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USBPIX READOUT SYSTEM USING FE-I4/A CHIP STATUS
UPDATE: TOT CALIBRATION AND FINALIZATION OF
TUNING PROCEDURE
Jimin Kim and Austin Piehl
Department of Physics
University of Washington
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Table of Contents
• Comments from Collaborators
• Established Goals during last week
• ToT Scan and Calibration
• Finalized General Tuning Procedure
• What’s next?
• Questions
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Comments from Collaborators
• Bill Quayle at LBL
• The result does look way better, but just to point out that
changing the value of Vthin_Alt_Coarse from 0 to 1 is
very rarely done
• Lea Caminada at LBL
• N/A
• David Leon at CERN
• N/A
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Established Goals Last Week
• Finalization of general tuning process
• ToT Scan/Calibration
• Reporting the suspected bug from the software
• Successful installation of 4.4.1.0
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ToT Scan and Calibration
• Charge Measurement
• Pixel Detector measures the charge corresponding to the energy lost by a particle
traversing a silicon sensor
• The charge measurement is used to differentiate hits from the noise and also, to improve
the spatial resolution of multi-pixel cluster
• The charge is collected and amplified by the charge sensitive preamplifier at FE-Chip
• Charge that is above the predefined threshold value is only recognized
• The deposited charge is measured using the recorded Time over Threshold (ToT): the
period of time during which the preamplifier output signal is above a predefined threshold
• ToT increases proportionally with the deposited charge and is digitized in clock cycles of
the module controller chip
• These digitized ToT signal is then converted to a charge value offline using functions
obtained from fit calibration data
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ToT Scan and Calibration
• ToT Calibration
• To obtain a uniform and best performance for charge measurement, ToT has to be
tuned to the right value which encompasses the charge of MIP ~ particles that are
way more energetic than MIP
• The right value of ToT should also provide a sufficient resolution
• FE-I4 has 2 parameters that are used in tuning ToT and it is based on 4-bit language
PrmpVbpf parameter is
used for global ToT
adjustment
FDAC: Global and local
feedback adjustment, is
used for pixel by pixel
ToT adjustment
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ToT Scan (Before IF_TUNE)
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ToT Scan (After IF_TUNE, Target ToT = 6)
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ToT Scan (After FDAC_TUNE, Target ToT =6)
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Finalized Tuning Procedure for FE-I4/A
• Global Tuning
• DIGITAL_TEST
• Strobe signal is fed repeatedly straight to the discriminator
• Checks digital functionality/data communication
• Also masks dead and weird pixels
• ANALOG_TEST
• Strobe signal larger than threshold is fed repeatedly into the Analog Cell
• Checks Analog functionality/data communication
• THRESHOLD_SCAN
• VCAL/PulsarDAC injects various charges repeatedly into the analog pixel cell
• Produces the histogram of mean threshold and dispersion/S-Curve of each pixel
• TOT_CALIB_VERIF
• Defined reference charge is injected repeatedly
• Produces the histogram of mean ToT and dispersion
• GDAC_TUNE
• Calibrate the global threshold value (Vthin_Alt_Fine and Vthin_Alt_Coarse) and scans
threshold for each step
• Gives the optimal value for Vthin_Alt_Fine and possibly, Vthin_Alt_Coarse
• IF_TUNE
• Calibrate global ToT value (PrmpVbpf) and scans ToT for each step
• Gives the optimal value for Prmpvbpf for global ToT adjustment
• Repeat from GDAC_TUNE until there is no change in dispersion and mean
• Usually repeated more than once
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Finalized Tuning Procedure for FE-I4/A
• Pixel Tuning
• FDAC_TUNE
• Calibrate the FDAC value of each pixel to be tuned to the desired ToT value
• Create an FDAC map to be loaded in cfg file for pixel by pixel ToT adjustment
• TDAC_FAST_TUNE
• Roughly calibrate the TDAC value of each pixel to be tuned to the desired threshold value
before the Fine tuning
• Create an TDAC map to be loaded in cfg file for pixel by pixel threshold adjustment
• TDAC_FINE_TUNE
• Finely calibrate the TDAC value of each pixel to be tuned to the desired threshold value
along with threshold measurement
• Create an TDAC map to be loaded in cfg file for pixel by pixel threshold adjustment
• Repeat from FDAC_TUNE until there is no change is mean and dispersion
• Usually repeated more than once
• THRESHOLD_SCAN
• To check the final tuning result for threshold calibration
• ToT_CALIB_VERIF
• To check the final tuning result for ToT calibraion
• NOISE_SCAN
• Runs at 10Khz trigger rate
• Identifies pixels with too high noise occupancy and create mask for those pixels
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Final Tuning Result
• Threshold Tuning (Target Threshold = 3100e)
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Final Tuning Result
• ToT Tuning (Target ToT = 6)
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Short update on Software version 4.4.1.0
• David Lean’s solutions
• Make sure Multi IO board is recognized after uninstalling the old
driver
• You cannot install the new driver by right clicking on the INF file
and select install
• The INF file is NOT executable file, therefore has to be installed
manually
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What’s Next?
• Noise Scan and Crosstalk Scan?
• Disabling the column 78~80?
• Successful installation of 4.4.1.0 by manual installation
• Reproduction of entire tuning process from the scratch
• Update TeV page once solid reproduction is successful
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Questions for future Q/A