Minutes 060905
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Attendees: Matt, Eric (Indiana), Elton, David, Elliott, Dan Carman, Blake, Rafael, Simon, Alex (JLab), Franz (CU), George, Garth, Kathryn, Zisis (Regina)
- Business Arising
- Action Items: See updated list below.
- Hall-B
- Status Quo: The BPM stand is 1/2 done. The crash-button post is pending; Eric can do it when he arrives if not done before.
- Electronics and Cabling: The CLAS cabling to the forward carriage and the Fast MOR are done. A few connections are left between the forward carriage and PIE tower that should be done today. The BPM cables have arrived; Fernando and David will pursue this. Elliott is pursuing direct signal cabling from the Hall to the counting house, for diagnostics on a scope. One of our scopes has TCP/IP connection and this can serve the said function as well.
- DAQ/online: Everything is functioning ok. The networking equipment arrived today and this work is still pending. Readout and processing of the tagger crates is a priority for this week.
- PMTs/Cosmics: Almost all PMTs look ok with the exception of 16N. The issue of spare bases was discussed and Regina/IU will order a couple of new VD124K bases for the XP2020 tubes. These require some minor rewiring which will be done at JLab. Concerns were raised about the considerably different amount of light deposited in the readout cells between cosmics and the beam. JLab has no attenuators, therefore attention has to be paid in the gain-setting stage. Fortunately, our ADCs are 12-bit. Cosmics data are being collected and analyzed, and preliminary plots have been shown by David and Alex.
- Run Plan: Zisis continues to update the Run Plan. The key issues discusssed today were:
- A proposal from Athens to use a high-field-resistant Hamamatsu R3809U PMT in the place of one of the Burle: Christine and Zisis decided that this was not worth the effort and the comparison can be done at Regina with cosmics.
- A proposal from Athens to use a pre-radiator in front of the BCAL was discussed. Christine's thought was to study and compare the depth profile of the generated e+e- vs. the photons. The material in the beam (including BPM and veto) account for less than 2% of photons converting to e+e- and the use of a pre-radiators of known thicnesses will contribute to this study further. It was agree that 0.5-3mm lead pre-radiator sheets should be placed in front of the BCAL. Regina will bring these, in 0.5mm sheets.
- A proposal from David to take measurements at different beam currents seemed to converge at a current range from 0.2-5nA. The idea is to study any possible PMTs sag due to current, effects on resolution and multiple hits, and as a general 'sanity check'.
- Monte Carlo:
- Rafael will simulate the effect of 0.5-3mm lead pre-radiator in front of the BCAL.
- Any other business
- If everything is 'routine' for the accelerator to return to operations on September 22, we can expect beam as early as 8am, but this is uncertain. We will plan to man shifts starting that day, which can be cancelled if there is no beam. The relative priority of the three Halls will be looked into and we will keep an eye on the 'Whte Board' in MCC.
- Franz will guide us through the startup procedure in Hall-B. Monday, September 25 has been set as a priority day for Hall-B and Franz will be present.
Action Items
- BPM, Veto: Slow control cables and stand construction pending.
- Light Leak: Light leak test pending in alcove.
- Tagger, Trigger, Cables: The fast core cable is pending.
- Data storage/Silo Request: David and Zisis will deal with this offline.
- Online Macros/MC Data steam/MC Validation & Binning: David and Zisis will work on these offline.
- Safety, COO: TOSP and ESAD are awaiting signatures. Elton has checked in the COO to the repository.
- Run Plan: Produce table with positions, angles, beam current, pre-radiator runs.
