Operators: ajmasch seely manouch
doug: please advise...
at the beginning of this shift, ccr noted that the ring's ion clearers were not working. apparently, something had been unplugged a few days ago when ring work was being done. once fixed, the bqm rates at 60mA with the slits in were:
T = 360
L = 45
R = 30
B = 30
around 00:00 we finally got workable beam. we started taking empty target data. the chambers' signal to noise ratio was horrible. all six superlayers in the left sector had a 1:1 ratio. in the right sector, one superlayer in the middle chamber and one superlayer in the outer chamber had s2n ratios of about 2:1; the rest in the right sector all had 1:1 ratios. nsed, however, showed very few hits in the superlayers; definitely no noise trees.
we decided that the chambers might be charging up. the charging, though, could come from two different places: 1) the beam tuning or 2) bremsstralungh off of the new collimator.
to test if the charging came from scattering during the tuning process, we turned off high voltage to the chambers for an hour. that didn't help.
we then thought that maybe filling to 110mA might have been too high. so we tried filling to 70mA, but that, too, had no effect.
playing with the thresholds is next.
also, box L21 is tripping fairly often. we lowered it to 3700V, but i don't think that really helped. it trips about once per minute. we might just have to zero it.
aaron
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