Log entry time 14:10:28 on December 03, 2004

Entry number 92393

• what we would like to run with is a 1*1 mm raster. This is what we could run with last week.
• what we can run with right now is 1.37*1.37 mm raster Why can't we go to 1*1 ?

  there is an administrtive limit that computes the maximum current density on the dump and fix the limit for the raster size. this limit depends on the beam current but not on target. the software implementation that enforces the limit suppose a square shape for the raster patern. changing the raster patern from square to rectangle requiere a hardware change in plus of the software change and is not simple to implement. the suspicion right now is that the beam current used by the software was not correctly entered.

  Why do we care and how much do wee care ?

  there is some suspicion that if the ratser size in x is too large the beam actually misses the target (in part)

  but we did not see any difference for the rates of electrons per uC in the sos between a raster size of 1.28 to 1.37 so we will be taking 1.37 by 1.37 mm for now