Blank images

Blank images

Are the images completely white? If so it is likely that you restarted the detector without taking a dark current. Repeat the data collection and 'force a dark current' in the pop-up window in MxCuBE. If the problem persists then it is a detector specific problem. Try restarting the detector software (see detector solutions page). However if you do see just grey images with no back-stop shadow then your crystals has not seen the X-ray beam. First check 'Front End' to ensure there is current and the 'Front End' is open. Then check to make sure that the ID14-4 optics hutch is interlocked and that the safety shutter is open. You can do this in the MxControl GUI or by typing 'shopen' in the OH2 SPEC session (orange window  in the 'Expert desktop' on right screen of artemis2). Then check that all the valves in the 'XVacuum' application are open (or green). If they are white, they click on the valve and a pop-up window will appear and allow you to open or close the valve. If there is a vacuum problem then the safety mechanism will stop you from doing this. In this case check the vacuum readings, they should all be below <1 x e-8, the valves are set to cut off around 1 x e-6.  Here the hall operator (ext 2525) maybe able to help.   

Another easy check is to simply open the 'safety shutter' in MxCuBE. If there is some beam the i0 flux value (displayed on the right panel in mxCuBE hutch tab) should give a value of >2 x e11. The absolute value is dependent on many factor, attenuation, slit size, energy (related to undulator gaps) and the source current etc. A typical value at 13.2 keV is 4.4 x e12 with 200mA ring current. If the beam is off a little it is often worth checking this with larger slit values (0.5 - 1.0 mm). If there is a little beam (~ 1 x e11) then the easiest thing to do is a 'Quick realign'. If this is all ok, then perhaps the 'fast shutter' is not opening. In this case you need to open the 'fast shutter' in mxCuBE and do a 'ct' in 'EXP' SPEC session (blue window in 'Expert desktop'). The flux_i1 (the diode after the shutter) should give a value a similar to flux_i0. If these are <1 x e10 then there is probably no beam. It is also a good idea to visually check the beam with a YAG screen. If there is no beam with the beamstop out then the problem maybe be up-stream. See 'Beam viewers' section to check this. Other possibilities to check out are: 1) The piezo fast shutter control box. In the case of an electrical blip the protect light can go from green to orange. If it is orange then click this switch 'off' and 'on' and retry with the YAG. 2) Perhaps try restarting the MUSST synchronization card and doing a reconfig in SPEC (EH4). 3) Try restarting SPEC (EH4) from scratch (by doing an 'eh4 -f on lidd144 as opid14).