Difference between revisions of "GlueX Start Counter Meeting, December 20, 2010"

From GlueXWiki
Jump to: navigation, search
(Minutes)
(Minutes: complete draft)
Line 27: Line 27:
 
* '''JLab''': Mark Ito, Sascha Somov
 
* '''JLab''': Mark Ito, Sascha Somov
  
==Start Counter News==
+
==Wrapping material==
 
+
===Wrapping material===
+
  
 
Paul Eugenio has sent some ESR sheets sent to FIU. They have not been received yet.
 
Paul Eugenio has sent some ESR sheets sent to FIU. They have not been received yet.
  
===Counter Fabrication===
+
==Counter Fabrication==
  
 
Lei has had futher contact with the company that is fabricating light guides for the CLAS12 central TOF.
 
Lei has had futher contact with the company that is fabricating light guides for the CLAS12 central TOF.
Line 42: Line 40:
 
* Practice for the company with plexiglass seems the likely next step.
 
* Practice for the company with plexiglass seems the likely next step.
  
===Neutrons and SiPM damage rates===
+
==Neutrons and SiPM damage rates==
  
Sasha reviewed the damage estimates on [[???|his wiki page]].
+
Sasha reviewed the damage estimates on [[Comparison of radiation damage between FLUKA and Geant|his wiki page]].
  
• dose comparable to bcal SiPM region
+
* The damage rate is comparable to that of the downstream end of the BCAL.
• polyethylene shielding helps, studied for the tagger, factor of 7
+
* Polyethylene shielding helps. This was studied for the tagger and reduced the damage rate by about a factor of 7.
support structure could be made out of shielding material
+
** The support structure itself could be made out of shielding material.
 +
* The start counter is a timing application, not an energy measurement. That should increase its tolerance to dark current.
  
• W. wants to look with new SiPM. timing dominated by light output
+
==Further Tests==
• Richard simulated discriminator with damaged sipm, timing resolution OK with a factor of 50 increase in timing resolution, he expects 300 pe total
+
• W. can change  current with temperature.
+
• sc rate 12 kHz, vs 1 MHz for microscope
+
• ask Carl how hot does it have to be.
+
  
• focus on SiPM
+
* Werner wants to look at new scintillator bars with new SiPM. So far the timing resolution has been dominated by light output.
• same SiPM as BCAL
+
* Sascha reported that Richard Jones simulated discriminator response in the microscope with a SiPM with elevated dark rate. He found that the timing resolution was OK with a factor of 50 increase in dark rate. For the microscope he expects 300 pe's total.
• W has a 4x4 array
+
* Werner suggested that we can change dark current with temperature in order to test timing response.
• W has one, F10943, Hamamatsu
+
** We need to ask Carl Zorn how hot does it have to be.
ask Carl for another one
+
* Sascha quoted a start counter rate of 12 kHz, versus 1 MHz for the microscope.
• language
+
* Werner has a 4x4 array: Hamamatsu F10943.
• MRI possibility
+
** Sascha suggested we ask Carl for another one.
 +
* Werner is changing his set-up to do light output measurements to accommodate the SiPM as main detector.
 +
* The new scintillators he plans to use are:
 +
** 2 mm and 3 mm thick, 12 mm and 15 mm wide
 +
** The 15 mm wide counters could be used for a 30 element design.
 +
** Since he observed light output reduced by edges, a wider wider counter has less edge area fractionally.
 +
* The plan is to focus on the SiPM solution, using the same one as for the BCAL.
  
• changing set-up to do light output measurement to accomodate SiPM as main detector
+
==Other Items==
• new scintillators as well, 2 mm and 3 mm
+
• 12 and 15 mm wide: 30 element for 15 mm
+
• light output reduced by edges, wider has fewer edge area fractionally
+
  
light guides design
+
* Werner mentioned the possibility of funding the project through an MRI.
+
* The light guide design is non-trivial. Although there is a rough match in cross sectional area between the scintillator and SiPM, the aspect ratios are pretty different.
• tin viewer
+

Revision as of 10:23, 21 December 2010

Location, Time

Monday, December 20, 2010
1:30 pm EST
JLab: CEBAF Center, Room F228

Agenda

  1. Announcements
  2. Review minutes from previous meeting: all
  3. Start Counter News: Werner
  4. Neutron flux and Start Counter SiPM's: Sascha
  5. Photodetector decision process: all
  6. MOU plans: all

Communication

Conference Group, US: 800-377-8846, Canada: 888-276-7715, International: 302-709-8424
   participant code: 77438230
ESNet: 8542553
EVO: direct meeting link, phone bridge ID: 7 7569
Slides: talks can be deposited in the directory /group/halld/www/halldweb1/html/talks/2010-12 on the JLab CUE. This directory is accessible from the web at https://halldweb1.jlab.org/talks/2010-12/ .

Minutes

  • FIU: Werner Boeglin, Lei Guo
  • JLab: Mark Ito, Sascha Somov

Wrapping material

Paul Eugenio has sent some ESR sheets sent to FIU. They have not been received yet.

Counter Fabrication

Lei has had futher contact with the company that is fabricating light guides for the CLAS12 central TOF.

  • They can do bending for no extra charge.
  • They estimate a failure rate of 3 out of 8.
  • The cost should be a few hundred dollars per counter.
  • One possibility is to buy scintillator in sheets and have the company do the cutting, bending, and polishing.
  • Practice for the company with plexiglass seems the likely next step.

Neutrons and SiPM damage rates

Sasha reviewed the damage estimates on his wiki page.

  • The damage rate is comparable to that of the downstream end of the BCAL.
  • Polyethylene shielding helps. This was studied for the tagger and reduced the damage rate by about a factor of 7.
    • The support structure itself could be made out of shielding material.
  • The start counter is a timing application, not an energy measurement. That should increase its tolerance to dark current.

Further Tests

  • Werner wants to look at new scintillator bars with new SiPM. So far the timing resolution has been dominated by light output.
  • Sascha reported that Richard Jones simulated discriminator response in the microscope with a SiPM with elevated dark rate. He found that the timing resolution was OK with a factor of 50 increase in dark rate. For the microscope he expects 300 pe's total.
  • Werner suggested that we can change dark current with temperature in order to test timing response.
    • We need to ask Carl Zorn how hot does it have to be.
  • Sascha quoted a start counter rate of 12 kHz, versus 1 MHz for the microscope.
  • Werner has a 4x4 array: Hamamatsu F10943.
    • Sascha suggested we ask Carl for another one.
  • Werner is changing his set-up to do light output measurements to accommodate the SiPM as main detector.
  • The new scintillators he plans to use are:
    • 2 mm and 3 mm thick, 12 mm and 15 mm wide
    • The 15 mm wide counters could be used for a 30 element design.
    • Since he observed light output reduced by edges, a wider wider counter has less edge area fractionally.
  • The plan is to focus on the SiPM solution, using the same one as for the BCAL.

Other Items

  • Werner mentioned the possibility of funding the project through an MRI.
  • The light guide design is non-trivial. Although there is a rough match in cross sectional area between the scintillator and SiPM, the aspect ratios are pretty different.