This webpage should provide you with most information on how to start up the beamline (see LC_Startup webpages) and on recent updates that have occured and any other important news you need to know. We will try to update it regularly, so please feel free to contact the beamline scientist if you feel it's not up to date.

Slits settings (from april 2008):

psvg = 1.0       psvo = 0.0

pshg = 1.0        psho = 0.0

ssvg = 0.8     sshg = 1.0

ssvo = 1.07

ssho = 3.2

 The command "gb_mv_defaults" in Spec(opt) windows should restore  default positions for slits and undulator.

Beamline Usual diode readings (depending slit settings, ring current, diode gain, etc...) with ~ 200 mA in the ring is:

dwb = 1250 cts (diode after the primary slits)

dm2b = 2000-2200  cts (diode after the secondary slits)

I0 = 450 cts (diode after slits in the slit box), with 100 % transmission and s2v = s2h = 0.2.

I1 = 500  cts (diode after the shutter), with 100 % transmission and s2v = s2h = 0.2.

 I0 and I1 are after the attenuators, value is function of the transmission factor and slit settings (s1 and s2). in some cases, I1 can see the light (if the pipe between the slitbox and the diffractometer is away...) from the hutch which create about 200 cts as background; to be rid off, you can switch off the light in the experimental hutch and the sample preparation lab.

How to check the beam position with the motorised scintillator

1- Click on "intrumentation" in mxCuBE
2- Select "Scintillator"; open the "Safety shutter" and the "Fast shutter". A green spot should appear. If not, check if the search has been done in the hutch. The green spot (= the beam) should match the red cross; if not,  click on the "CentreBeam" button (next to the "Beam realign" button) and follow the instructions.

3- Unselect "Scintillator" from the "intrumentation" menu in mxCuBE.

How to check the beam position with the YAG scintillator (if above does not work)

A YAG can be found in the tool box near the entrance door.

Put the YAG screen in place on the PHI axis, put the light in, go to zoom 4 and focus the camera (step size : 0.01 in mxCuBE) to see the surface clearly (the "3 click centering" can be used as well if you have the SMALL YAG screen), put the light off. Open the "Safety shutter" and the "Fast shutter". A green spot should appear. If not, check if the search has been done in the hutch. The green spot (= the beam) should match the red cross; if not, click on the "Centre" button (next to the "Beam realign" button) and follow the instructions. This is important as the three-click centering algorithm uses this position.

If the decoupled beamstop-collimator is installed :

How to align the collimator (not for the G-ring, only with the decoupled collimator-beamstop)

(not in use with G-ring collimator beamstop)

1. no sample on phi axis,
2. search done in the hutch,
3. write down the coly, colz, backz, backy positions on the logbook,
4. "aperture_align" in spec(exp), you should follow the macro in spec(exp), scans are displayed in mxCuBE (thanks Jose!),
5. write down the new coly and colz positions (the calculated positions can be checked from the plots) on the logbook, and check that the backz and backy positions have not been change by the macro.

How to align the backstop (not for the G-ring, only with the decoupled collimator-beamstop)

A macro is being written to automatize this steps of the alignment, but it is not ready now. To align the beamstop, follw the instructions:

1. no sample on phi axis, colimator already aligned, search done in the hutch,
2. write down the coly, colz, backz, backy positions on the logbook. Now you will need to run a set of actions in spec(exp):
   
3. lightin
   
4. lightoff
5. shopen;msopen;transmission 100; plotselect k1;dscan backz -1.5 1.5 60 0.1
   
6. The scan should show a dwell, look where is the middle of the dwell in the plot and move backz (umv backz POSITION) there (it should be near 0);
7. mvr backz 0.175
8. dscan backy -0.6 0.6 30 0.1
9. As for backz, the scan should show a dwell, look where is the middle of the dwell in the plot and move backy (umv backy POSITION) there (it should be near 0.7);
10. mvr backz -0.175; msclose; shclose
    
11. wm coly colz backy backz ===> write the new positions in the logbook
12.  backsavepos A[colz] A[coly] A[backz] A[backy]  (it should update the "beamstop.xml" file with new position).
13. lightout;lighton   (it is important as the light should be turn on to allow crystal visualisation...)
    

It is possible as well to edit the beamstop.xml file which is located in /users/blissadm/local/HardwareRepository/eh2, as blissadm, on sybil.

Experimental table positions lost after a "centrebeam":

You can try to move the table to latest known positions (macro motors) which are:

    thgt ~ 0 (table height)
     ttr ~ 0 (table translation)

In principle, the "0" for the table motor encoders should correspond to the "0" motor position in spec and to the beam at the sample position.