Spring 2019 DIRC Commissioning
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Contents
Expected Conditions
- Beam energy expected 11.7 GeV
- Solenoid on at 1350A
- CW Beam current:
- Range: 50 nA - 1.2 uA. 250 MHz frequency.
- Chopper slit shared with Hall ???
- Typical low-intensity commissioning expected to be 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.
- 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.)
- Goniometer radiators:
- 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
- Calibrate per-pixel timing offset of MAPMTs using LED system
- Determine geometric alignment parameters (position and angle offsets) for optical components
- Implement reconstruction algorithm and compare data/MC: # detected photons, Cherenkov angle resolution
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
-
July 16-30: Integration of DIRC crate with DAQ and initial test of readout with standalone MAPMT module (Ben, Sergey, Sasha) - August-October
-
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 (Oct 22) --- Justin
- Implementation of Translation Table in CCDB to orient (FPGA, channel ID) mapping from readout into physical pixel coordinates (X, Y) position along readout window (Nov 1) --- David, Justin, Bill
- Online and offline monitoring plugins to monitor occupancies and timing distributions (Nov 1) --- TBD
- LED occupancy and timing calibration (Nov 1) --- Yunjie
- Physics trigger occupancies and timing - possibly use TOF/FCAL as filter for tracks in different regions (Nov 1) --- TBD
- Include DIRC hit patterns in event display --- TBD
-
- October 29 - November 18 (3-week install period):
- Verify cabling and translation table with LED data (1 week after install) --- TBD
- Design unique patterns of HV and channel masks
- Collect ~100k events in each configuration to verify mapping
- 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
- Verify cabling and translation table with LED data (1 week after install) --- TBD
- November 19 - December 19 (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 (2 weeks, production overnight)
- 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 Ks
- Intensity scans (1 week, production overnight)
- Evaluate rate dependence and backgrounds for both high and low luminosity
- Scans of fixed amorphous radiator and varied current from 50 - 300 nA
- Complete integration with DAQ under low-intensity beam conditions: (1 week)
Datasets to acquire with integrated DAQ
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