Trips are frequent at 5
A, caused by scanners #3 and #4 and triggered by the
Compton ion chamber or BLM, even with chicane OFF. They are invasive for the
other halls. If a trip occurs, write in the e-logbook which scanner, forward/backward
(for this, you have to monitor the beam current during the scan), beam current,
arc tuning mode, which diagnostic tripped (ask MCC), get a strip chart of
this diagnostic (MCC). Contact the beamline coordinator ( Arun Saha) or the
hall leader (Kees de Jager) to allow MCC to mask the diagnostic. But in any case start
with unmasked diagnostics to have all safety systems responding. If masking
is impossible or not sufficient, reduce the beam current down to 1A but the
quality of the energy measurement will then be affected by the poor signal/noise
ratio.
If the trip occurred from scanner #3 or #4 during the preliminary test in achromatic mode, leave this step and ask for dispersive mode. In this mode, due to the dispersion of the beam, the luminosity will be reduced and hopefully the trip will not occur. Nevertheless, the test in achromatic mode is useful to check the system (including the trip protection!) and to anticipate a gain change for scanners #1 and #2.