Run Coordinator report: Spring 2017 r4
Dear Collaborators,
below is my report as run coordinator from February 23 to March 1st.
Short Overall Summary:
Overall we had a productive week with reasonably stable beam (96.3h or 62% of scheduled hours). We collected a total of about 12 B events and reached an estimated total of 37 B out of the planned 60B. We also increased the average beam current from 100nA to 150nA and took data at an average rate of 50kHz which translated to a data transfer rate of 800- 900 MB/s. While overall the livetime was high (>95%) the DAQ had to be restarted repeatedly as we observed that the livetime would suddenly start to fluctuate and eventually drop to 0. In order to study the exact source of this problem the CODA group installed additional diagnostic tools which should help in solving these issues. We performed also a TAC measurement using the 3mm collimator with an inset that effectively reduced the collimator size to 1mm. We took a total of 3M triggers in this configuration at an average beam current of 9-13 nA. This TAC measurement was shorter than planned and more TAC measurements are needed.
Day by Day Summary:
Feb 23) The active collimator (AC) developed a problem, that turned out to be due to the loss of a low voltage power supply for the pre-amps. The consequence was that the signal of the AC was such that the beam lock steered the beam away from its optimal position resulting in a beam trip or unusable beam. This lead to a down time of about 12h. We Recorded about 1.4B triggers during the last 24h
Feb 24) We switched to 150nA and the DAQ rate was up to 50kHz. Sasha performed trigger studies and Lubomir was able to run tests for the TRD. In the evening we lost the beam for about 4 hours due to a vacuum trip in the accelerator followed by a water chiller warning in the Hall which was fixed after a controlled access and rebooting a controller. Otherwise it was a productive day. We collected a total of 1.6B triggers.
Feb 25) Overall we had stable beam which was interrupted when a weather font passed though (wind , thunder and hail). We continued fighting with the DAQ to keep running at 50kHz with good livetime. Several detector systems needed to be adjusted for higher beam current (FCAL, FDC, TOF, CDC TAGM) also part of the tagger hodoscope was turned of. We were able to recors 2.0B triggers. Carried out harp scans but did not ask for re-focusing the beam as the PS coincidence rate looked good and the beam positions were fine as well.
Feb 26) Similar to the previous day except without the weather interruption. Repeated DAQ and monitoring restarts were necessary. We collected 3.3 B triggers
Feb 27) It was observed that some tagger microscope channels showed low count rates after the adjustments for high rates. This will be addressed during the maintenance day. We continued data taking and carried out a TAC run in the evening using the 3mm collimators with a 1mm inset. The current was set to be about 10nA and the TAC rate around 70kHz. Using a 750micron Be converter the PS coincidence rate was 4 Hz. We carried out 2 runs and collected a total of 3M triggers. Afterward we switched back to data taking. The entire procedure, took 6 hours. We collected a total of 2.8B production triggers.
Feb 28) Beam was turned off at 7am for maintenance day and the Hall was placed in Controlled Access. Benni reduced the discriminator signal widths from 40ns to 20ns. Alex Barnes re-adjusted the microscope thresholds and gain to recover those channels that were 'lost' after the adjustment for high rate. A few FCAL bases needed to be replaced and a connector repaired. All work in the Hall was completed by 2pm when it was placed back into Beam Permit. The beam was returned at 20:30 and first Harp scans were carried out. After running the special focusing script (Todd's script) the focusing was worse and it was discovered that the beam was not at the correct location.
Mar 1) The overall adjustment of the beam took about 6 hours and a discussion of these procedures and their criteria is needed. After resetting all steering settings to their pre-optimization values basically no FCAL events were observed. Sergey observed a very high rate (MHz) in some of the FCAL crates but these rates were not observed in the scalers. Finally it was found that the red light was left on in the dark room of the FCAL. Regular data taking started again at 10:30
Werner Boeglin
