Re: [ccp4bb]: Problems with low mosaicity crystals

[Richard Gillilan <reg8@cornell.edu>]

***  For details on how to be removed from this list visit the  ***
***          CCP4 home page http://www.ccp4.ac.uk         ***

Yong: which station did you use at CHESS and when?
Also, what detector did you use at APS?

I would love to know what other folks are seeing
for R factors in low resolution bins

If responding, please give as much info as you can ...

      detector type
      sync/or lab source
      mosaic spread
      resolution range for R factor
      exposure time
      phi angle increment for rotation

(To find this info, check your scala log file)

--- I will summarize to the list. ---

I also believe that vibration in the coldstream would
appear as increased mosaic spread. Angular oscillation of the
crystal (several Hz) would be time-averaged over the
exposure and have similar effect as classic random distribution
of microcrystal domains ... though maybe the distribution
would be biased by the xtal spending more time at the turning
points of the vibration period. Hard to say how much angle
variation, but you can see it a little. Mosaic spread in flash-cooled
crystals is, however, dominated by lattice-spacing variations
caused by the cooling process and NOT microdomains (IMHO).


Richard