Difference between revisions of "GlueX Start Counter Meeting, March 6, 2012"

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(Prototype Status)
(Mechanical Design)
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==Mechanical Design==
 
==Mechanical Design==
  
 +
Chuck walked us through the 3-D drawing of the current mechanical concept. A lot of discussion was generated.
  
accuracy of placement of sipm's with respect to scint. in transverse and longitudinal dimentions
+
* We discussed how to maintain the required accuracy of placement of the SiPM read-out boards with respect to the scintillator bars in both the in transverse and longitudinal dimensions.
 +
** Tim suggested that set screws to set longitudinal gap between scintillator and SiPM.
 +
** Werner pointed out that the critical dimension is in radial dimension since any mis-match loses light. He estimates we should control that dimension to about 200 microns.
 +
** Chuck pointed out that if we have more that three sections on the SiPM read-out boards, it would allow finer grained adjustment of position.
 +
** If there adjusts for position, we need to design in a way to tell that we are in good alignment.
 +
* To optically isolate the counters reflective material will be inserted between them. They will likely not be light-tight on a counter-by-counter basis.
 +
* Broadly, the construction concept we agreed on was to start with a precision machined rohacell inner shell, place counters around that shell, and apply the outer shell to that assembly. Then the complete assembly will be attached to the target support structure (aluminum or stainless).
 +
* We need to look at the Hall B support scheme for reference.
 +
* Tim pointed out that we would like to avoid using the target scattering chamber as a support structure for the nose section since any pressure on it could cause vacuum leaks.
 +
* Werner suggested that the whole start counter assembly could be held with springs against the target support structure.
  
set screws to set long. gap
 
 
werner: critical dimention in radial position
 
 
light tight requrement
 
reflective material separating counters
 
 
start with precision machined inner rohacell shell
 
add scint
 
add outer shell
 
 
look at support structure in hall b
 
support of target vacuum chamber, possibility of causing leaks
 
 
spriing loading, pull the structure back againsts target structure
 
 
200 microns on radial dimentions
 
 
more sectors allows more adjustiblity
 
 
need allignemnt criteria
 
need allignemnt criteria
  
Line 69: Line 60:
  
 
sasha has samples, maybe we can look at those
 
sasha has samples, maybe we can look at those
 +
 +
==New Action Items==
 +
 +
# Research Hall B start counter mounting scheme.
  
 
==Contract Status==
 
==Contract Status==
  
 
statement of work
 
statement of work

Revision as of 16:03, 6 March 2012

GlueX Start Counter Meeting
Tuesday, March 6, 2012
10 am EST
JLab: ARC, Room 428

Agenda

  1. Announcements
  2. Review minutes from previous meeting
  3. Prototype Report
  4. Contract Status
  5. Simulation

Communication Information

Video Conferencing

Slides

Talks can be deposited in the directory /group/halld/www/halldweb1/html/talks/2012-1Q on the JLab CUE. This directory is accessible from the web at https://halldweb1.jlab.org/talks/2012-1Q/ .

Chair's Cell Phone

(757)504-0664

Minutes

Present:

  • FIU: Werner Boeglin, Lei Guo
  • JLab: Chuck Hutton, Mark Ito (chair), Tim Whitlatch

Prototype Status

The first sample counter from McNeal is due in on March 14.

Mechanical Design

Chuck walked us through the 3-D drawing of the current mechanical concept. A lot of discussion was generated.

  • We discussed how to maintain the required accuracy of placement of the SiPM read-out boards with respect to the scintillator bars in both the in transverse and longitudinal dimensions.
    • Tim suggested that set screws to set longitudinal gap between scintillator and SiPM.
    • Werner pointed out that the critical dimension is in radial dimension since any mis-match loses light. He estimates we should control that dimension to about 200 microns.
    • Chuck pointed out that if we have more that three sections on the SiPM read-out boards, it would allow finer grained adjustment of position.
    • If there adjusts for position, we need to design in a way to tell that we are in good alignment.
  • To optically isolate the counters reflective material will be inserted between them. They will likely not be light-tight on a counter-by-counter basis.
  • Broadly, the construction concept we agreed on was to start with a precision machined rohacell inner shell, place counters around that shell, and apply the outer shell to that assembly. Then the complete assembly will be attached to the target support structure (aluminum or stainless).
  • We need to look at the Hall B support scheme for reference.
  • Tim pointed out that we would like to avoid using the target scattering chamber as a support structure for the nose section since any pressure on it could cause vacuum leaks.
  • Werner suggested that the whole start counter assembly could be held with springs against the target support structure.

need allignemnt criteria

don't forget temperature stabilization talk to fernando about temperature

sasha has samples, maybe we can look at those

New Action Items

  1. Research Hall B start counter mounting scheme.

Contract Status

statement of work