corrected) energy around the expected undulator peak. Once the can is completed, set the energy to the maximum of the undulator peak in order to proceed with the alignment.

  12. While the SPELEEM valve is closed, insert the diode after refoc.mirror. This is on the same linear feedthrough as the mesh, and its positionis marked. The signal output from this photodiode is fed to the same amplifier as the diode after exit slit, so switch the BNC input connector on the amplifier nearby.

  13. Make sure the SPELEEM Main Chamber pressure is at least in the 10-9 mbar range. If so, open the valve. In order to avoid damaging the microscope MCP detector, turn off the SPELEEM high voltage.

  14. Please connect the cable coming from the diode after exit refocussing to the input of the (remember that this signal diode after refoc.mirror.

  15. Go to "switching mirror → berger drivers", select the diode after exit slit and check the "manual scan graph" box.

  16. Optimize the switching mirror horizontal pos, pitch, and roll in order. Most likely, a few iterations are needed to reach a stable maximum in the photodiode signal.

  17. When the signal is optimized on the diode after refoc.mirror, close the SPELEEM valve, move the mesh into place. Note that the when the beamline is optimized, the ratio between the readings of the two photodiodes should be around 3.