[Halld-pid] Minutes, GlueX Start Counter Meeting, March 22, 2012

[Mark M. Ito]

In the minutes, the link to Chuck's drawings of the start counter was 
missing. It is now there on the wiki. Or click on this: 
https://halldweb1.jlab.org/talks/2012-1Q/sc_3_22_12.pptx

On 03/22/2012 04:06 PM, Mark M. Ito wrote:
> Folks,
>
> Find the minutes below and at
> https://halldweb1.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_March_22,_2012#Minutes
>
>     -- Mark
>     _____
>
> GlueX Start Counter Meeting, March 22, 2012
>
> Minutes
>
>      Present:
>        * FIU: Werner Boeglin, Puneet Khetarpal, Eric Pooser
>        * JLab: Fernando Barbosa, Chuck Hutton, Mark Ito (chair), Beni
>          Zihlmann
>
> Prototype Report
>
>      We are still waiting for a prototype counter from McNeal.
>
> Readout Design
>
>      Since the last meeting, we had a meeting with Fernando to answer some
>      basic mechanical questions. At that meeting we decided on a
>      segmentation of 10, to aid alignment and to simplify fabrication of the
>      circuit board. Since then Chuck has done some work on the design and we
>      reviewed [? his slides] showing the latest version. He showed a new
>      scheme for attaching the start counter to the target vacuum chamber and
>      a circuit board concept showing the location of the individual SiPM SMD
>      components.
>
> Cooling
>
>      We had a short discussion on cooling. Fernando reported that in the
>      case of the BCAL readout it was recently discovered that non-uniformity
>      in the contact pressure between the cooling elements and the SiPM
>      arrays was causing temperature variation channel-to-channel with
>      attendant gain variation. For the start counter we plan to cool with
>      air flow so the details of maintaining a stable temperature are
>      different. Fernando suggested that we could use some sort of
>      heat-sink/heat-spreader/radiator to make sure there are no hot spots
>      among the read-out elements.
>
> Discussion of Design
>
>        * Chuck asked Fernando for some details on the non-SiPM side of the
>          boards, e. g. a rough profile of components, connectors, cabling,
>          etc.
>        * Werner suggested an alternate scheme for mounting where the entire
>          start counter array, including electronics, is assembled on a
>          separate rigid mounting collar independent of the target. The
>          current design has the counters mounted on the vacuum chamber first
>          and then the SiPM's aligned and fastened to the vacuum chamber as
>          well. In the alternate scheme there would be simple way to bolt the
>          mounting collar rigidly to the vacuum chamber. It would have the
>          advantage of providing a simple way to detach the start counter
>          from the target when/if that is required. The scheme would require
>          modification of the current design of the vacuum chamber, but it
>          was thought that this could be accommodated.
>        * We realized that now we are at the stage where the many details of
>          the mechanical design that need to be worked out, especially
>          related to supporting and light-tighting the scintillators and SiPM
>          read-out. We will try to arrange a meeting with Youri Sharabian to
>          review how some of these issues were solved for the Hall B start
>          counter.
>
> New Action Items
>
>       1. Get some details of circuit board design to Chuck. ->  Fernando
>       2. Arrange a meeting with Youri to discuss design details. ->  Mark
>
>      Retrieved from
>
> "https://halldweb1.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_March_22,_2012"
>
>

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