Difference between revisions of "Dec 8, 2008 Calorimetry"

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#* Develop criteria for evaluating resolution studies  
 
#* Develop criteria for evaluating resolution studies  
 
#* Study impact of inactive material at the end of Bcal on acceptance.
 
#* Study impact of inactive material at the end of Bcal on acceptance.
−
# Add F100 rad hard glass to simulation. - New graduate student has been assigned this project.
+
#* Check what configuration (thresholds, step sizes, stack? parameters for secondaries, etc) is being used for the Hall D simulations (Regina)
−
# [[BCAL#Roadmap_toward_a_decision_for_Bcal_Readout | Add roadmap for Bcal Roadmap to wiki]] (Elton)
+
−
# Check what configuration (thresholds, step sizes, stack? parameters for secondaries, etc) is being used for the Hall D simulations (Regina)
+
−
# Updated schedule with new Fcal procurement dates. (Elke will send this to Matt)
+
 
# Report on the Bfield components in the region of the Bcal reaout (JLab for next meeting).
 
# Report on the Bfield components in the region of the Bcal reaout (JLab for next meeting).
−
# Updated drawings of Bcal modules (including O-ring) for discussions. Tim will see if that can be fitted into designer tasks.
 
  
 
= Documents to Review=
 
= Documents to Review=
−
# Calibration/monitoring update Athens: [[Media:APD_vs_tube_linearity.ppt]]
+
# Calibration/monitoring update Athens (old version): [[Media:APD_vs_tube_linearity.ppt]]
−
# Testing of fibers with Sr90 source (Beni)
+
# Calibration/monitoring update Athens (updated): [[Media:APD_vs_tube_linearity2.ppt]]
 +
# Calibration/monitoring update Athens: [[Media:Threshold.ppt]]
  
−
= Tentative Agenda =
+
= Tentative Agenda (Emphasis is Calibration) =
  
 
# Announcements
 
# Announcements
 
# Calibration
 
# Calibration
 
#* Progress on filling in the [[Sep 2, 2008 Calorimetry#Calibration Specifications Table | Calibration Specification Table]].
 
#* Progress on filling in the [[Sep 2, 2008 Calorimetry#Calibration Specifications Table | Calibration Specification Table]].
−
# FCAL
+
# FCAL Update
−
#* Report of timing studies with pmts and time calibration (Jake Bennet) [[http://dustbunny.physics.indiana.edu/~mashephe/fcal_fadc_24Nov.pdf PDF slides]]
+
−
#* Approximations of the sqrt( -ln( x) ) function for the timing algorithm (Mihajlo): [[http://dustbunny.physics.indiana.edu/~mikornic/GlueX/T50expand.pdf T50 expansion]]
+
−
#* Discussion with C. Cuevas & Co.
+
 
# BCAL
 
# BCAL
−
## [[BCAL#Roadmap_toward_a_decision_for_Bcal_Readout| BCAL readout]]
+
## [[Fiber Test with SiPM | Testing of fibers with SiPM readout and Sr90 source]] (Beni)[http://www.jlab.org/~zihlmann/fibertest/ScintillationFiberTestsatJlab.ppt Talk]
−
## [[Resolution studies]]
+
## [https://halldweb.jlab.org/doc-private/DocDB/ShowDocument?docid=1130 Lead Specification] (Elton)
−
## BCAL Construction MOU
+
## Magnetic Field Update (JLab)
−
##* [[Oct 15, 2008 Calorimetry | BCAL Construction Docs & Action Items]]
+
## Other updates
−
## SiPM progress
+
### if time: [[Resolution studies]]
−
## Readout
+
−
##* Review of use of APDs for readout -- see material in 'Documents to Review' above (Serguei)
+
−
##* Magnetic Field Update (JLab)?
+
 
# Any other business
 
# Any other business
  
 
=Minutes=
 
=Minutes=
−
Attending: Fernando, Hai, Ben, Ed, Chris, Elke, Serguei, Beni, Elton (JLab), Claire, Mihajlo, Jake, Matt (IU), Will (Chile), Christine (Athens), George, Andrei, Blake, Zisis (Regina)
+
Attending: Athens: George Voulgaris, Christina; JLab: Tim, Fernando, Beni, Elke, Elton; FSU: Alex; UofR: Blake, Zisis, George, Andrei; IU: Matt (please add others if present)
  
−
# Followup items:
+
# Announcements
−
## No new updates to Calibration table, but this will be revisited in December.
+
#* Elton will attend Sendai08 to present some Hall B data and will take advantage of trip to visit Kuraray.
−
## Resolution studies: see Blake's update below.
+
# Calibration
−
## F100 glass: in progress.
+
#* No updates on the calibration table requirements. Alex indicated that FSU will review the table and give feedback as testing on TOF detectors proceeds.
−
## Roadmap looks fine.  Zisis and George went over it and have nothing to add.
+
#* George V. reviewed the two posted presentations, one on pmt and APD linearity and the second on LED thresholds.
−
## Hall-D simulations and configuration: in progress.
+
#* First, radiated noise from laser reduced using a Faraday cage. Remaining background levels in APD spectra (50 mV) reduced to 2 mV using various stages of shielding.
−
## FCAL procurement schedule: Matt and Elke are working on this offline.
+
#* Linearity of APD established by comparing to LED. Comparing pmt to LED, determined range of "overlinearity". After correction for this non-linearity, the measured response ratio between pmt and APD is 3.3/3.2.
−
## BCAL BField report: postponed to Dec 8 meeting.
+
#* Conclusion: APD is useful device for calibration. In comparisons with PMT, Elke cautioned that one is comparing different active areas as well as different gains.
−
## BCAL drawings: special meeting schedules for Dec 2.
+
#* Christina: Main goals at present ar to compare linearity and time stability.
−
# Calibration/Monitoring System: (see above link for PPT presentation).  Christine gave us the highlights. 
+
#* Zisis: Inquired about future measurements with SiPMs? Yes, that is the plan. Also, the fine mesh PMT will be studied.
−
## 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.
+
#* For LEDs, additional studies are required on temperature and time stability
−
## 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.
+
#* Elke: Should review existing literature and other detectors as basis for planning design. Christina, said that indeed a review of literature has been conducted and most systems either use lasers with optical benches (expensive), or moving toward LEDs, which they are presently investigating.
−
## Temperature instability is also a concern.
+
#* Christina: most of the laser tests have been completed, they are now concentrating on LED tests.
−
## Plan to use a FM PMT instead of the Burle one for better linearity.
+
#* Elton asked what were the driving inputs that are required to design the calibration system. George V.: dynamic range is one of the major factors. Fernando: His experience is that LEDs vary considerably in output (even from the same batches) and recommended testing a larger sample to investigate variation in light output.
−
# FCAL
+
# FCAL Update
−
## Jake's presentation on FCAL resolution studies (see slides above):
+
#* No update
−
##* 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 is the 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 values (peak amplitude, x1, x2) and analyze the timing offline (reduces chip load).  IU aims at a NIM article from their FADC work.
+
 
# BCAL
 
# BCAL
−
## Blake's Resolution studies (see sldies above)
+
## [[Fiber Test with SiPM | Testing of fibers with SiPM readout and Sr90 source]] (Beni)[http://www.jlab.org/~zihlmann/fibertest/ScintillationFiberTestsatJlab.ppt Talk]
−
##* He is in his initial step on these studies and is getting a handle on how the quantities in the ROOT tree relate to each other; these plots show photons hitting either calorimeter. Elke suggested that the study focus initially on both photons in the BCAL.
+
##* Summary of light output at three differenct distances using pmts and SiPMs for Bicron and Kuraray fibers. All summarized on wiki. Beni will consolidate into a GlueX-doc note and post on the portal.
−
##* George reported on the construction MOU corrections; they will be sent to JLab soon. Also, the UofR is nearing the final decision on the overhead rates.
+
##* Andrei inquired about the subtraction of non-source triggers in the SiPM measurement. Under question was the ratio of cosmic-ray triggers vs. pmt dark rate. Beni indicated that the correction was only 20%, so it could not affect the conclusions very much. However, it will be quantified further.
−
##* George reported that Kathryn is continuing the SiPM tests with the TIA boards. The pulses look nice without overshoot but the gain is too low, and measurements will continue using an external x10 amp.
+
##* Zisis asked about the differences between this measurement and the spectophotometer measurements. This is likely due to the assumed PDE function for the SiPMs (about 13%) used in the interpretation of the spectrophotometer measurements.  
−
##* Alternate readout option: APD (see Serguei's slides from above).  The energy resolution (5%/sqrt(E)+1% looks too high for such a device. The APDs need temp stabilization using a water chiller. QE is very high (80-90%). Gain is quite low.  A comparison table to other readouts is at the end of his slides.  APDs for BCAL would have to deal with their noise and low gain. Elke suggested buying such units next year to run tests on them.
+
## [https://halldweb.jlab.org/doc-private/DocDB/ShowDocument?docid=1130 Lead Specification] (Elton)
−
# Next meeting on Dec 8 dedicated mostly to Calibration/Monitoring.
+
##* There has been an iteration on the Pb spec with George and Zisis. A close to final spec has been posted on the portal. Tim will get feedback from vendors about the difficulty in supplying specific lead sheets sizes.
 +
# Nex time:
 +
## Magnetic Field Update (JLab)
 +
## [[Resolution studies]]

Latest revision as of 17:08, 24 February 2017

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 Nov 24 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.
    • Check what configuration (thresholds, step sizes, stack? parameters for secondaries, etc) is being used for the Hall D simulations (Regina)
  3. Report on the Bfield components in the region of the Bcal reaout (JLab for next meeting).

Documents to Review

  1. Calibration/monitoring update Athens (old version): Media:APD_vs_tube_linearity.ppt
  2. Calibration/monitoring update Athens (updated): Media:APD_vs_tube_linearity2.ppt
  3. Calibration/monitoring update Athens: Media:Threshold.ppt

Tentative Agenda (Emphasis is Calibration)

  1. Announcements
  2. Calibration
  3. FCAL Update
  4. BCAL
    1. Testing of fibers with SiPM readout and Sr90 source (Beni)Talk
    2. Lead Specification (Elton)
    3. Magnetic Field Update (JLab)
    4. Other updates
      1. if time: Resolution studies
  5. Any other business

Minutes

Attending: Athens: George Voulgaris, Christina; JLab: Tim, Fernando, Beni, Elke, Elton; FSU: Alex; UofR: Blake, Zisis, George, Andrei; IU: Matt (please add others if present)

  1. Announcements
    • Elton will attend Sendai08 to present some Hall B data and will take advantage of trip to visit Kuraray.
  2. Calibration
    • No updates on the calibration table requirements. Alex indicated that FSU will review the table and give feedback as testing on TOF detectors proceeds.
    • George V. reviewed the two posted presentations, one on pmt and APD linearity and the second on LED thresholds.
    • First, radiated noise from laser reduced using a Faraday cage. Remaining background levels in APD spectra (50 mV) reduced to 2 mV using various stages of shielding.
    • Linearity of APD established by comparing to LED. Comparing pmt to LED, determined range of "overlinearity". After correction for this non-linearity, the measured response ratio between pmt and APD is 3.3/3.2.
    • Conclusion: APD is useful device for calibration. In comparisons with PMT, Elke cautioned that one is comparing different active areas as well as different gains.
    • Christina: Main goals at present ar to compare linearity and time stability.
    • Zisis: Inquired about future measurements with SiPMs? Yes, that is the plan. Also, the fine mesh PMT will be studied.
    • For LEDs, additional studies are required on temperature and time stability
    • Elke: Should review existing literature and other detectors as basis for planning design. Christina, said that indeed a review of literature has been conducted and most systems either use lasers with optical benches (expensive), or moving toward LEDs, which they are presently investigating.
    • Christina: most of the laser tests have been completed, they are now concentrating on LED tests.
    • Elton asked what were the driving inputs that are required to design the calibration system. George V.: dynamic range is one of the major factors. Fernando: His experience is that LEDs vary considerably in output (even from the same batches) and recommended testing a larger sample to investigate variation in light output.
  3. FCAL Update
    • No update
  4. BCAL
    1. Testing of fibers with SiPM readout and Sr90 source (Beni)Talk
      • Summary of light output at three differenct distances using pmts and SiPMs for Bicron and Kuraray fibers. All summarized on wiki. Beni will consolidate into a GlueX-doc note and post on the portal.
      • Andrei inquired about the subtraction of non-source triggers in the SiPM measurement. Under question was the ratio of cosmic-ray triggers vs. pmt dark rate. Beni indicated that the correction was only 20%, so it could not affect the conclusions very much. However, it will be quantified further.
      • Zisis asked about the differences between this measurement and the spectophotometer measurements. This is likely due to the assumed PDE function for the SiPMs (about 13%) used in the interpretation of the spectrophotometer measurements.
    2. Lead Specification (Elton)
      • There has been an iteration on the Pb spec with George and Zisis. A close to final spec has been posted on the portal. Tim will get feedback from vendors about the difficulty in supplying specific lead sheets sizes.
  5. Nex time:
    1. Magnetic Field Update (JLab)
    2. Resolution studies
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