GlueX TOF Meeting, December 12, 2011

From GlueXWiki
Jump to: navigation, search

Monday, December 12, 2011
9:30 am EST
JLab: CEBAF Center, Room F326


  1. Announcements
  2. Minutes from the last meeting
  3. Mechanical design: Tim, Chuck
  4. Prototype status: Paul, Sasha, Beni, Test Stand at FSU
    • Trip Report
    • Splitter or dynode for ADC?
    • Prototype studies [1]
  5. Contract Status: Mark
    • Construction Manual
    • Quality Assurance Plan/Acceptance Procedures
    • Construction Manager
    • Construction Schedule



  1. ESNet: 8542553
  2. EVO: EVO site


Talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2011-4Q on the JLab CUE. This directory is accessible from the web at .



  • FSU: Paul Eugenio, Sasha Ostrovidov
  • JLab: Eugene Chudakov, Chuck Hutton, Mark Ito (chair), Simon Taylor, Beni Zihlmann


  • Chuck received the of new light guide design. Looks good.
  • Paul is ready to try cutting the VM2000 for light guide wrapping. Chuck will send him a 2-D projection of the light guides to serve as a template.
  • Paul will look into getting large sheets or rolls of the VM2000 again.

Trip Report: Work at FSU

Beni reported on work he, Sasha, and Paul did during Beni's recent trip to FSU (November 28 through December 2). He led us through his wiki page summarizing the work. He described:

  • cosmic ray test stand at FSU
  • PMT gain measurements
  • revised PMT current estimates
  • time difference resolution measurements

Most encouraging, he gets a Δt/2 resolution of 80 ps near the center of the TOF prototype.

We agreed that the trip was very useful and will help with communication in the future.

Prototype Tests

Sasha showed progress in the last week with the prototype. See his web page for details. He showed:

  • improvement in trigger counter time difference measurements after Paul changed the phototubes
  • improved separation between pedestal and signal in the TOF prototype paddle with a longer ADC gate

PMT Choice

We discussed the various option for the PMT purchase. Beni agreed to summarize the arguments and proposals and send them out to the list.

[Beni sent out his summary soon after the meeting.]

Attaching the PMT's

We discussed various ways of attaching the PMT's to the light guides in light of the need to replace tubes in the future if rates are what we expect.

  • optical glue (epoxy?): Paul is using this now. He reports success separating the PMT's from the light guides and re-establishing good optical contact.
  • optical grease: easy to detach the tube, harder to support mechanically
  • optical cookie: same comment
  • RTV: Eugene reported a good experience using this with lead glass blocks and PMT's. Strong glue joint and easy damage-free un-gluing.

Clearly, we need to study the various options. Eugene will send Paul information on the RTV so that he can try that.


Mark outlined the next steps for FSU to develop a proposal for the contract:

  • Construction Manual
  • Quality Assurance Plan/Acceptance Procedures
  • Construction Schedule

We also discussed the importance of having a Construction Manager to oversee day-to-day operations. Paul said that he already had someone in mind who has experience with detector construction for high-energy experiments.