GlueX Start Counter Meeting, November 17, 2011

GlueX Start Counter Meeting
Thursday, November 17, 2011 10 am EST
JLab: CEBAF Center, Room F326/7

Agenda

1. Announcements
2. Review minutes from previous meeting
3. Prototype Report
4. SiPM configuration
5. Contract Status
6. Simulation Status [1]

Communication Information

Video Conferencing

• ESNet: 8542553
• EVO:
  • Meeting URL: http://evo.caltech.edu/evoNext/koala.jnlp?meeting=292I2iMeMB9M9nDD9aD9
  • Phone Bridge ID: 10 1295

Slides

Talks can be deposited in the directory /group/halld/www/halldweb1/html/talks/2011-4Q on the JLab CUE. This directory is accessible from the web at https://halldweb1.jlab.org/talks/2011-4Q/ . You have to be a member of the "halld" Unix group to put files in this directory.

Minutes

Present:

• FIU: Lei Guo, Puneet Khetarpal
• JLab: Eugene Chudakov, Chuck Hutton, Mark Ito (chair), Tim Whitlatch

Prototype Report

Lei reports that they got the scintillators back from Plastic Craft after re-polishing. Three of them came back badly crazed. One was OK. He says they made two mistakes:

1. They ignored the recommendation to only use isopropyl alcohol to clean the surfaces. Instead they used a solution of isopropyl alcohol and naphtha. The naphtha is petroleum based and attacked the scintillator surface.
2. They processed the counters in the following order: bend, machine, then polish. Preferred is: machine, polish, then bend.

Plastic Craft has agreed to replace the scintillator and will try again with the new pieces. They will place an order with Eljen.

FIU will test the undamaged piece. Its surface quality seems to have improved after re-polishing.

SiPM configuration

Puneet reported that Werner has given it some thought and is considering a 1x4 or 1x5 array of 3 mm×3 mm devices. He is thinking of using these in a 30-paddle arrangement.

We need to find out what is available from Hamamatsu. It is looking like the geometry will be driven by how we arrange the SiPM's, with a scintillator/light-guide geometry constrained by that arrangement. It would be preferable to have flat light guides with no bend.

Simulation Status

overlap between rohacell

need to make target geometry consistent

need a tagged release

action item, update drawings

are flat sides polished? usually come smooth from manufacturer

one concern: puneet, straight portion,

this simulation 24 paddles

working on rate and radiation dose using geant4

Action Items

1. Test re-polished counter.
2. Research different SiPM arrangements from Hamamatsu.