[Halld-pid] Start Counter Meeting Minutes, April 17, 2014

[Mark Ito]

Folks,

Please find the minutes below and at

https://halldweb1.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_April_17,_2014#Minutes

   -- Mark
___________________________________________________________________

GlueX Start Counter Meeting, April 17, 2014
Minutes

    Present:
      * FIU: Werner Boeglin, Eric Pooser
      * JLab: Fernando Barbosa, Eugene Chudakov, Mark Ito (chair)

Electronics

    Fernando gave us a report.

    All fabrication of ST-1, ST-2, and ST-3 boards is done. The signal
    split for ADC and TDC is now done on ST-3, not on ST-2 as before. The
    ST-3 testing is complete. The pre-testing (checking SiPM connections,
    etc.) of the ST-1s is done and the 10 ST-2s are being tested now. That
    should be done by tomorrow. After that the 30 channels on the ST-1s
    will be tested with a laser in the dark box. Also a test will be done
    to measure the electronic component of time resolution using the laser.
    It has a 100 ps rise-time and negligible jitter. This will be done with
    a complete chain from ST-1 to ST-2 to ST-3 to discriminator to TDC. A
    diffuser is used so that all four SiPMs can be illuminated. A set of a
    few amplitudes will be measured, and both ADC-bound and TDC-bound
    signals will be looked at. All tests should be done by the end of the
    month.

    On the mechanical side, there is a plan to do a test fit of the
    electronics on the aluminum support ring once that becomes available.

    When the items have been shipped to FIU, Nick Sandoval will go down and
    help to get the test set-up started. Fernando needs about one month
    notice to arrange travel.

    We had a discussion on the scheme for making sure that the ST-1 boards
    do not short against the aluminum support ring. [Added in press: this
    discussion assumed that there is no allowance for spacing washers in
    the design. This turned out not to be the case; a 40 mil washer is
    called out in the drawings. This rendered the discussion moot.]

    The group reminded Mark that we will not ship ADCs, TDCs, or
    discriminators to FIU for testing the detector there. FIU will use
    their existing read-out electronics. We will send an MPOD and all
    cables that connect the ST-2s to the ST-3. We discussed how many signal
    cables need to be shipped (those running from the ST-3). We decided to
    defer a decision on that.

    We decided that we should do a test mechanical assembly at JLab before
    shipping the support structure to FIU, including as much as is
    practical: support ring to target support, ST-3 on installation cart,
    cables from ST-2 to ST-3, etc. The exact plan needs to be worked out.

Schedule

    Werner laid out a very rough schedule given what we know now.
     1. scintillators arrive at FIU: mid-May
     2. scintillator testing and detector assembly done: end of June
     3. Nick visit: early July
     4. testing done: end of July
     5. ship to JLab: mid-August

Assembly Jig

    Eric presented the final design for the assembly jig. See his slides
    ([18]PDF, [19]Powerpoint) for details. Eric plans to call Chuck Hutton
    and discuss the design as well.

Progress at McNeal

    [Added in press: Eric talked to Robert McNeal just after the meeting
    and sent in this report.]

    All 50 paddles have been inspected and have passed the initial QA
    check. Machining of the paddles has not yet commenced. They are waiting
    for the machines to finish other jobs. However, production should begin
    within a week.

    Robert quoted that the paddles will be shipped out to FIU, no later
    than 05/02/2014 which is right at the 4 week lead time we were quoted.

    Eric provided Robert with the most up to date mechanical drawing of the
    paddles. There were no substantial differences between the two drawings
    and this update will have no negative consequences.

    Robert mentioned that they do quantify the final dimensions of the
    paddles after they are machined. This is done both optically and by
    machine. Standard operating procedure dictates that they will only
    measure approximately 8 of the 50 paddles. He is willing to provide us
    with this data. It is possible for them to inspect all 50 paddles and
    provide us with their associated measurements for a minor inspection
    fee initially estimated at $200.00. Further discussions will be made
    regarding whether we should purchase this inspection data.

References

   18. https://halldweb1.jlab.org/talks/2014-2Q/Finalized_Assembly_Jig.pdf
   19. https://halldweb1.jlab.org/talks/2014-2Q/Finalized_Assembly_Jig.pptx

-- 
Mark M. Ito, Jefferson Lab, marki at jlab.org, (757)269-5295