Difference between revisions of "Spring 2019 DIRC Commissioning"

Revision as of 07:04, 15 February 2019

Expected Conditions

• Beam energy expected 11.3 GeV
• Solenoid on at 1350A
• CW Beam current:
  • Range: 50 nA - 1.2 uA. 250 MHz frequency.
  • Chopper slit shared with Hall C
  • Typical low-intensity commissioning for most of the 2 week period: 100 nA on JD70-105 (47 um diamond) or 225 nA on JD70-104 (17 μm diamond)
  • Some high-intensity running expected to test nominal 5 x 10⁷ γ/s in coherent peak: 500 nA on JD70-105 or 1.2 uA on JD70-104 (< 1 week total)
• FFB on or Position Slow Lock on (FFB doesn't operate below 50nA).
• Radiators:
  • Goniometer radiators:
    • Diamond JD70-104 (17 μm - 1.4·10^-4 R.L., 7×7 mm²) - wider rocking curve
    • Diamond JD70-105 (47 μm - 3.9·10^-4 R.L., 7×7 mm²) - good rocking curve
  • 40 μm Al radiator (44.9·10^-5 R.L.)
  • Amorphous
    • 1.64 µm Al (1.86·10^-5 R.L., see study)
    • 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 DIRC readout with general Hall D DAQ and online/offline monitoring
• Confirm cabling through HV/mask checks with LED system
• Implement reconstruction algorithm and compare data/MC: # detected photons, Cherenkov angle resolution
• Calibrate per-pixel timing offset of MAPMTs using LED system
• 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
    • Scans of fixed amorphous radiator and varied current from 50 - 300 nA

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:

• 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
• Dark rate run (15 minutes): Production DAQ configuration including LED trigger at 50 kHz(?) and LED bias = 0 V, collect 25M events.
• LED run (15 minutes): Production DAQ configuration including LED trigger at 50 kHz(?) and LED bias = 12.4 V, collect 25M events.

Datasets to acquire with integrated DAQ

Initial detector checkout

• Run numbers: 60590, 60591, 60593, 60594, 60595, 60596, 60613-60627
  • Note TAGM was not in the readout until Run 60??? as new fibers were being calibrated by Richard
• Concluded this initial checkout with observation that SSP slot 4 and 5 provide different yields, resulting from boards losing syncronization
  • Logbook entries:
  • Studies and results:

Production datasets

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

Set 1

• Data collected after check in DAQ system included which ends the run if SSP slot 4 and 5 timestamps lose synchronization.
  • Also trigger holdoff time increased to 2 us, and readout window reduced to 500 ns, see Sasha's logbook entry
• DAC thresholds set to pedestal + 100, with all HV=1000 V
• Run numbers: 60700-60738
  • Logbook entries:
  • Studies and results:

Set 2

• DAC thresholds set to pedestal + 200, with all HV=1000 V. Otherwise same conditions as Set 1.
• Run numbers: 60739-?????
  • Logbook entries:
  • Studies and results:

Set 3 (not started)

• DAC thresholds set to pedestal + 50, with all HV=1000 V. Otherwise same conditions as Set 1 and 2.
• Run numbers:
  • Logbook entries:
  • Studies and results:

Intensity scan

• For fixed threshold and HV setting, increase photon beam to high-intensity conditions (5e7 g/s in the coherent peak). This will require addition headroom on the DAQ through one (or multiple) option below:
  1. Improve firmware to include the busy from the SSP
  2. Move 3 fibers from SSP slot 5 to slot 3 to spread the load over the modules we have
  3. Maintain long trigger holdoff times to run at lower livetime, but test the detector performance at high rate

HV and threshold scans

• Similar set of HV, MAROC gain, and threshold settings as laser setup for comparison with final implementation
• Validate MAPMT characterization with both LED calibration and beam data