Below is a brief summary of events this weekend.
Friday:
After a long day of beam tuning and BCM calibration in Hall A, we started taking data at about 8:30 pm. The trigger in the octants with quartz tubes (3,4,5,and 7) from multiplcity 3 to multiplicity 2. Under these conditions, the electron rate almost doubles, while the (fractional) contribution from randoms remains the same.
Saturday:
In the morning, Tanja and I made some polarization measurements with the Moller - we got about 86%. This was a relief since the Mott measurement right after the photocathode re-activation resulted in about 79%. I should note that the Hall B Moeller measurement also implied little or no change.
After the Moller running, Jay Benesch set up the hall C line for the "Moller quads off" tune in an attempt to mitigate the position stability issues we were seeing. This took a bit longer than planned, but we were taking data again by 2pm or so.
Riad tells me that the parity beam quality is fine with this tune and the position stability is much improved. However, Mat made a plot suggesting there is some increase in the Cerenkov singles rates. We'll need to keep and eye on this.
A power glitch at around 10:30 pm meant we basically were down for about 12 hours. When I arrived at 10:30 am Sunday, beam had just returned.
Sunday:
Once beam returned, we have just been taking production data. A plan from Herbert to test the current/rate dependence of the quartz tubes with the present trigger configuration has been deferred until more tubes are installed.
Plans:
Tomorrow we will install quartz tubes in 2 more octants: Octant 1 and either 6 or 8 (whichever works best at the time). We will open the hall first thing in the morning.