Difference between revisions of "Nov 24, 2008 Calorimetry"

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## Ratio of central/side hole for PMT is ~4 and for APD ~3.  Non-linearity at high light output was seen.  Light has a wider pulse for the central hole.
 
## Ratio of central/side hole for PMT is ~4 and for APD ~3.  Non-linearity at high light output was seen.  Light has a wider pulse for the central hole.
 
## Temperature instability is also a concern.
 
## Temperature instability is also a concern.
−
# Plan to use a FM PMT instead of the Burle one for better linearity.
+
## Plan to use a FM PMT instead of the Burle one for better linearity.
 
# FCAL
 
# FCAL
 +
## Jake's presentation on FCAL resolution studies (see slides above):
 +
##* LED used; channel 8 was held constant on p.11 (note its fluctuation in the right panel).
 +
## Mihajlo's presentation on approximations to the FADC timing algorithm (see slides above):
 +
##* Delta_T_50 black curve us real distribution with bifurcated Gaussian fit; p.4. oscillations are ≤ 2% but he will try to do better.
 +
##* Discussion with Chris' crew: subject was programming into the FPGA sqrt(-lnx) as a lookup table versus an approximation.  Studies need to be done (6 months from now based on the time table) to see which method is more efficient. It is a chip memory vs calculation issue.  Mihajlo suggested another option: store three nos (peak amplitude, x1, x2) and analyze the timing offline (reduces chip load).  IU aims at a NIM article from their FADC work.
 
# BCAL
 
# BCAL
 
# rest of minutes are in the pipeline...  ZP
 
# rest of minutes are in the pipeline...  ZP

Revision as of 21:48, 26 November 2008

NEW TIME Time: 11:15 ET.

  • Phone:
    • +1-800-377-8846 : US
    • +1-888-276-7715 : Canada
    • +1-302-709-8424 : International
    • then enter participant code: 39527048# (remember the "#")

Items for followup from Oct 27 meeting

  1. Updates on Calibration Specification Table.
  2. Resolution studies (Blake)
    • Develop criteria for evaluating resolution studies
    • Study impact of inactive material at the end of Bcal on acceptance.
  3. Add F100 rad hard glass to simulation. - New graduate student has been assigned this project.
  4. Add roadmap for Bcal Roadmap to wiki (Elton)
  5. Check what configuration (thresholds, step sizes, stack? parameters for secondaries, etc) is being used for the Hall D simulations (Regina)
  6. Updated schedule with new Fcal procurement dates. (Elke will send this to Matt)
  7. Report on the Bfield components in the region of the Bcal reaout (JLab for next meeting).
  8. Updated drawings of Bcal modules (including O-ring) for discussions. Tim will see if that can be fitted into designer tasks.

Documents to Review

  1. Calibration/monitoring update Athens: Media:APD_vs_tube_linearity.ppt
  2. For components of the magnetic fields see GlueX-doc-912, Figures 9 and 11.
  3. APD Material for Serguei's presentation: [1],[2],[3]

Tentative Agenda

  1. Announcements
  2. Calibration
  3. FCAL
    • Report of timing studies with pmts and time calibration (Jake Bennet) [PDF slides]
    • Approximations of the sqrt( -ln( x) ) function for the timing algorithm (Mihajlo): [T50 expansion]
    • Discussion with C. Cuevas & Co.
  4. BCAL
    1. BCAL readout
    2. Resolution studies
    3. BCAL Construction MOU
    4. SiPM progress
    5. Readout
      • Review of use of APDs for readout -- see material in 'Documents to Review' above (Serguei)
      • Magnetic Field Update (JLab)?
  5. Any other business

Minutes

Attending: Fern, Hai, Ben, Ed, Chris, Elke, Serguei, Beni, Elton (JLab), Claire, Mihajlo, Jake, Matt (IU), Will (Chile), Christine (Athens), George, Andrei, Blake, Zisis (Regina)

  1. Followup items:
    1. No new updates to Calibration table, but this will be revisited in December.
    2. Resolution studies: see Blake's update below.
    3. F100 glass: in progress.
    4. Roadmap looks fine. Zisis and George went over it and have nothing to add.
    5. Hall-D simulations and configuration: in progress.
    6. FCAL procurement schedule: Matt and Elke are working on this offline.
    7. BCAL BField report: postponed to Dec 8 meeting.
    8. BCAL drawings: special meeting schedules for Dec 2.
  2. Calibration/Monitoring System: (see above link for PPT presentation). Christine gave us the highlights.
    1. Much work has been done in trying to suppress noise from the IU laser (used at 2 pulses/sec). The laser is also somewhat unstable in intensity (the Burle 8575 PMT also); Matt confirmed this from E852 experience, and added that the beam spot also tends to walk. Matt will try to dig up more info if available.
    2. Ratio of central/side hole for PMT is ~4 and for APD ~3. Non-linearity at high light output was seen. Light has a wider pulse for the central hole.
    3. Temperature instability is also a concern.
    4. Plan to use a FM PMT instead of the Burle one for better linearity.
  3. FCAL
    1. Jake's presentation on FCAL resolution studies (see slides above):
      • LED used; channel 8 was held constant on p.11 (note its fluctuation in the right panel).
    2. Mihajlo's presentation on approximations to the FADC timing algorithm (see slides above):
      • Delta_T_50 black curve us real distribution with bifurcated Gaussian fit; p.4. oscillations are ≤ 2% but he will try to do better.
      • Discussion with Chris' crew: subject was programming into the FPGA sqrt(-lnx) as a lookup table versus an approximation. Studies need to be done (6 months from now based on the time table) to see which method is more efficient. It is a chip memory vs calculation issue. Mihajlo suggested another option: store three nos (peak amplitude, x1, x2) and analyze the timing offline (reduces chip load). IU aims at a NIM article from their FADC work.
  4. BCAL
  5. rest of minutes are in the pipeline... ZP
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