Difference between revisions of "Fall 2019 DIRC Commissioning"

Revision as of 05:55, 24 October 2019

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

• January 2-10: Integration of DIRC crate with DAQ and initial test of readout with standalone MAPMT module (Ben, Sergey, Sasha)
• January 7-30 (Software Development)
  • Implementation of DAQ decoder for SSP data format in sim-recon to create low level hit objects (David)
  • Calibration document with expected tables for CCDB (Jan 7) --- Justin
  • Implementation of Translation Table in CCDB to orient (FPGA, channel ID) mapping from readout into physical global pixel # along readout window (Jan 4) --- David, Justin
  • Online and offline monitoring plugins to monitor occupancies and timing distributions (Jan 7) --- Justin
    • LED occupancy and timing calibration (Jan 14) --- Yunjie
    • Physics trigger occupancies and timing (Jan 30) --- Justin
    • Include DIRC hit patterns in event display (Jan 30) --- Roman, Thomas
• January 14-30 (2-week testing period):
  • Verify cabling and translation table with LED data (Jan 22-30) --- TBD
    • Design unique patterns of HV and channel masks
    • Collect ~100k events in each configuration to verify mapping
  • Implement LED trigger into DAQ --- Ben, Sasha
    • Detemine optimal LED conditions (amplitude and trigger rate) to be added to production trigger --- TBD
  • HV and threshold scans with LED data (2 weeks after install) --- TBD
    • Duplicate scans of HV and thresholds as used in laser test setup (see below)
    • Determine initial HV and threshold settings for LED and beam data
  • Initial time offset calibrations with LED data (3 weeks after install) --- Yunjie
• January 30 - February 12 (commissioning with beam):
  • Complete integration with DAQ under low-intensity beam conditions: (1 week)
    • Evaluate scaler rates and distributions relative to MC predictions
    • Mask any noisy channels for production data
    • Determine what global parameters can be optimized (beam current, bar box position, etc.) can be optimized
  • Production data taking with all sub-detectors in nominal condition (1 week, standard production)
    • FCAL-BCAL production physics trigger with interleaved DIRC LED and random triggers
    • Collect sufficient statistics for optical alignment with identified ρ and φ, as well as more exclusive reactions with tagged K_s
  • Intensity scans (2 days)
    • Evaluate rate dependence and backgrounds for both high and low luminosity

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
   • See instructions on Operations Wiki
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.

Production datasets

• Expect to collect ~1 billion events for each configuration to reasonably compare photon yield and hit time resolutions. We expect these datasets should all be usable the total statistics needed in single photon Cherenkov angle resolution and detector alignment studies.

Low-intensity Set

Moderate-intensity Set

• DAC thresholds set to pedestal + 50, with all HV=1000 V. Beam current = 450 nA with 17 um diamond
• Run numbers: 60789-60799, ~1.1 billion triggers

High-intensity tests

• Goal: Increase photon beam as close to high-intensity conditions (5e7 g/s in the coherent peak). This corresponds to ~900 nA on the 17 um diamond and a ~90 kHz trigger rate
• DAC thresholds set to pedestal + 100, with all HV=1000 V.
• Requirements:
  • Lower drift chamber HV (Beni/Lubomir)
  • Turn off HV for 4 inner TOF paddles (Beni)
  • Turn off HV for TAGH counters below microscope (Sasha)
  • Tune trigger/DAQ settings (Sasha/Sergey)
• Run numbers:
  • First attempt between 700-800 nA: 60811-60829, ~1 billion events
  • Later attempt between 550-700 nA 60838-60841, ~0.16 billion events. Couldn't run at highest beam current due to increased trigger rate compared to first attempt on Sunday
• Logbook entries:
  • Intensity scan summary
  • TOF scalar rate summary
  • Drift chamber summary

DIRC LED skims

/cache/halld/RunPeriod-2019-01/calib/ver01/DIRC-LED

Additional studies

Magnetic Field Study During Solenoid Magnet Ramping

• To monitor the DIRC occupancy variation under magnetic fields, we ran the LED pulser runs throughout the magnet ramp. Runs are taken with the LED bias = 12.4 V with the pulser running at 5 kHz for all but the first 2 runs in the scan. All HV=1000V, MAROC gains equalized (version 1) and DAC thresholds set at pedestal + 100.