GlueX Start Counter Meeting, January 27, 2011

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Revision as of 10:51, 28 January 2011 by Marki (Talk | contribs) (Minutes)

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Location, Time

Thursday, January 27, 2011
3:30 pm EST
JLab: CEBAF Center, Room F326/7

Agenda

  1. Announcements
  2. Review minutes from previous meeting: all
  3. Start Counter News: Werner, Lei, Eric
  4. MOU plans: all

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/2011-1Q on the JLab CUE. This directory is accessible from the web at https://halldweb1.jlab.org/talks/2011-1Q/ . 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), Sascha Somov, Simon Taylor, Beni Zihlmann

Wrapping Material

The ESR sheets from FSU have still not arrived.

Materials and Construction

  • Lei reports a price of $190 a piece for the scintillator from Elgin. They will have with diamond milled edges.
  • The pieces will be sent to Plastic Craft for cutting, bending, and polishing.

Neutrons and SiPM Damage Rates

Sasha recommended that we look at Richard's [?? recent note] on the effect of SiPM dark current on the microscope counters. Some points from that note:

  • Timing resolution is not much affected by dark rate.
  • Looked at rates up to a gigahertz.
  • Photonique devices with a slow recovery rate gives fluctuation in timing resolution due to non-constant exposure to beam.
  • Hamamtsu devices have a faster recovery rate and a steadier response.

Measurements with the New SiPM

Werner and Eric reported on tests that have done the Hamamatsu SiPM that Carl Zorn sent them comparing its performance with a fine-mesh tube that Werner had on hand.

  • Timing resolution a bit disappointing
  • Tests were done with new scintillator from Elgin.
the new scintillator, with PMT

∘ light output ∘ attentuaion length • then with SiPM ∘ even with same amount of light, get factor 1.5-2 worse resolution ∘ pulse with led works well with SiPM ∘ more study needed ∘ cannot see single pe peak, pedestal is wide

50 mV signal from SiPM, amplified to 200 mV ADC uses direct signal

don't think it is the amount of light played a bit with bias voltage, nominally 71 V using what Carl ways

using cfd's

peltier element

werner will send MOU

time resolution requirement: what is it? what do we put in MOU.

E. put in purpose

W. may take some details out.

photo-detectors in a region of substantial magnetic field

sascha: use the tagger to help

total 56 K$ labor: 170 man-weeks for labor