Fall 2019 DIRC Commissioning

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Fall 2019 Commissioning Meetings

Expected Conditions

  • Beam energy expected 11.6 GeV
  • Solenoid on at 1350A (except for straight track runs)
  • CW Beam current:
    • Range: 50 nA - 600 nA. 250 MHz frequency.
  • Expect to take commissioning datasets at:
    • Low-intensity: 100 nA on 50 um diamond
    • Moderate-intensity: 200 nA on 50 um diamond
    • High-intensity (GlueX-II): 300 nA on 50 um diamond
  • FFB on or Position Slow Lock on (FFB doesn't operate below 50nA).
  • Radiators:
    • Goniometer radiators:
      • Several 50 μm diamonds (4·10-4 R.L., 7×7 mm²)
      • 40 μm Al radiator (44.9·10-5 R.L.)
    • Amorphous
      • 1.64 µm Al (1.86·10-5 R.L)
      • 10 µm Al (11.2·10-5 R.L.)
      • 30 µm Al (33.7·10-5 R.L.)
  • Tagger quadrupole on (-4.2 A).
  • Collimator hole: 5 mm diameter
  • Targets: LH2 cryogenic target

Commissioning Goals

  • Integrate North and South Optical box readout with general Hall D DAQ and online/offline monitoring at GlueX-II intensities
  • Implement reconstruction algorithms and compare data/MC: # detected photons, Cherenkov angle resolution
  • Calibrate per-pixel timing offset of MAPMTs using LED system
  • Determine tracking position and angle resolution at DIRC using GEM/TRD detectors
  • Determine geometric alignment parameters (position and angle offsets) for optical components

Commissioning Observables

  • "Ring" images for tracks with fixed kinematics (binned in position space over bars) overlaid on MC distributions
  • Per-pixel timing and Cherenkov angle differences (measured - LUT expected) to confirm geometry
  • Number of detected photons/track
  • Single photon resolution (SPR) per pixel

Commissioning Timeline, Tasks and Milestones

  • October 25 - December 2:
    • Mirror box assembly and installation
    • LED SiPM reference (still needs to be read out by fADC and TDC)
    • LED runs with threshold and HV scans
      • Duplicate scans of HV and thresholds as used in laser test setup
    • LED rate scans to test readout rate limitations (Ben/Sasha)
      • Any reduction in data size to be achieved with header reduction, etc.?
  • December 2 - 5 (commissioning with beam):
    • Initial trigger and detector checkout
    • Initial straight track runs for all 3 TRD/GEM positions
  • December 5 - December 20 (commissioning with beam):
    • Complete integration with DAQ under low-intensity beam conditions: (1 day)
      • Evaluate scaler rates and distributions relative to MC predictions for both North and South OBs
    • Production data taking with all sub-detectors in nominal condition (10 days, estimate from Spring 2019)
      • FCAL-BCAL production physics trigger with interleaved DIRC LED and random triggers
      • Includes GEM/TRD detectors with flash 125 readout in tracking mode
      • Collect sufficient statistics for optical alignment with identified ρ and φ, as well as more exclusive reactions with tagged Ks
    • Full GEM readout datasets (tracking mode) with all other sub-detectors in nominal condition (3 days)
      • Requires change of detector position while field is on
    • Full GEM readout datasets (cluster counting mode) with all other sub-detectors in nominal condition (2 days)
      • Single detector position will be used with GEM/TRD in special readout mode with Xe gas
  • Some additional tasks for GlueX-II commissioning (not necessarily DIRC related and could be interleaved with the tasks above)
    • Align multiple diamonds in goniometer for Spring running
    • DAQ/trigger tuning for GlueX-II intensity
    • TOF2 detector checkout and calibration

Calibration datasets

Summary page for Fall 2019 TRD/GEM Commissioning lists the relevant run ranges for the datasets collected below

Straight-track data

  • For alignment of the GEM/TRD we need to acquire production samples with the magnetic field off
  • Straight-track sample at each of the 3 TRD positions with the full GEM readout for tracking and alignment studies

Full GEM readout: tracking mode

  • The electronics for three of the GEM packages are readout limited to ~3kHz
  • At least one large dataset at each of the 3 TRD positions will be required with the full readout for tracking and alignment studies with the full solenoid field

Full GEM readout: TRD mode

  • The electronics for three of the GEM packages are readout limited to ~3kHz
  • For one position, a large dataset should be acquired with the TRD in "cluster counting" mode with all the GEM packages read out.

Raw mode readout

  • No requirement for DIRC but other detectors may need raw mode readout periodically.

Production datasets

  • Expect to collect at least ~1 billion events for each configuration (10 in total) to reasonably compare photon yield and hit time resolutions. We expect these datasets should all be usable for the total statistics needed in single photon Cherenkov angle resolution and detector alignment studies.
  • At each intensity collect dataset for 3 different DIRC threshold settings.
  • The GEM (single package) and Wire TRD are readout by the flash 125 and should be included in the production running (in tracking mode with Ar gas), which should operate at all the intensity settings described below.
    • Two other GEM detector packages are readout by APV and are rate limited to ~5kHz and will be included only in calibration datasets described above.
    • Need production datasets at each of the 3 TRD/GEM positions, but only for one intensity/threshold setting.

Low-intensity Set

Nominal conditions: beam current = 150 nA with 50 um diamond or 4.5e-5 amorphous

  • Nominal DIRC setting: DAC = pedestal + 100, HV = 1000V, equalized gain v1 (equalizeVer1_DAC100_Pedestal70495.cnf)
    • Runs: 70937-70942, 70964-70974, 70993-71006, 71027-71037, 71071-71079, 71103-71111
    • Total triggers = 3.8 billion
  • Low threshold setting: DAC = pedestal + 50, HV = 1000V, equalized gain v1 (equalizeVer1_DAC50_Pedestal70495.cnf)
    • Runs: 71038-71060
    • Total triggers = 2.6 billion
  • Minimum gain 64 setting: DAC = pedestal + 100, HV = 1000V, equalized gain v2 (equalizeVer2_DAC100_Pedestal70495.cnf)
    • Runs: 71112, 71113, 71125, 71126, 71161
    • Total triggers ~ 0.5 billion
  • Unity gain setting: DAC = pedestal + 100, HV = 1000V, unity (unityGain_DAC100_Pedestal70495.cnf)
    • Run 71162-71165
    • Total triggers ~ 0.6 billion
  • Low HV setting: DAC = pedestal + 100, HV = 950V, equalized gain v1 (equalizeVer1_DAC100_Pedestal70495.cnf)
    • Run 71166, 71224, 71225
    • Total triggers ~ 0.5 billion
  • High HV setting: DAC = pedestal + 100, HV = 1050V, equalized gain v1 (equalizeVer1_DAC100_Pedestal70495.cnf)
    • Run 71226-71228
    • Total triggers ~ 0.5 billion

High-intensity production

  • Goal: Increase photon beam to GlueX-II intensity conditions (5e7 g/s in the coherent peak).
  • Beam current = 300-350 nA with 50 um diamond and amorphous radiator
    • Run 71229-71235 and 71239-71242
    • Total triggers ~ 1.6 billion
  • DAC thresholds set to pedestal + 100, with all HV=1000 V.
  • Additional Requirements:
    • Lower drift chamber HV (Beni/Lubomir)
    • Turn off HV for TAGH counters below microscope (Sasha)
    • Tune trigger/DAQ settings (Sasha/Sergey)

LED runs

  • Goal: Study single photon performance for various HV and threshold settings
  • Data included LED SiPM reference signal for all runs

Daily Tasks during commissioning

The tasks described here require no beam in the Hall (collimator in blocking position). These should be completed each day to monitor PMT performance over the course of commissioning and should be done during scheduled beam downtimes if possible:

  1. Threshold scan (15 minutes): Special DAQ configuration run at pre-start to scan DAC thresholds and record scaler rates to monitor pedestals for all channels
  2. Dark rate run (15 minutes): Production DAQ configuration including LED trigger at 5 kHz and LED bias = 0 V, collect 5M events.
  3. LED run (15 minutes): Production DAQ configuration including LED trigger at 5 kHz and LED bias = 12.4 V, collect 5M events.

DIRC LED skims


Additional studies

Magnetic Field Study During Solenoid Magnet Ramping

  • To monitor the DIRC occupancy variation under magnetic fields, we will run the LED pulser runs throughout the magnet ramp. Runs should be taken with the LED bias = 12.4 V with the pulser running at 5 kHz. All HV=1000V, MAROC gains equalized (version 1) and DAC thresholds set at pedestal + 100.