1. 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

2. Table of Contents Comments from Collaborators
Established Goals during last week
ToT Scan and Calibration
Finalized General Tuning Procedure
What’s next?
Questions

3. 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

4. Established Goals Last Week
Finalization of general tuning process
ToT Scan/Calibration
Reporting the suspected bug from the software
Successful installation of

5. 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

6. 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

7. ToT Scan (Before IF_TUNE)

8. ToT Scan (After IF_TUNE, Target ToT = 6)

9. ToT Scan (After FDAC_TUNE, Target ToT =6)

10. 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

11. 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
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

12. Final Tuning Result
Threshold Tuning (Target Threshold = 3100e)

13. Final Tuning Result
ToT Tuning (Target ToT = 6)

14. 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

15. What’s Next? Noise Scan and Crosstalk Scan?
Disabling the column 78~80?
Successful installation of by manual installation
Reproduction of entire tuning process from the scratch
Update TeV page once solid reproduction is successful

16. Questions for future Q/A