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User name Yi Qiang
Log entry time 11:59:35 on May 09, 2009
Entry number 272098
This entry is a followup to: 272079
keyword=MCC Raster Screw Up
At around 11:59, after we asked MCC to increase the beam current to 5.5
uA and change the raster size to 4x4 so that we can continue the
productions, I first observed the black block on the middle room
oscilloscope showing the raster current very stretched vertically
dramatically!
Next thing Alex noticed was that the laser absorption spectrum decreased
to only about 1/3 of where it was.
Then the Neutron arm HV tripped and the target system gave an alarm
saying "the target temperature is too high!"
All of these indicate that due to incorrect large raster size the beam is
hitting the cell's wall. So we immediately requested MCC to shut down the
beam and investigate what caused this. Here is the
MCC
Elog entry
Fortunately, the cell is still there and all RTDs are still working properly.
After we checked raster size at empty target position and made sure
everything is back to normal, we continue the production from run 2039/20949.
A copy of this log entry has been emailed to: jpchen