Automatic Edge Scans
last modified
22-10-2009 15:40
- The automatic edge scans are working quite robustly and generally should not cause problems.
- NOTE - The automatic edge scans will now also try to move the undulators automatically or give a relevant message
- However it is always good to first check the undulator settings on the machine status window before starting to make sure that the U24.4 is either set to 19.2 mm (maximum intensity side-stations), 17.2 mm for Se, 21.2 mm for Br, 16.01 mm for As, Pt, Hg, W, or 18.7 mm for Pb. You have to change the gap if it is different from these numbers. Always inform the users of the other side stations, especially ID14-3 (BioSAXS station) before changing the undulators, since this might effect their measurements. Advise them to do a quick-realign afterwards. Change the undulators only when really necessary.
- Select Energy scans in mxCuBE and click on the element in the periodic to select the element of interest. Do Scan. You now have to wait !
- Did the macro stop before doing the energy scan? This probably means that it could not find a proper attenuation factor. Check i) the beam intensity - storage ring, front-end, interlock, undulator settings, etc- and ii) whether the flouresence detector was moved in.
- Did the macro stop during the energy scan? Sometimes the mono does not feel happy. Just redo the scan, until you see the peak and the inflection point.
- Did you interrupt the scan? Perhaps double check that the sample is still in the beam, e.g. by looking in mxCuBE.
- Is the fluorescent scan very noisy? Make sure that the fluorescent detector is well aligned underneath the sample! If it was, then it probably means that too much attenuation was used. Use less attenuation. Type in the following command in the EH4-spec session: mcaguion, mcaon, mattset N (N = smaller number than the one given in mxCuBE), shopen, msopen, monoscan E1 E2 100 1 (E1 and E2 are an energy 0.05 keV below and above the edge, and are given in keV), mcaoff, msclose, shclose.
- Scan is completely flat. Note down your observation in the logbook, and redo the scan.
- You cannot find your edge. Ask you LC, (preferable in advance), to help to do it by hand if your edge is supported at all.
- Click here for instructions on the manual operation.
The macro will try to find the correct attenuation for the MCA, starting with the strongest attenuation in order to prevent unnecessary exposure of your precious sample. Provided that it found a setting that gave enough counts on the MCA, it will set the MCA parameters correctly, move the energy and will do the scan and displays the counter roic.
What can go wrong?