Studies of silicon strip sensors for the ATLAS ITK project. Miguel Arratia Cavendish Laboratory, University of Cambridge

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Patience Stevenson
5 years ago
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1 Studies of silicon strip sensors for the ATLAS ITK project Miguel Arratia Cavendish Laboratory, University of Cambridge 1

2 ITK project and radiation damage Unprecedented large fluences expected for the High Luminosity era of the LHC, with aim to collect 3000 /fb ITK-strip layers need to endure 10e15 neq 2

3 Outline Quality assurance of full-size ATLAS12 prototype sensors Radiation damage studies using irradiated mini-sensors 3

4 Electrical characterization of large-area ATLAS12 prototypt sensors. 4

5 Semi-automatic probe station 5

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9 IV curves 9

10 CV curves 10

11 Visual inspection with CMM 11

12 Sensor bow with CMM 11x11 grid with mm spacing Flat plane fitted and subtracted to obtain net bow 12

13 Full strip tests Test of strip integrity, measurement of bias resistance and coupling capacitance (both with LCR measurement) 13

14 Faulty strips Searching for systematic pattern, but statistics of defects is very small. 14

15 Coupling capacitance, Bias resistance 15

16 Coupling capacitance, Bias resistance 16

17 Summary 17

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19 Outline Quality assurance of full-size ATLAS12 prototype sensors Radiation damage studies using irradiated mini-sensors 19

20 ATLAS miniature prototypes, aka baby 1x1 cm2 from same wafer of main sensor Main purpose is for R&D (variation of some features) and irradiation with beams or nuclear reactors. Need to study how charge collection degradates with radiation damage 20

21 Ingredients for charge collection efficiency measurement Plastic scintillator coupled with photomultiplier (trigger) Radioactive source (90Sr) Readout electronics 21

22 DAQ system Comercial FPGA based DAQ system developed by Liverpool, Barcelona and Valencia Uses the LHCb Beetle chip, readout at 40 MHz. Analogue readout, for R&D purposes 22

23 Readout daughterboad 23

24 Wirebonding I have learnt how to use this automatic wirebonder machine (time of technicians in our groups is too precious to be bothering them all the time for this) 24

25 Wirebond evaporation due to microdischarges Learnt the hardway to give ample clearance from HV to ground wirebonds! 25

26 Mounting setup 26

27 Setting up PMT 27

28 Dark box, lead shielding 28

29 Room Temperature setup 29

30 Working room temperature setup, ready for Run-1 30

31 Pedestals and noise levels 31

32 Time distribution 32

33 Clustering Very simple clustering algorithm. Start with hit with highest S/N, then add strips to cluster until S/N is below 1.8 sigma. 33

34 Landau distribution Charge of clusters follows a Landau distribution, convolved with Gaussian resolution. 34

35 Most probable value vs charge Textbook like example of MPV vs bias voltage. This sensor (ATLAS07) reaches full depletion at about 200 V 35

Upgrade to cold setup Why do we need to measure at cold temperature? Goal is to study radiation damage on silicon sensors. Defects created by irradiation can diffuse. Effect calling annealing.

36 Upgrade to cold setup Why do we need to measure at cold temperature? Goal is to study radiation damage on silicon sensors. Defects created by irradiation can diffuse. Effect calling annealing. It is highly dependent on temperature. Freeze sensor tu suppress annealing, to study the initial damage. Example: Leakage current increases with irradiation fluence but sensor cures if annealed 36

37 Moving setup to the fridge 37

Daughter board does include temperature sensor. Problem: but is near frontend chip, and there is a temperature gradient to sensor. Fridge includes its own temperature sensor.

38 Daughter board does include temperature sensor. Problem: but is near frontend chip, and there is a temperature gradient to sensor. Fridge includes its own temperature sensor. Problem: not near enough sensor/frontend chip. Placed a temperature sensor very near Si-sensor, Arduino controlled. Temperature also checked IR camara (during data taking). 38

39 IR camera placed inside the fridge. It was stored in dry storage before to avoid condensation. No large variations in temperature registered during operation. But still did not last long before pixels started to fade away 39

40 Some simple CAD I even did design a plug, seal, for flow of nitrogen to My wife (mechanical engineer) helped me with software :D 40

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43 CCE vs fluence, proton irradiation 43

44 CCE vs fluence, protons and neutrons 44

45 Annealing studies Radiation-induced damage anneals with temperature. Important to quantify the good and bad annealing time scales. I use this enviromental chamber to cook the sensors at 60C for controlled periods of time, in dry atmosphere (N2 flushing) 45

46 LabVIEW scripts to automate CCE measurement I learnt LabVIEW to automate process, only way to get voltage scan from 100V to 1kV with 1.5 hours per point, different annealing times and different sensors 46

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48 Setup for IV measurements 48

49 Setup for CV measurement 49

50 Setup for interstrip resistance 50

51 Examples were I learnt the hard way 51

52 My setup over time 52

Radiation hardness and precision timing study of Silicon Detectors for the CMS High Granularity Calorimeter (HGC)

Radiation hardness and precision timing study of Silicon Detectors for the CMS High Granularity Calorimeter (HGC) Esteban Currás1,2, Marcos Fernández2, Christian Gallrapp1, Marcello Mannelli1, Michael