Little Manual of the SAXS-beamline


1. BEGINNING OF THE MEASURING SESSION

 

    Checklist:    ! follow carefully point after point !

  1. Switch on the two vacuum pumps at the sample stage and open SLOWLY the two yellow hand valves. At least 10 mbar have to be achieved! For this the valves must be completely opened!
     
  2. Set the X-ray interlock of the experimental hutch.
     
  3. Open valves and shutters using the program RW_BCS1.VI. Therefore, press the OPEN BL button, which then will display "OPEN". Now initiate the process of opening the beamline by activating the program (press "=>" in the upper left corner).

    The valves and shutters open in the following order:
  1. photon shutter 1    ! should be opened first to thermally equilibrate the monochromator !
  2. gate valve 3b        ! can be openend ONLY if you first switched on the vacuum pumps of the experimental station !
  3. gate valve 8 keV    (or 5.4 or 16 keV, if you use that energy)
  4. photon shutter 2    ! this is our secondary beam shutter, thus it can be opened ONLY after the X-ray safety interlock (point 2) is set  !
  5. front end stopper   (see point 4)
  6. front end shutter    (see point 4; common main beam shutter)
  1. Shutters e) and f) can only be opened, if one is set into Experiment. This duty is taken over either by you, or by the Diffraction Beamline, which is underneath the SAXS station (if both parties are present). In case you are the first at the experiment, you should set yourself into Experiment (use the RW_BCS1.VI program) and then open e) and f) as described in point 3. Then you MUST set yourself into Local again.
     
  2. Set the correct fine pitch of the second (upper) monochromator crystal. This is done by adjusting manually the voltage in the range from 0-90 in the program  Piezo-adjust-v22.vi ( subwindow of program Main-Piezo.vi). Further, we strongly recommend to check the fine pitch from time to time in order to stay with the highest possible photon flux.  ATTENTION: you can do this ONLY when the detector is measuring, or if the fast shutter is permanently open !
     
  3. For the detectors check that you allways stay  below the saturation limit (if necessary, you have to insert more aluminum foils to attenuate the beam:
  1. 1D-Gabriel detectors: check that the integral number of counts does not exceed 50 kHz and the countrate per channel does not exceed 1000 Hz !
  2. CCD camera: stay below 65536 (16 bit) cts/ pixel ! 
  3. Image Plate: stay below 65536 (16 bit) cts / pixel !
  4. Pilatus detector: stay below  1 000 000 cts / s / pixel !
ATTENTION: if you switch detector, you also need to select the corresponding fast-shutter connection !




Ultima modifica il Lunedì, 29 Aprile 2019 15:45