Pop_up scintillator up and mxCuBE says it is down.

Write apout in spec(exp) (it shopuld move down the YAG) or YAG_STATE="in" in spec(exp) (it will reset mxCuBE info).

 

Pop_up scintillator down and mxCuBE says it is up.

Write YAG_STATE="out" in spec(exp).

 

 No intensity after a "Beam Realign"

After a quick realign, you observed that there is little or no intensity. You should check the slit positions in the "Exes Control Panel" application (normally on "plotting" desktop or start with the "Start Expert Control Panel" icon on the desktop of sybil). The usual values should be around:

secondary slits: ssvg = 0.8 sshg = 1  ; ssvo = 1.0 ssho = 3.0

primary slits: psvg = 1.0 pshg = 1.0 ; psvo = 0.0 psho = 0.0

slit box: s1v = s1h = 0.4 ; s2v = s2h =  0.35

U20 = 11.50 (undulator setting)

 

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

 

The expected 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 = 2400-2600 cts (diode after the secondary slits)

I0 = 500 cts @200 mA (diode after slits in the slit box), with 100 % transmission

I1 = 550cts @200 mA (diode after the shutter), with 100 % transmission.

I0 and I1 are after the attenuators and their value is therefore a function of the transmission factor and slit settings (s1 and s2).

 

Beam seems to be very unstable.

It is time to have look at the curves displayed on the large screen! The top line (monochromatic beam) and the white beam line should have the same features or variations and be as "parallel" as possible. The decay should follow the ring decay.

1- Check on the large screen (on the longer wall of the cabin) how the dark pink line is (it reads and plots the intensity of the white beam after the primary slits). If you see important variations at that level, phone the control room (24-90) to check if they observe as well beam instabilities at the ID23 ring section.

2- It could be linked with monochromator instabilities. You should see on the large screen that the monochromatic beam intensity is no more following the white beam intensity. You can check that the temperature of the monochromator motor is stable or not (see the top temperature displayed on EXES-Control Panel on sybil; the temperature is usually around 0 oC). Variation of 0.1 to 0.2 are normal, more not. If it is the case, check the motor control card (DPAP2 type, motor is name theta and the card is located on the electronic rack near the optic hutch main door) which should be on "alarm" (red led) as the power should be switch off when the motor is not in use (99.9 % of the time). If all the led of the DPAP card are green, you can do a "reconfig" in spec(opt) and ~10 s after the current should be switch off. Then let's wait that the temperature drop down to the nominal value and follow the beam with the "centrebem" button.

 

High background scatter near the beamstop

Before realigning the beamstop, check the s2v and s2h positions (vertical and horizontal gap) which should be around 0.3 for both. If not, move them to 0.3, take a new diffraction image to assess the quality. If they is still plenty of background (more than 1000 cts per pixel on the MarCCD application) then you can try to realign the beamstop.

It seems that the crystal is not hit by the beam.

I assume there is beam...

Check if the crystal is well centred on the "red cross". If not do a quick "3 click centering" and take a diffraction pattern with, as starting angle for the data collection, the phi position where you are certain that your crystal is centred (PHI motor in the GUI).  If there is still no diffraction, either your crystal is not diffracting or the red cross is not aligned with beam (but nonetheless you should often see a beam mark in the cryoprotectant where the beam did hit) in which case you have to put back the scintillator and to realign the beam to the phi axis: go to the "Instrumentation" menu, click on the "Scintillator" button, if the beam is not on the red cross, click on "centre beam" (top right of mxCuBE), click the Scintillator button again to move away the scintillator and collect a new diffraction pattern. You can also check the beam position with the normal YAG that you can mount on the phi axis which will allow you to focus properly the beam on the video camera (better).

Detector distance is lost

For some reasons, you have the feeling that the detector distance (dtox) is wrong and you wish to reset it (as expert user) in SPEC. Please, DO NOT DO IT as dtox is a macro motor dealing with two real motors (detm and detf) using encoders. If you reset the distance, you will just hide the problem without solving it but you will probably create new ones...!

Please, try to go deeper by checking if the wago controlling the two detector motor encoders (wcid232e) is in a good shape: you can check the error messages in spec(exp), ping it, use a webrowser (http://wcid232e) to see if you can communicate with it, etc ...  You can check as well in the spec(exp) window where, during the data collection, you could get informations about an error concerning wcid232e.

 

 

 

Experimental table positions lost after a "centrebeam":

 

You tried to realign the experimental table with the centrebeam button but you something went wrong (Adeline, it is for you!). You can try to move the table to latest known positions (macro motors) which are:

     thgt ~ -28.87 (table height)
     ttr ~ -1.28 (table translation)