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

[Fernando J Barbosa]

Hi Mark,

Maybe I missed something but the spacers were always part of the design. 
The question, as I understood at the meeting, was whether the spacers 
provided enough precision and uniformity during attachment of the ST1s.

Best regards,
Fernando


On 4/18/2014 11:42 AM, Mark Ito wrote:
> 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
>

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