[Halld-pid] Start Counter Meeting Minutes, June 28, 2012

[Mark M. Ito]

Folks,

Find the minutes below and at 
https://halldweb1.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_June_28,_2012#Minutes 
.

   -- Mark
_____

GlueX Start Counter Meeting, June 28, 2012
Minutes

    Present:
      * FIU: Werner Boeglin
      * JLab: Eugene Chudakov, Chuck Hutton, Mark Ito (chair), Beni
        Zihlmann

Prototype Testing

    Eugene asked how Werner's [20]recent timing resolution measurements
    were done, with cosmics or a source. Werner used a Sr90 source with a
    trigger counter on the opposite side of the start counter paddle from
    the source. The end-point of the beta spectrum is 2.2 MeV, so the 3 mm
    thick start counter filters out the low energy electrons. Werner has
    done tests before on different counters using both cosmic rays and the
    Sr90 source and those have been consistent with each other.

    Werner is still planning to buy two or three counters from McNeal.

    Werner expressed some concern in using the relatively think VM2000
    material to isolate the counters from each other. He was concerned that
    the thickness might add mechanical pressure and degrade the
    reflectivity of the edge surfaces. He will try various materials in the
    three-counter prototype to see if other materials do better, for
    example double-sided aluminized mylar.

Read-Out Design

    The circuit boards for the SiPM read-out have come back and Nick
    Sandoval has assembled some using the 50 micron SiPM's we have on hand.
    The plan is to use 100 microns in the final detector; some of those are
    due in this week. Fernando Barbosa reported that we are still waiting
    for the mini-coax cable that routes connections to the break-out board.

Mechanical Design

    Mark talked to Youri Sharabian about the Hall B start counter:
      * the outer foam was for protection only
      * the inner foam was made of single piece of [21]Last-A-Foam from
        [22]General Plastics.

    See [23]Mark's email for details.

    Werner has been thinking about the jig for assembling the complete
    detector. He is thinking of using pneumatically driven pins to hold the
    counters in place before an outer wrapping is done. That way the
    pressure can be controlled more easily than with set screws. Tim will
    look into candidate parts for doing this.

Contract

    Mark will send the TOF Statement-of-Work to Werner as an example of
    what we need.

Simulation

    Puneet Khetarpal has been working on background studies; there are some
    consistency checks that need to be done. We should hear from him at the
    next meeting.

    Retrieved from
"https://halldweb1.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_June_28,_2012"

References

   20. 
https://halldweb1.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_May_31,_2012#Prototype_Tests
   21. http://www.generalplastics.com/products/rigid-foams/
   22. http://www.generalplastics.com/
   23. https://mailman.jlab.org/pipermail/halld-pid/2012-June/000351.html

-- 
Mark M. Ito
Jefferson Lab (www.jlab.org)
(757)269-5295