Minutes 060609

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Attendees: Alex, Chris, Eric (Indiana), David L., Elliott, Elton (JLab), Curtis (CMU), George, Rafael, Zisis (Regina)

  1. Business Arising
    • Hall-D Meeting Participation: Doug Tillis attends the Wednesday morning meetings. In return, Elliott will attend the Friday morning Engineering Meetings when necessary.
    • Fast/Air core cable: We will not need this. We will be using existing CLAS cables as the Alcove is about 40 ft away from the CLAS 'nervous system' located on the forward carriage.
    • Data Storage: See action item list below.
  2. Detector Setup/Mechanics
    • Status Quo:
      • Indiana: Work is progressing well. Minor hickup on the dimensions of the light guides (LGs): they were 4cm whereas IU thought they'd be 1.5 inches. Eric will check all tolerances and make sure all is ok. Pictures of the cart with electronics and computer have been posted to the Portal (image gallery). The computer runs RHE4 and can be accessed remotely via ssh and DHCP. There should be two network switches in the Alcove area that can accommodate connection. Alex and Chris reported on the reflection tests for the LGs and showed a picture of the setup (also now on the image gallery). A LED and fiber system are used to shine light into the clear face of the LG with the PMT sitting on top. There are plans to scan the fiber across the surface. Initial tests show that mylar+grease is 20% better than bare. Next a frame will be made to clamp the mylar in place. White paint degrades the output. Reflective paint from BICRON causes loss (10%) to diffusion. Also, glueing tests will be done.
      • Regina: Zisis is looking into mu-metal foil and Si cookies (see action item list). For the later, Sylgard 527 (from Dow Corning) looks like a candidate. However, this comes as a two-part (1:1) compound and may require a vacuum jar to remove the air bubbles during mixing. Bicron (BC634A) and Eljen have ready made sheets. The thickness was discussed. BICRON offers 3 and 6mm thick.
      • CMU: Four production light guides were shipped to IU for tests. All pieces are 4x4cm2. Curtis will arrange for JLab to cover shipping costs to IU and Regina.
      • JLab: Things are progressing on schedule with a completion date on August 20th. We need to communicate our needs re craning and alignment (no of hours) to the engineers. We will not be needing a staging area, as the plan is to move the equipment straight into the Alcove area as soon as it arrives at JLab. We will request the 3He bag from CLAS to the Alcove; it can be bent down just before the BCAL module.
    • Beam profile monitor in Hall-B: David L. sent an email to David Cashy about this but no reply so far. Stephan said that thsi should not be a problem and that we should not use the CLAS one but rather the Primex one. It can plug into EPICS.
  3. DAQ/Electronics
    • Status Quo: The electronics have been collected at the DAQ lab. A cable issue (wrong polarity) has been resolved.
    • Tagger and Trigger: Pending (see action list below). Information from Eugene is posted below. The rates and collimator impact were discussed. Regina will simulate the latter. It was decided that 100 kHz rate for t-counters is where we should run.
  4. Online software
    • Coda/Coda-lite: Coda will be our default, running on RHE4. (Coda-lite will be a backup but it still has no control gui).
    • Online macros/checks: David L. proposed the use of ROOT and this was agreed upon. David will investigate 'stealing' events from the data stream and running them through DANA.
    • e-log: After some increased JLab security work, we hope that Greg Riccardi will install the e-log for the beam tests around June 16.
  5. Monte Carlo:
    • Status Quo: PAW ntuples are produced with (E, t) information for each of the 36 readout sectors. This will be switched to ROOT trees. The OpenShop browser-interface is operational in Regina and plain condor ntuples will be made available.
    • Output format/data stream/macro type: The MC and cosmics data will be digitized (evio format). David L. will write code to produce low-level check histograms (for inspection during the run) and ROOT trees for analysis. Zisis will provide requirements for ROOT trees.
  6. Offline analysis
    • Standalone: Rafael and Blake will be tackling this at Regina.
    • DANA: David L. is focused on charged particle tracking for PAC30 document for now and will work on DANA for BCAL later on.
  7. Any other business
    • PAC 30 Document: Alex will have a draft by Monday and several others are expected to contribute.
    • Slides for CLAS: Alex and Zisis will provide 2 slides on the Hall-B beam tests to Volker for presentation during the CLAS meeting.

Action Items

  1. Craning and alignment: Elliott, Zisis and Eric S. will work this out and communicate to David Cashy on this issue.
  2. CLAS cables: Elliott will investigate the cable issue from forward carriage to Alcove.
  3. Network switch: Elliott will check out the availability of the network switches in the Alcove area.
  4. BPM: David L. will contact Mark Ito and others to investigate availability and functionality of BMP.
  5. Collimator: Rafael will simulate collimator size effect on energy leakage from the module's sides.
  6. Electronics: Elliott and Zisis will run through the checklist.
  7. Tagger and Trigger: Paul Smith, Elliott, Franz Klein and Zisis will refine the trigger logic and tagger demands offline.
  8. Mu metal foil: Elton will send company addresses to Zisis.
  9. Si Cookies: Alex will send related paper to Zisis. Zisis will investigate the thickness issue.
  10. Data storage: David L. and Zisis will deal with this offline.
  11. E-log: Greg Riccardi continues work on the GlueX e-log.
  12. Online Macros/MC Data steam/MC Validation & Binning: David L. and Zisis will work on these offline.
  13. MC results: Zisis will make ntuples publically available.


Notes for item 2, tagger and trigger timing, etc (from EJW): 

1.  We should install He bags;  need to submit requirements doc to H-B for this and other beamline components
    incl. radiator thickness, collimator size, pair-spec and other magnet needs, etc.

2.  Tagger trigger timing (thanks to Eugene Pasyuk):
  20 ns      transit time in T-counter PMT
  50 ns      cable to CFD
  10-15 ns   internal CFD
  5 ns       cable to L-R coincidence module
  5 ns       internal coincidence module
  10 ns      cable to Master OR module
  20 ns      internal Master OR
  80 ns      cable to forward carriage
  50 ns      patch cables from forward carriage to BCAL test trigger rack
  -----
  250 ns     signal delay electron hits radiator until Master-OR arrives at our rack

Note that photon flight time to alcove is approx 100 ns (need to check with Mike Zarecky).  Also note 
that T-counter cables are trimmed to give equal time signal at L-R coincidence module.

If I recall,  Richard said RadPhi has both 250 ns cables and 80 ns cables running from the 
alcove to the RadPhi racks.
  
Still to be determined:  BCAL signal timing, time to create BCAL trigger, length of cable running from
forward carriage back to tagger, etc. 

3.  Tagger uses LeCroy 1877 multi-hit and CAEN pipelined TDC's; both run in common-stop mode.

4.  CAEN V792 ADC (BCAL readout) is slowest and sets front-end busy time.  May skip busy and just 
    use front-end-busy-timer in TS, as V792 has fixed digitization time of approx 7 microsec.
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