1. Characterization of a Pixel Sensor for ITK
In the ATLAS Pixel Group at CERN
May 5, 2017
Alina Arranhado

2. INTRODUCTION
May 5, 2017
Alina Arranhado

3. INTRODUCTION ATLAS is one of the 4 big experiments of the LHC
Phase-II upgrade aims for an increase in luminosity
ATLAS
May 5, 2017
Alina Arranhado

4. INTRODUCTION ATLAS is one of the 4 big experiments of the LHC
Phase-II upgrade aims for an increase in luminosity
Evaluating different technology options for the ATLAS Pixel ITK
Aim: Increase radiation tolerance, less power consumption, more granularity
ATLAS
Inner Tracker
Pixel Sensor
May 5, 2017
Alina Arranhado

5. SILICON DETECTOR How does a silicon detector work? May 5, 2017
Alina Arranhado

6. SILICON DETECTOR How does a silicon detector work? CMOS technology
Separate circuit for each pixel
Semiconductor material, current flows in one direction only ( diode)
Potential in opposite direction
Ionization  Electron-hole-pairs
=> electrical signal
May 5, 2017
Alina Arranhado

7. Tower-jazzTJ 180 investigator chip
LASER SETUP
Laser induced transient current technique
Device under test:
Tower-jazzTJ 180 investigator chip
Power supply / control,
data monitoring
May 5, 2017
Alina Arranhado

8. SETUP
Voltage divider
May 5, 2017
Alina Arranhado

9. MEASUREMENTS
May 5, 2017
Alina Arranhado

10. MEASUREMENTS
May 5, 2017
Alina Arranhado

11. MEASUREMENTS
Desired result: clearly defined area of high potential drop at the pixel sensor
→ localize the pixel sensor's position relative to the laser
→ detailed investigation of area of interest
Problem: defocused laser beam
→ refocus and measure beam width
May 5, 2017
Alina Arranhado

12. BEAM WIDTH Aim: measuring minimum laser beam width
 varying distance between laser and diode
Laser
Diode
(~5mm)
Beam shape
May 5, 2017
Alina Arranhado

13. RESULTS Response changes like S-shape  calculate beam width
Sensor Response (mV)
Sensor Response (mV)
𝑃 𝑋 = 𝑃𝑇𝑂𝑇 2 1− erf 𝑋−𝑋0 𝜔𝑥
Response changes like S-shape
 calculate beam width
May 5, 2017
Alina Arranhado

14. OTHER CONTRIBUTIONS
Calibration of the temperature read-out system (Voltron)
Aim: thermal characterization of ITK Stave prototypes
Voltron ID to distinguish several Voltrons
Arduino
May 5, 2017
Alina Arranhado

15. VOLTRON – CALIBRATION Use 3 reference resistors
calculate calibration constant
Plot the expected resistance vs the measured resistance
 results are very linear
May 5, 2017
Alina Arranhado

16. CONCLUSIONS Measuring beam spot shape (width) Calibration of Voltron
Understanding underlying physics
Conducting several measurements
Outlook: measure a signal from the Tower-jazz chip
analyse data of three contiguous pixels
May 5, 2017
Alina Arranhado

17. Meeting very interesting people
CONCLUSIONS
Measuring beam spot shape (width)
Calibration of Voltron
Meeting very interesting people
Understanding underlying physics
Conducting several measurements
Outlook: measure a signal from the Tower-jazz chip
analyse data of three contiguous pixels
May 5, 2017
Alina Arranhado

18. CONCLUSIONS It was a very positive experience!
Measuring beam spot shape (width)
Calibration of Voltron
Meeting very interesting people
Understanding underlying physics
Conducting several measurements
Outlook: measure a signal from the Tower-jazz chip
analyse data of three contiguous pixels
It was a very positive experience!
May 5, 2017
Alina Arranhado

19. THANK YOU!
May 5, 2017
Alina Arranhado