South Hall was open today. ABS nozzle was warmed up. Superconducting
solenoids were filled.
Aaron replaced a sense wire in one of the cells associated with WCL14 HV
trips. Hopefully this is what was causing the trips, although it could be
one of the other 2 sense wires in that cell, or possibly a guard wire. The
box holds more voltage (3900V) without beam than before (by 100V), but
still not the 4000V standard.
Michael investigated the ringing on some of the LADS phototube signals,
which causes discontinuity in the time walk spectrum (ADC vs. TDC). The
ringing is present at the base, and can be tuned out with an RC
circuit. The need for such a correction, and which tubes to apply it to,
will be considered this week. Corrections could be applied next Tuesday
during the SH open day.
Fiber optics are now connected to both the L and R BATS. Be careful when
moving the BATS and/or the detector subframe; there is not a lot of slack
in the fibers.
Townsend and Dan Cheever are in the process of measuring the BLAST field,
looking for correlations with water temperature (seen by the beam). They
will also measure the field at the same place in the left and right sector,
to rule out any field difference causing the tensor polarization
mysteries. After this, Aaron will remove the wire chamber covers, close
the detector subframe, and we'll be ready to run for the night.
The nozzle is cooling down. ABS should be available around 5pm. Beam
should also be available about then.
The plan for tonight is to run deuterium as we have been running. I
changed the singles prescale factor from 30 to 10, so we should get more
singles (PHYS6, or trig==7). This shouldn't affect the livetime much.
Tomorrow morning we will likely reverse the transverse holding field and
run that way for 24 hours. It will take 2-4 hours to retune the beam (and
the ABS transitions at the same time). This may provide some clues in the
L/R tensor asymmetry discussion.
Karen
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