[Halld] Update on commissioning

[Alexandre Deur]

Dear collaborators,

We had good beam during the day. The first phase of the fast feedback commissioning was done today by Trent Allison. He will continue his work tomorrow and Friday. At the same time, Sergey Furletov was able to continue commissioning the DAQ and Alex Barnes finished his microscope bias studies. Then, the goniometer commissioning was finalized. This concludes the most important task we had set ourselves for this short 6 GeV commissioning. Ken, Hovanes and Paul did a terrific job, much quicker than we anticipated it would take. Alex Somov has completed yesterday evening and during the night his pair spectrometer trigger optimization. He is presently continuing the optimization of the production trigger. 

We will do production running overnight, with some empty target run tomorrow morning. This will be followed  at 9am by the second part of the fast feedback commissioning, although this task may be delayed to synchronize a Hall D access prerequisite to the fast feedback work with an invasive Hall A task.

This commissioning is already bringing many encouraging results:

The coherent peak was seen both on the hodoscope and the pair spectrometer detectors, see Ken Livingstone's entry https://logbooks.jlab.org/entry/3335562 and Alex Somov's entry https://logbooks.jlab.org/entry/3336327

>From the straight track runs, Simon has reconstructed the event vertex distribution and we can nicely see the 30 cm LH2 target, the kapton foil at the nose and the solid plastic target some dozen cm downstream, see https://logbooks.jlab.org/entry/3335407
Also, Simon posted graphs showing multi-tracks and multi-detectors events, see response https://logbooks.jlab.org/entry/3336214

Nice pi0 peaks are seen both from BCal, see Will's entry https://logbooks.jlab.org/entry/3336284 , and from FCal, see Justin's entry https://logbooks.jlab.org/entry/3336229 
These results, also underline the great progresses made on the DAQ and trigger compared to the 2014 Fall run: In 3.5h, BCal gathered 20% of the total amount of pi0 events we got during the Fall run.

Best regards,
 
Alexandre Deur, Hall D Run Coordinator.
 
RC cell: 757-383-5542
Office Phone: 757-269-7526