Baby BCAL at JLab

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This page summarizes JLab work with the baby BCAL in 2023 for the EPIC (EIC) Barrel EM Calorimeter 

Note that we agreed to use the name "Baby BCAL" in June 2023. Previously one may encounter use of the name "mini BCAL" as well.

Photos & Sketches

March 2023 Beam Tests

Goals and Hall D PS Setup

Main Goals

  1. Demonstrate the Baby BCAL setup works
  2. Measure resolution at 3-6 GeV to better constrain the constant portion of resolution function
  3. Extract number of photoelectrons/GeV with well understood beam conditions


Logbook Entries

Notable Configuration Changes

(not necessarily complete)

  • Good runs start at 121050. There may be issues with data quality earlier on. Energy coverage: roughly 3.2-4.5 GeV and 5.6-5.9 GeV.
  • SciGlass moved: 121197 and after. Energy coverage: roughly 3.2 - 5.2 GeV.
  • BBCAL rotated runs 121210 and after
  • Straight track config & AMO radiator: 121212-end
  • SiPM biases:
    • From logbook entries, these probably need to be double checked
    • 75 upstream, 74 V downstream 121050-121209
    • 75 upstream, 73.5 V downstream 121210
    • 75.5 upstream, 74 V downstream 121211
    • 75 upstream, 73.5 V downstream 121212-end

Run Log

  • Raw Mode:
    • Run 121209 (75 and 73.5 V SiPM bias)
    • Run 121210 (75.5 and 74 V SiPM bias)
    • Runs 121208, 121213 and 121215 are also raw mode config according to RCDB, but no notes on BBCAL config found in logbooks.
  • Bad runs (March 2023):
    • 121049 (slow time dependence, BBCAL may have just been turned on and not quite at equilibrium temp)
    • 121197 (channel S10 jumpy for unknown reasons)

Cosmic Tests, started August 2023


We attempted to use as close to the same configuration as in March 2023 as possible. Below is a list of cabling and configurations.

Note: North=Downstream, South=Upstream. North is now closer to the collimator cave, and South is closer to the solenoid.
  • The two PS counters delivered about 2 Hz counting rate in an OR mode, when they were one on top of the other (and both under the Baby BCAL). When they moved to just above and just below the Baby BCAL, the count rate is sub-Hz, maybe 1/3 Hz or so.

Baby BCAL by the numbers

  • Cooling connector distance 38” Each cooling connector 7.5” beyond SciFi end
  • End to end SiPMs 34”
  • End to end handles 36”
  • Trim trio to end of black connectors 39”
  • Cable allowances 45-46”
  • Wedge width is 3.5” at the top aluminum plate and 4.5” at the bottom
  • 21 3/4 from top plate at step
  • Total length between aluminum top plate step 27.5 x 2 cm
  • Sketch: Media:BabyBCALsketch.png

Photos (Google Drive)

See here:

Logbook Entries

SiPM Modules

  • Used upstream & downstream modules 49 in their corresponding up/down sides (as labeled on baby BCAL)
    • Upstream module plugged into J7, downstream into J8 to match March 2023 config.
    • Standard LV=5 V setting for low voltage power to modules
    • Upstream bias voltage = 75 V, downstream bias voltage = 74 V (to match start of March 2023 conditions). See logbook entry for later voltage settings:
    • Scripts to turn bias and LV on/off can be found on gluon machines at: /gluonfs1/home/hdops/bcal_cosmic/august2023/
  • Cabling: same as March 2023. Lemo cables labeled AS0-AS15 and AN0-AN15. These are plugged into crate U1-7-TOP (crate number 94 in software). Slot 7 is north, slot 8 is south (indexes 0-15 in slot match A(S/N)0-15).

Run Log

  • Spreadsheet for run tracking (both March PS and Fall Cosmics)
  • Raw Mode:
    • Runs 121302-121308, inclusive, have raw+pulsed mode at different biases. Links are above, and summarized here.
    • Run 121312: first run using chiller. See e-log entry.

Analysis - Sasha/Karthik/Zisis

  • Directories for Baby BCAL Cosmics Analysis: (on hdops)
    • /gluonfs1/home/hdops/bbcal with 2 subdirectories:
    • glass_prototype: code to make ROOT files for cosmics analysis; use (in this dir)
    • display: code to parse through events and saw raw more pulses; use (in this dir)
  • Command for environment: source setenv.csh / see setenv HALLD_MY ..display under HDDS section of setenv.csh and the very last line of that file which has source /gluex/etc/hdonline.cshrc; Sasha used those two to nail the ENV variables
  • Commands for building: scons -c / scons -u install
  • Command for creating ROOT tree: hd_root -PPLUGINS=glass_prototype -o bbcal.root /gluonraid5/data4/rawdata/active/RunPeriod-2023-01/rawdata/Run121303/*.evio
  • ROOT tree: contains raw amp_n, pulsed pulse_int_n, pulse_amp_n, pulse_ped_n, and ch_n, t_n. n is 1-16 for North, and 17-32 for South.
  • Analyzed runs: runs 121302-121308, inclusive, have good data and were analyzed with thr=0 and thr=110 for the threshold.
  • ROOT files names: bbcal_Run121301_thr000.root, bbcal_Run121301_thr100.root, etc. These are in the glass_prototype directories and two other spots (Zisis' JLab account homedir and on Zisis' laptop.
  • Analysis needs more checking as not all results make sense (comment as of Sept 28, 2023, by ZP). It was purely a solid angle coincidence between the PS trigger counters; see e-log entry.

Analysis - Jon

  • Analysis plugin on JLab farm: /home/jzarling/work/HALLD_MY/miniBCAL_EIC/ and /work/HALLD_MY/miniBCAL_EIC_RawMode/
  • Analysis plugin on gluon machines: /gluonfs1/home/hdops/bcal_cosmic/babyBCAL_EIC
  • Occupancy check:
    • Assuming you are logged onto a gluon machine (or anywhere behind JLab's firewall hallgw) do:
    • ssh hdops@gluon47
    • cd /gluonfs1/home/hdops/bcal_cosmic/babyBCAL_EIC
    • Use script run_on_testfile and run number (e.g. ./run_on_testfile 121302 in the same folder as the plugin. This will run the plugin and create two png files in the same directory with occupancies for each channel.
  • First Look at Calibrated BCAL