[Halld] Run Coordinator summary

[Alexander Ostrovidov]

Dear Collaborators,

I was Hall D Run Coordinator for a week from Jan 24 till Jan 31.
This was a productive week devoted mostly to collecting physics data.
We were scheduled to receive 168 hours of beam (i.e., 24x7), and we had
beam available for 106 hours. Out of them, we have used 90 hours (or 85%
of available beam) for actual data taking. During this week, we collected
close to 12.8 billion events bringing the total to about 26 billion
events so far for the Spring'18 run.

For the most part, the beam from the accelerator was acceptable. It has
developed frequent trips late on Sunday necessitating a maintenance day
for RF recovery on Monday (and, correspondingly, canceling the planned
Beam Studies day on Tuesday). There were a couple of relatively long 
(2-3 hours) unplanned downtimes. On Thursday, beam was off for 8 hours
to bring Hall A up. It went off for 2 hours for Hall B pass change on
Friday, and for 4 hours for Hall C pass change on Tuesday. Apart from 
these downtimes, the frequency of beam trips was kind of average. While 
beam position was stable, its convergence on the collimator was varying 
from good to marginal to acceptable without any obvious reason.

On Tuesday, CEBAF achieved a major milestone when CW was sent to all
4 halls at once at the highest energies (i.e., at 5 and 5.5 passes).
The only thing left for CEBAF to reach the design goals is to double
the maximum current delivered to Hall C.

Below is a brief summary of what was going on day by day.

Wed Jan 24 and Thu Jan 25:
We were taking production data almost all the time.

Friday Jan 26:
In addition to production, 2 hours of 300nA AMO high-luminosity run to 
study L1 trigger and DAQ response. 65kHz rate with 96% live-time was 
achieved. Also, drift chambers performed well under these conditions.
Later in the day, Hall went into Controlled access for 4 hours. During
this access, TPOL persistent noise problem was  fixed. TPOL
exhibits now the same clean signals it had a year ago. Baselines
of TPOL fADC were re-calibrated. Also, a dead TAGM channel was fixed.

Saturday Jan 27 and Sunday Jan 28:
These were quiet production data taking days until the machine developed
frequent trips toward the end of the weekend.

Monday Jan 29:
Accelerator maintenance day. A few tasks were performed during this time.
A few dead TAGM channels were brought back to live and HV scan was done. 
A dozen of FCAL HV bases were replaced. TRD detector was rearranged. 
Suspicious TPOL channel was looked at. After the beam came back in the
evening, we returned to production runs.

Tuesday Jan 30:
Once again, mostly production data taking.

Wednesday Jan 31:
Started empty target runs at 6am, including a raw-mode run.
For a short time, studied chamber currents without a radiator and 
with/without a collimator. At 9am, started TAC run which is still
ongoing.

As of now, our hardware seems to be in the top shape not counting
a dead channel here or there. There are a few issues requiring
further attention: improving beam convergence, measuring polarization,
understanding variations of the trigger rates for apparently the
same beam flux. But nothing prevents us from continuing to collect
good physics data.

Sasha