Operators: franklin shino tancredi
The trigger problem was solved after being traced to a poorly seated ECL
cable for the left neutron wall. The wire chamber spectra were much more
recognizable after this change. Signal--to-noise was about 1:1 and some plots
were made of the online spectra. We see almost no reconstructed events
in the z distribution.
After the trigger correction, the beam tune was improved in a few ways.
The most important of these was a change in the position of the top slit.
It had been suggested that the UP Beam Quality Monitor was broken, since
it was so much higher than the other 3 detectors. This may be correct, but
it does respond in a reasonable manner to beam conditions. Dave Bethka
was able to run the top slit position in by about 7 mm from its initial position
with no reduction in lifetime and significant improvement in the BQM's
(see e-log for new positions and rates) . There was also some reduction
in the trigger rate, which appears to be mostly TOF-neutron coincidences.
It was also verified that the ion clearers are working correctly. The beam lifetime
is still only 20 minutes (at 70 mA). Hopefully it will improve as the weekend
progresses, but we have concluded that it is good enough to allow us to
proceed with the run plan. We are taking empty target data and will continue to accumulate statistics for the next shift.
This archive was generated by hypermail 2.1.2 : Mon Feb 24 2014 - 14:07:30 EST