View source for Dec 12, 2019 Calorimeter

''<font color=red>Meeting Time: 11:00 a.m.</font>''

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=Participant Direct Lines=

* JLab Phone in CC L207 is 757-269-7084 (usual room)
* JLab Phone: in CC F326 is 757-269-6460
* Phone in the Regina Video-conference Suite is 306-585-4204
* Athens Phone: in Christina's office is 011-30-210-727-6947

= References =

# FCAL [https://logbooks.jlab.org/book/hdfcal HDFCAL log book]
# BCAL [https://logbooks.jlab.org/book/hdbcal HDBCAL log book]

= Goals for Calorimetry Group =

# Determine preliminary photon reconstruction efficiencies as a function of E, phi and theta in data and  simulation with a point-to-point precision of at least 5%.
# Measure systematics of pi0/eta mass calibration as a function of detector position to a precision of at east 5 MeV.
# Demonstrate agreement of photon reconstruction efficiency and resolution between data and simulation as a function of E, phi and theta to within 5%.

= Action Items =
[[Short term items]]:
# Take a new noise measurements of the BCAL FADC baselines (Mark and Jon) ✔️
# Evaluate effect of conversions in FCAL efficiency determination with particle gun and reactions (Richard suggestion -> Jon) ✔️
# Proposal for updating BCAL gain constants 2019 / extrapolation to higher energy (Karthik)
# Read calorimeter section of NIM paper and provide feedback (Matt)
# Complete [https://halldweb.jlab.org/wiki-private/index.php/2018_Work_Packages#Calorimetry Calorimeter work packages]

[[Long term items]]:
# From Mike's work: -cos(phi) type dependence in the data and a phi dependence at the downstream end of the bcal. See [[Sep 21, 2017 Calorimeter]] Meeting.
# FCAL: It has been noticed that the pi0 mass shifts when the LED pulser runs at high rate. This is still not understood. See [https://logbooks.jlab.org/entry/3595928 Log Entry 3595928] and references.  Several runs have been taken in raw mode.  These runs exhibit the shift in pi0 mass with LED running at 1 kHz.  There is a need to analyze these to try to determine the cause:
##50634 - FCAL Green LED: 1kHz, 29 V, Livetime is 9%, 1.7 M events
##50635 - FCAL Violet LED: 1kHz, 22 V, Livetime is 9%, 1.4 M events
##50636 - FCAL Blue LED: 1kHz, 15 V, Livetime is 9%, 1.5 M events

= Tentative Agenda =
 
# Announcements
# Action Items
# Run Updates
## FCAL
## BCAL
##* [https://halldweb.jlab.org/doc-private/DocDB/ShowDocument?docid=4285 SiPM damage report]
# Calibrations
# Monitoring- 
#*BCAL-LED update (Varun)[https://halldweb.jlab.org/wiki/images/7/75/BCAL_LED_Update.pdf]
# Efficiencies
#* [https://halldweb.jlab.org/doc-private/DocDB/ShowDocument?docid=4286 FCAL omega update]
# Simulations
## FCAL energy resolution
# NIM articles
# Any other business

= Minutes =
''Attending: Elton, Colin, Rupesh, Jon, Mark (JLab); Varun, Karthik, Ahmed, Zisis (UofR); Tolga (FIU); Sean (FSU); Matt (IU)

# Announcements
#* One more week of beam; period extended by one day into Friday morning.
# Action Items
#* See first two items discussed below
#* Karthik: Bcal gain constants are ready to upload to ccdb. Details in draft report to circulate in the next couple of days. This can be discussed offline. Elton: We should try to get these constants uploaded before the end of the year. Sean: It is a good time to come up with a plan that can be implemented systematically for future runs.
#* NIM paper: Matt will provide a paragraph to Elton for inclusion into the draft. Mark: Has read the section and feels that the performance should give Bcal and Fcal equal time. 
# Run Updates
## FCAL
##* Rocfcal1 is now working. Found many cable swaps after changing crate. These are now fixed.
##* Should find a good time to redo the labels on the Fcal crate, as they are degrading.
##* Need to swap out 10-15 bases. No spares, but 30-40 in the repair stack.
##* FCAL PDU no longer has a network connection. Could use spare BCAL PDU. Elton: need to order another to have a spare
##* Anagate Quattro on detector has required rebooting lately. May need replacing. We should consider purchasing a spare, also the anagate controller. 
##* 10-20% of the repaired bases are not delivering the expected voltages. They should be collected and shipped back to IU. Matt: Make sure that detailed diagnostic information be kept with the base.
## BCAL
##* Have two dead channels because the FADC DAC cannot be set. 
##* Have one hot channel, both in the Flash and the TDC. Likely not a pedestal or threshold if it is hot in both. 
## BCAL pedestals
##* [https://halldweb.jlab.org/doc-private/DocDB/ShowDocument?docid=4285 SiPM damage report] (Jon)
##* Data were taken to measure pedestal widths as a function of over-voltage at three temperatures (5, 10 and 18 degC).
##* Compared to data taken in 2015 and 2017
##* Mark: In subtracting the offset, one should do this in quadrature. Also, a more reliable baseline can be obtained by fitting (or averaging) the first few points.
##* The pedestal widths have increased very slightly from previous years. However they do exhibit the expected behavior for radiation damage: downstream is more affected than upstream, and inner layers are more affected than outer layers.
##* Next steps: a) Estimate approximate dose received to compare increased pedestal width with expected radiation damage. b) Continue to monitor, especially as heavier targets are used.
# Calibrations
#* FCAL (Colin). Spring 2019 PRIMEX calibration: non-linearity correction "broke everything". This is due to limited range fo data at higher photon energies (symmetric data <~ 3 GeV, instead of 4 GeV for other run periods). 
#* Need to evaluate the functional form for the non-linearity correction.
#* Matt: Should also develop a procedure to fix one photon and use the second photon for the non-linearity calibration. Without the symmetric requirement, much higher statistics is available.
#* Mark: Studies using etas, provides access to higher energies also.
# Monitoring- 
#*BCAL-LED update (Varun)[https://halldweb.jlab.org/wiki/images/7/75/BCAL_LED_Update.pdf]
#* Evaluated runs taken by Jon in raw mode that contain waveforms.
#* Shows that multi-peaked waveforms are consistent with reflections. 
#* Mark: This effect has been known for some time. Elton will provide a reference to early toy studies of this effect.
# Efficiencies
#* [https://halldweb.jlab.org/doc-private/DocDB/ShowDocument?docid=4286 FCAL omega update]
#* Follow-up on Richard's suggestion at last collaboration meeting to include multi shower events into the analysis of the photon gun.
#* Removal of 2 shower events from the photon gun evaluation makes it more comparable to the omega analysis and  increases the reported efficiency and brings it closer into agreement with the omega results. 
#* Mark: There remain discrepancies between the two evaluations at low angles (near the hole) and at large angles (outer edge), but these are likely due to resolution effects.
#* Jon: The DIRC will also likely affect these efficiency evaluations and should be studied.
# Simulations
## FCAL energy resolution (Mark)
##* New comparison of energy resolution using eta decays for the NIM paper has been produced. Both BCAL and FCAL simulations underestimate the data by a small amount (a "hair"), but are reasonably close. The updated constants are in ccdb and should improve comparisons between MC and data.
# NIM articles
#* Matt and Rebecca have a draft of their ML classification of Fcal showers to be submitted to NIM. [https://halldweb.jlab.org/doc-private/DocDB/ShowDocument?docid=4282 GlueX-doc-4282]. Comments and requests for authorship are welcome by Dec 20.
# Any other business
#* Happy Holidays!   Our next meeting will be Jan 9, 2020.