July 7, 2008 Calorimetry

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  • The meeting will be held at 10:30 am ET
  • Phone:
    • +1-800-377-8846 : US
    • +1-888-276-7715 : Canada
    • +1-302-709-8424 : International
    • then enter participant code: 39527048# (remember the "#")

Reference Documents

  1. Previous minutes: June 23, 2008 Calorimetry
  2. Schedule, Tracker and Drawings (gluex pass)
  3. Schedule


  1. Preparations for Lehman Review
  2. Reconstruction work is pending -- see 3D-rendering of geometries in the links below.
  3. Updates
    • Calibration system
    • FCAL
    • BCAL
      • preparations for fiber testing
      • SiPM
  4. Any other business


Participants: JLab: Fernando, Tim, Elke, Elton, Beni, Sasha; UofR: Zisis, Andrei; IU: Matt.

Preparations for Lehman Review
  1. Alternative readout (See also DRAFT GlueX-doc-1077)
    • Elton reviewed the draft document and results of light collection for various light guide configurations.
    • Brief summary off efficiencies: Square SiPM eff~91%, Trapezoid SiPM eff~81%, Inner FM inclined eff~64%, Outer FM inclined eff~70%, Inner FM straight upstream eff~62%.
    • Matt noted that Elton should look at their light collection studies for realistic parameters GlueX-doc-1045.
  2. Dependence of resolution on granularity GlueX-doc-659
    • All studies were for normal incidence.
    • Elton asked if anyone understood the (large) dependence of delta_z on the number of layers. Matt indicated that fits to the multiple layers and position determination may not have been used in these studies. In any case, the optimal algorithms to obtain delta_z is not yet developed.
    • Elke has done a cost comparison between the FM and SiPM options, and is about $360K more expensive, taking into account fewer electronic channels but increased cost per light detector.
  3. BCAL Geometry specifications, see Figure 3 of GlueX-doc-922
    • Note that proposed solution for covering end of the Bcsl in GlueX-doc-922 is different than in GlueX-doc-1077, and tradeoffs between ease of fabrication and light collection need to be completed. These should be added to the Action Item tracker.
    • Zisis: The increased granularity for the fine mesh (FM) option is reviewed, saturation of tubes should also be considered.
  4. BCAL Number of optical photons, see pages 4-7 of GlueX-doc-808
  5. Pi0 and eta mass resolution Physics and Calorimeter Performance Metrics Fig. 10
  6. Reconstruction work is pending -- see 3D-rendering of geometries in the links below.
    • See BCAL 4x6 readout, BCAL 3x3 readout, BCAL, CDC, FDC cables, Gap between BCAL and CDC
    • New geometries are implemeted in new xml files which will be checked into svn but with designated names.
    • Elke emphasized that some of the changes willl update the geometry to our "nominal" design, such as rerouting cables upstream. Other changes, such as various configurations for the FM pmts are alternative configurations for study only at this point. These types of changes should be kept separately so the updates to the nominal design become part of the base design, while the others are kept as study options.
    • Matt: asked if any checks have been made to see if the hits are correctly propagated through the code. (Beni: no, but will check). Also with new granularities, the reconstruction will be incorrect and new algorithms implemented to match the changed geometry.
    • Beni will make the new geometry files available to IU for reconstruction studies. Blake will start these studies this week with the help of Mihajlo and Matt.
    • Sasha asked if addtional help is needed. For now, the plan is for IU to complete the photon reconstruction studies.
  1. Calibration system
    • Zisis update for Christina: Studies are waiting for difusers. The goals and requirements for a common calibration system for all pmt based systems is not been defined. We decided that we need to dedicate a working group meeting to this topic. In preparations we need to put write down the main goals and common features (e.g. relative gain changes, stability tests, how to include TOF, start counter?, etc.)
  2. FCAL
    • Setup for studying light collection in Pb glass is being updated. New fast pulsed blue LED (sub-ns rise time) is implemented. First tests with PRIMEX type coupling shows that measurements with cookies are comparable to those with greased joints (used for previous tests).
    • Building a 3x3 array of blocks and dark box so that more than one block can be tested at a time. Readout will be with Flash ADC to continue to develop timing algorithms.
  3. BCAL
    • A20AH 3x3m2 arrays. Calibration of system at low rate (1KHz) underway. Other measurements will also be performed at +2V and +4V above breakdown. (Previous measurements were at +3V).
  4. Preparations for fiber testing
    • Elton reminded that the fiber procurement is out and we expect responses by Aug 1. The specification for absolute light output still needs to be checked with fibers in hand. We also need operational setups for testing and qualifying "standard" fibers when they are delivered from the chosen manufacturer.
    • Zisis indicated that the response in terms of number of photoelectrons to a 90Sr source will be tried toward the end of July.
    • Beni: The setup at JLab is underway. The DAQ is operational, but waiting on other parts. Expect receipt by beginning of Aug.
  5. SiPM
    • Preparation of document summarizing UofR and JLab measurements in preparation for presentation at the next SiPM phone conference (July 15).
    • Fernando is reviewing the circuit for the TIA boards for feedback next Tuesday as well.