GlueX PID Meeting, April 16, 2010

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Location, Time

Friday, April 16, 2010
2:00 pm EDT
JLab: CEBAF Center, Room F326/7
ESNet: 8542553
EVO: direct meeting link
Conference Group: 800-377-8846, participant code: 77438230
Slides: talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2010-04 on the JLab CUE (you have to be a member of the "halld" group). This directory is accessible from the web at .


  1. Announcements
  2. Minutes from the last meeting
  3. Time-of-Flight Status: Sasha O. [1]
  4. Start Counter Status: Werner Boeglin/Eric Pooser
  5. Target Status: Rory Miskimen
  6. Action Items


  • FIU: Werner Boeglin, Eric Pooser
  • FSU: Sasha Ostrovidov
  • JLab: Eugene Chudakov, Mark Ito (chair), Chris Keith, Sascha Somov, Simon Taylor
  • UMass: Rory Miskimen


  • Werner told us that they have just signed a new MOU with JLab to fund the bridge position. The search is done, an offer can be made now.

Minutes from the last meeting

We went over minutes from the March 19 meeting.

  • Werner is in the process of filling out the JLab loan agreement so that Carl Zorn can send hime a SiPM array to play with.
  • Paul Eugenio had mentioned to Mark that the FSU-JLab construction MOU was with his chair and was being discussed.

Time-of-Flight Status

Sasha O. showed some results from initial cosmic tests with an integrating ADC. The goal is to do time-walk corrections for a leading edge discriminator. He is using an CAEN VME 12-bin ADC. With a gate width of 100 ns he is seeing overlap of the signal with the pedestal value, motivating the choice of a 50 ns gate. The tube with lower efficiency has lower gain as might be expected. There is evidence of saturation of the "left" ADC channel; see the non-linearity at high pulse height in the right vs. left ADC count plot.

Target Status

Refrigerator Purchase

Chris reviewed a quote he received for the pulse tube refrigerator he described last time. He received two quotes, for 51 k$ and 57 k$ with the latter having a remote motor option (motor in a separate housing connected with a 24 in. flexible coupling). Both units include the cold head and the compressor for helium gas. The remote motor option decreases cooling power by 10% which should not be a concern. Chris has sent the quotes to Tim Whitlatch and will also send them to Eugene. The unit can be shipped 16 week after the order is received.

Construction MOU

Rory reminded us that he has received edits from Elton and Fernando. Currently there are some issues in the current draft, in particular the language about a solid target. Rory will be coming to the next collaboration meeting and plans to have some face-to-face discussions with JLab folks on the draft.

Start Counter Status

Eric introduced himself; he is new student working with Werner at FIU. Eric has been measuring light output as a fuction of distance from a Sr90 source. There is a trigger PMT under the source and a fine-mesh PMT at the end of the counter. The face of the FMPMT is directly against the scintillator. He obtains the following attenuation lengths for the various thicknesses of his scintillator samples.

Thickness (mm) Attenuation Length (mm)
2 462
3 249
5 221

Werner is puzzled about why so much light is lost and why the trend of worse attenuation length for thicker counters. The scintillator are new, from Eljen, EJ200.

Eric's next tasks are to (a) resolve these mysteries, (b) work on bending and polishing of the counters, and (c) work on a GEANT simulation of the scintillators.

Action Item Review

We looked at the list. No particular comments were generated. There are still some outstanding items from last time.

New Action Items

  • Send refrigerator quotes to Eugene. -> Chris