1. Ingrid-Maria Gregor (University Wuppertal) for the ATLAS collaboration June 6th, 2000 Optical Links for the ATLAS SCT and Pixel Detector International Workshop on Semiconductor Pixel Detectors for Particles and X-Rays Genova, Italy June 2000

2. Pixel2000 Genova, Italy Ingrid-Maria Gregor University of Wuppertal 2 Overview äATLAS Inner Detector äOptical Link Architecture äSystem Tests äConclusion

3. Pixel2000 Genova, Italy Ingrid-Maria Gregor University of Wuppertal 3 ATLAS Inner Detector

4. Pixel2000 Genova, Italy Ingrid-Maria Gregor University of Wuppertal 4 Data Transfer äControl and clock information must be transferred from acquisition system to the silicon detectors äHit data must be transferred from the modules to a remote acquisition system äuse of copper links unfeasible âlarge amount of dead material which would be introduced âproblems from cross-talk and ground loops äit is proposed to use custom optical links to transfer data to and from the detector modules (SCT and Pixel Detector)

5. Pixel2000 Genova, Italy Ingrid-Maria Gregor University of Wuppertal 5 Special Requirements (1) äradiation hardness âionizing radiation : 100kGy (SCT) to 550kGy (Pixel detector) â1 billion lung x-rays âneutron radiation : ãSi-devices: 1*10 15 n(1MeV)/cm 2 ãGaAs-devices: up to 6.4*10 15 n(1MeV)/cm 2 âexpected over the 10 year lifetime of ATLAS (1 st layer)

6. Pixel2000 Genova, Italy Ingrid-Maria Gregor University of Wuppertal 6 Special Requirements (2) änon-magnetic to avoid perturbing the inner detector magnetic field älow mass âadditional interactions in non-instrumented regions of the detector would compromise the quality of momentum measurements âparticle conversion äreasonably low cost

7. Pixel2000 Genova, Italy Ingrid-Maria Gregor University of Wuppertal 7 Read-Out Link Architecture Vertical Cavity Surface Emitting Laser

8. Pixel2000 Genova, Italy Ingrid-Maria Gregor University of Wuppertal 8 Timing Triggering and Control (TTC link) äVCSEL Driver BiPhase Mark Encoder ädriver chip for VCSEL on acquisition side (12 way) ä40MHz-Clock and Commands on one link

9. Pixel2000 Genova, Italy Ingrid-Maria Gregor University of Wuppertal 9 TTC Link äDigital Optical Receiver IC ädecodes the signals received by the PIN ärecovers commands and 40MHz-clock äLVDS output ä2 versions: bipolar (SCT) and CMOS (Pixel) äSCT redundancy system: TTC data can be taken from redundancy link from a neighbouring data

10. Pixel2000 Genova, Italy Ingrid-Maria Gregor University of Wuppertal 10 Data Link äVCSEL Driver Chip äLVDS input ä40Mbit/s (SCT), 80Mbit/s (Pixel 1st and 2nd layer) or 160Mbit/s (B-layer) äNRZ (20MHz = 40Mbit/s) ä2 versions: bipolar (SCT) and CMOS (Pixel) äSCT: in the event of failure, the data can be rerouted through the second link äPixel: one link for outer layers, two for B- layer (160MBit/sec)

11. Pixel2000 Genova, Italy Ingrid-Maria Gregor University of Wuppertal 11 Opto-Package Specs äCustom package made of material with low Z, non- magnetic, with 2 VCSELs and 1 PIN äFibres attached without standard connector änot larger than 5.5 mm x 5.5 mm x 1.6 mm äpackage and including devices have to stand radiation levels äoperation temperature during testing: -25 o C to 40 o C äoperation temperature during ATLAS: -25 o C to 15 o C äthree different designs under survey

12. Pixel2000 Genova, Italy Ingrid-Maria Gregor University of Wuppertal 12 Taiwan Opto-Package

13. Pixel2000 Genova, Italy Ingrid-Maria Gregor University of Wuppertal 13 Taiwan Opto-Package 5.5 mm

14. Pixel2000 Genova, Italy Ingrid-Maria Gregor University of Wuppertal 14 Taiwan Opto-Package

15. Pixel2000 Genova, Italy Ingrid-Maria Gregor University of Wuppertal 15 Opto-Elbow (Pixel) Module Pigtail Opto Elbow Bending Zone Solder Connection Single Side Glue Attachment & Wire Bonding DORICVDC Opto-Package

16. Pixel2000 Genova, Italy Ingrid-Maria Gregor University of Wuppertal 16 Opto Package Support (SCT) VDC (VCSEL Driver Chip) DORIC (Receiver Chip) VCSEL/PIN Package ZIF Connector Kapton Cable Opto Hybrid Module Connector

17. Pixel2000 Genova, Italy Ingrid-Maria Gregor University of Wuppertal 17 System Tests äCharacteristics of opto-link for this system under test: âRadiation and Annealing studies âLifetime studies âBit Error Rate âSingle Event Upsets

18. Pixel2000 Genova, Italy Ingrid-Maria Gregor University of Wuppertal 18 Annealing Studies of VCSEL 00:0024:0048:0072:0096:00 0,0 0,2 0,4 0,6 0,8 1,0 Average Relative Light Output (RLO) Annealing time [h] RLO of VCSEL (group A) annealed at 10mA RLO of VCSEL (group A) annealed at 20mA RLO of VCSEL (group B) annealed at 10mA RLO of VCSEL (group B) annealed at 20mA Light Output before Irradiation Light Output after Irradiation RLO = Radiation levels:

19. Pixel2000 Genova, Italy Ingrid-Maria Gregor University of Wuppertal 19 VCSEL tests äVCSELs were not powered during irradiation äradiation induced damages can be annealed up to 90% over a period of days/weeks äresults suggest brief 20 mA current annealing sessions äfollowing aging tests showed an expected lifetime of a few hundred years (irradiated) äfurther irradiation and lifetime tests are under way (up to Pixel level of 6.4*10 15 n(1MeV)/cm2)

20. Pixel2000 Genova, Italy Ingrid-Maria Gregor University of Wuppertal 20 Bit Error Rate (BER) äBER: good parameter to evaluate the performance of the optolink äGood results with SCT link äPixel test under way

21. Pixel2000 Genova, Italy Ingrid-Maria Gregor University of Wuppertal 21 Single Event Upsets äSingle Event Upsets caused by a very high energy deposition in a small volume of electronics chips ämost sensitive region: reverse-biased p/n junction where high electric field is very effective in collecting the charge by drift äPIN = reverse biased p/n junction  100m x 50m x 50m ! äFirst SEU appearance : NPL neutron beam ätest with pions at PSI

22. Pixel2000 Genova, Italy Ingrid-Maria Gregor University of Wuppertal 22 SEU at PSI  Sensitive power around 100W  for P>350W, BER <10 -10 s -1 ädiscrepancy between counter and Al foil ärepeat next week

23. Pixel2000 Genova, Italy Ingrid-Maria Gregor University of Wuppertal 23 Conclusion ädata transfer using optical links äcustom packaging developments for the 40 Mb/s optical link show good physical results ädesign of complete Pixel opto-link under way äradiation induced damages can be annealed up to 90% over a period of days äresults suggest brief 20 mA current annealing sessions äSEU problems can be fixed by sending more light

24. Pixel2000 Genova, Italy Ingrid-Maria Gregor University of Wuppertal 24 Conclusion ähttp://www.atlas.uni-wuppertal.de/ Optolink/Pix_Optolink.html