Difference between revisions of "GlueX Start Counter Meeting, July 28, 2011"

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* '''JLab''': Eugene Chudakov, Mark Ito (chair), Puneet Khetarpal, Sascha Somov, Simon Taylor, Tim Whitlatch, Beni Zihlmann
 
* '''JLab''': Eugene Chudakov, Mark Ito (chair), Puneet Khetarpal, Sascha Somov, Simon Taylor, Tim Whitlatch, Beni Zihlmann
  
 +
==Prototype Status==
  
−
box in operation
+
* The dark box is in operation.
−
using to test long solid light guide
+
* Current set-up uses the 140 cm solid light guide.
−
at end of 140, lose factor of 2 in time resolution
+
** Previous tests showed a loss of a factor of two in time resolution when using the light guide vs. placing the phototube at the scintillator. That counter was 6mm x 10 mm.
−
6mm thich by 10 mm wide
+
** Tests were done with and without reflective wrapping material.
−
10 mm wide scintillator
+
** Using optical grease helped; degradation was only a factor of 1.5.
−
tried using without wrapping
+
* Scintillator from Plastic Craft has been tested.
−
and with reflective material,
+
** By eye, the quality is not so great. There are scratches and some look milky.
−
used grease -> 1.5
+
** Tried test with the piece (of five) that looked the worse.
−
 
+
** With a FMPMT directly on the scintillator got 300-400 ps resolution in the flat section and most of the tapered section, but see 600 ps at the forward point.
−
got scintillator from plastic craft
+
** Judging from the previous tests, expect that with the light guide we will see a resolution range of 600 ps to 1 ns.
−
look at them recently
+
** Light output may be improved by improving surface quality of the counters.
−
quality not that great, scratches, milky
+
** Want to measure all 5 counters to see if response if uniform
−
scintillato that looks worse
+
** Vapor polishing looks like promising option.
−
at tend of scintillator, 300-400 ps
+
* Setting up to test fiber light guide
−
bend section, just about as good
+
** A new mounting scheme has been built.
−
go to small point , 600 ps
+
** These should have better light transmission.
−
fmpmt
+
−
connect to light guide, 600 ps- 1 ns expected
+
−
can be improved by scint surface quality
+
−
want to measure all 5 to see if response if uniform
+
−
vapor polishing look promising
+
−
 
+
−
today, tried fiber light guide, new mounting
+
−
will be connecting to try
+
−
now working only with photomultipliers
+
−
intrinsically better resolution
+
  
 
fmpmt, max field one tesla, orientation crucial, at 30 degrees, optimal
 
fmpmt, max field one tesla, orientation crucial, at 30 degrees, optimal

Revision as of 08:47, 29 July 2011

Location, Time

Thursday, July 28, 2011
3:30 pm EDT
JLab: CEBAF Center, Room F326/7

Agenda

  1. Announcements
  2. Review minutes from previous meeting: all
  3. Start Counter News
  4. MOU status

Communication Information

Telephone

To connect by telephone:

  1. dial:
  2. enter access code followed by the # sign: 3421244#

Video Conferencing

Slides

Talks can be deposited in the directory /group/halld/www/halldweb1/html/talks/2011-3Q on the JLab CUE. This directory is accessible from the web at https://halldweb1.jlab.org/talks/2011-3Q/ . You have to be a member of the "halld" Unix group to do this.

Minutes

Present:

  • FIU: Werner Boeglin, Lei Guo, Eric Pooser
  • JLab: Eugene Chudakov, Mark Ito (chair), Puneet Khetarpal, Sascha Somov, Simon Taylor, Tim Whitlatch, Beni Zihlmann

Prototype Status

  • The dark box is in operation.
  • Current set-up uses the 140 cm solid light guide.
    • Previous tests showed a loss of a factor of two in time resolution when using the light guide vs. placing the phototube at the scintillator. That counter was 6mm x 10 mm.
    • Tests were done with and without reflective wrapping material.
    • Using optical grease helped; degradation was only a factor of 1.5.
  • Scintillator from Plastic Craft has been tested.
    • By eye, the quality is not so great. There are scratches and some look milky.
    • Tried test with the piece (of five) that looked the worse.
    • With a FMPMT directly on the scintillator got 300-400 ps resolution in the flat section and most of the tapered section, but see 600 ps at the forward point.
    • Judging from the previous tests, expect that with the light guide we will see a resolution range of 600 ps to 1 ns.
    • Light output may be improved by improving surface quality of the counters.
    • Want to measure all 5 counters to see if response if uniform
    • Vapor polishing looks like promising option.
  • Setting up to test fiber light guide
    • A new mounting scheme has been built.
    • These should have better light transmission.

fmpmt, max field one tesla, orientation crucial, at 30 degrees, optimal

tim want drawing, straight 394 mm straight, bend readius 20 mm, 17 degrees

werner will send drawing to tim

werner thinks cylindrical, eugene raised lots of fiber if you come up with idea on bend section then werner will try might lose a lot of light

sipm fernando, managed to get sub ns resolution, bias voltage not stable, added capacitor close to sipm, bypass cap, rise time went to 5 ns, decay issues

sasha 180 ps for 3mm sipm 20-22 ns 16 ns

MOU going around for signatures

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