1. www.hib.no Ketil Røed - LECC2005 Heidelberg Irradiation tests of the ALICE TPC Front-End Electronics chain Ketil Røed Faculty of Engineering, Bergen University College

2. www.hib.no Ketil Røed - LECC2005 Heidelberg ALICE and the TPC Front-End Electronics TPC (Time Projection Chamber) Main tracking detector High particle multiplicities Front-End Electronics (RCU) High data rates Complex readout electronics Outline  Radiation concerns for TPC FEE  Irradiation tests  Results and outlook

3. www.hib.no Ketil Røed - LECC2005 Heidelberg 36 TPC Sectors, served by 6 readout subsystems, Readout Control Unit (RCU) in total 216 RCUs and 4356 Front-End Cards Ethernet ( 1 MB/s ) Detector Data Link ( 200 MB / s ) COUNTING ROOM ALTRO bus ( 200 MB / s ) ON DETECTOR FEC 128 ch 1 13 2 14 12 25 FEC 128 ch FEC 128 ch FEC 128 ch FEC 128 ch FEC 128 ch DETECTOR TTC optical Link (Clock, L1 and L2 ) RCU DCS board SIU interface Trigger interface ALTRO Bus Interface Monitoring and Safety Module Data assembler Branch A Branch B Data Acquisition Detector Control System Trigger and Clock System Local Slow- Control (I 2 C-serial link) TPC Front-End Electronics

4. www.hib.no Ketil Røed - LECC2005 Heidelberg RCU motherboard :2 FPGAs (SRAM/FLASH) DCS: 1 FPGA (SRAM) SIU:1 FPGA (Flash) Readout Control Unit (RCU)

5. www.hib.no Ketil Røed - LECC2005 Heidelberg - Close to interaction point - Exposed to radiation Front End Electronics 1. Simulations of the radiation environment 2. Irradiation tests of electronics FEE & radiation concern

6. www.hib.no Ketil Røed - LECC2005 Heidelberg - Main particles of concern are hadrons of energy above 10-20 MeV - Peak at 100-200 MeV Morsch Sandoval Tsiledakis FEE & radiation levels

7. www.hib.no Ketil Røed - LECC2005 Heidelberg Dose calculations  Electronic stopping power (direct ionization) SEU  Stopping power of recoil ion from nuclear reactions Total dose : 5.7 Gy or ~0.6kRad (10 ALICE years TPC electronics) (Morsch et. al.) Hadron flux : ~ 800 hadrons/cm^2-s (worst case) Energy loss rate (MeV-cm^2/g) Energy (MeV) Electron. Stp. Pwr. Nuclear Stp. Pwr. Direct ionization & Nuclear reactions

8. www.hib.no Ketil Røed - LECC2005 Heidelberg Single Event Effects (SEE) SEE : Single event effects are radiation induced errors due to a single charged particle depositing energy through ionisation of the material. -Single Event Latch-up (SEL) -Single Event Upset (SEU) -Single Event Functional Interrupt (SEFI) Cumulative effects - Total ionising dose (TID) - Displacement damage Radiation effects

9. www.hib.no Ketil Røed - LECC2005 Heidelberg Nuclear interaction with the silicon nuclei - Neutrons and high energetic hadrons - Heavy recoil (E < 6-10 MeV) - Sensitive area and critical energy Si p High energy protons will not deposit enough ionization energy to cause and SEU Nuclear reactions & SEU

10. www.hib.no Ketil Røed - LECC2005 Heidelberg FPGA: Field Programmable Gate Array Array of programmable logic blocks Logic gates, LUTs, flip-flops etc SRAM configuration memory Controls behaviour of the logic blocks Sensitive to ionizing particles Configuration memory may change content: 1  0 / 0  1 Programmable devices

11. www.hib.no Ketil Røed - LECC2005 Heidelberg Single components: Test method: - Xilinx Virtex-II Pro 7 (RCU) - Altera APEX20K400E (RCU old prototype) SEU/SEFI for SRAM based FPGAs and memory - Actel proAsic APA075 (RCU) Dose for flash based FPGAs and memory DCS Emb. Computer Full FEE readout chain DOSE & SEFI System level: Irradiation tests of the TPC FEE Focus is put on the RCU motherboard and DCS board:

12. www.hib.no Ketil Røed - LECC2005 Heidelberg - Altera APEX20K400E - Xilinx Virtex Pro 7 - Actel ProASIC APA075 Single component tests Test design: Shiftregister filling the device

13. www.hib.no Ketil Røed - LECC2005 Heidelberg DCS embedded computer Single board computer used in several detectors in ALICE Combines LINUX operating system with a Programmable Logic Device (PLD) System level tests - DCS

14. www.hib.no Ketil Røed - LECC2005 Heidelberg Integration test of full FEE readout chain FECs DCS board RCU motherboard SIU card System level test – Full integration Run as close to normal data taking conditions as possible Prototype versions of firmware & software

15. www.hib.no Ketil Røed - LECC2005 Heidelberg Local Trigger Unit TTCvi TTCex Single board computer Positioned in a low radiation field Local Trigger Crate (LTC) System level test – Full integration

16. www.hib.no Ketil Røed - LECC2005 Heidelberg Proton irradiation - Single components - Energy: ~29 MeV - Flux 10^6-10^7 [p/cm^2/s] - Beam spot: 2x2 cm Oslo Cyclotron, Department of Physics, University of Oslo (Jon Wikne and Evind A. Olsen) Irradiation tests at OCL

17. www.hib.no Ketil Røed - LECC2005 Heidelberg Proton irradiation - Single components (& DCS system) - Energy: 38 & 180 MeV - Flux 10^6-10^7 [p/cm^2/s] Neutron irradiation - Secondary customers - Energy: 50, 95, 180 MeV - Flux: 10^3 – 10^4 [n/cm^2/s] - Fluence: 1.5*10^9 [n/cm^2] Irradiation tests at TSL

18. www.hib.no Ketil Røed - LECC2005 Heidelberg (@ 180 MeV) High energetic hadron flux: 100-400 hadrons/cm^2-s Expected number of SEFI for the whole TPC detector: 3-4 per run SEU measured for VP7  CS 10-20 higher than for SEFIs Results – Altera APEX & Xilinx VP7

19. www.hib.no Ketil Røed - LECC2005 Heidelberg Expected dose in 10 Alice years 0.6 kRad Actel readback and verification (R/V) software Readback and verification increased the radiation sensitivity R/V procedure not intended to be used during operation No SEUs detected! Results – Actel proASIC APA075

20. www.hib.no Ketil Røed - LECC2005 Heidelberg Stand alone system test at 180 MeV nominal proton beam Typical failure:  Loss of Ethernet connection (expected)  Large part of the firmware design Stopped irradiation after total dose of 1.5 kRad  Equivalent to ~2 ALICE lifetimes  DCS system fully functional at end of irradiation  Ran stable for 3 hours after irradiation Mean time until first error is 316 sec  Cross-section = 2.1 * 10^9 cm^2  MTBF for 216 DCS boards: 0.8 – 1.6 hours  DCS board not in data path  tolerate some downtime (acceptable) Results – DCS system level test

21. www.hib.no Ketil Røed - LECC2005 Heidelberg DeviceExpected errorsTest results DCS*3.15 (2xDCS) RCU FPGA*43 Crate**-3 *(fluence: 1.5 * 10^9 n/cm^2, 25 hours @ 95 MeV) **(fluence 1.7 * 10^8 n/cm^2, 19 hours @ 180 MeV) - DCS embedded computer  2 DCS boards  All errors related to the loss of Ethernet connection - RCU FPGA  3 errors cleaned by reconfiguration of device - Trigger crate  Neutron fluence equivalent to an ALICE lifetime  3 SEUs (monitor program of single board computer)  no indication of errors in the trigger boards (TTCvi, TTCex, LTU) neutrons @ TSL Results – TSL integration test

22. www.hib.no Ketil Røed - LECC2005 Heidelberg Actel FPGA (Flash):  Dose results satisfying  Survived ~10 ALICE lifetimes SRAM based FPGAs:  Error rate at the limit of what can be tolerated (RCU board)  Radiation tolerent schemes - Detect SEUs instantaneously - Real-time read back of configuration memory - Active partial reconfiguration (supported by Xilinx) - Error detection and correction measures  DCS board not in datapath  acceptable results Conclusion of irradiation tests

23. www.hib.no Ketil Røed - LECC2005 Heidelberg - DCS downloads firmware to FLASH - Configure Xilinx - Read back fram by from and compare with flash - ”Scrubb” on demand or continuously Configuration/”scrubbing” of VP7

24. www.hib.no Ketil Røed - LECC2005 Heidelberg Scrubbing started after ~200 s: Errors are corrected Continuously Full “scrubb” ~sec Increased time to first SEFI 601802403600seconds120 32 Bit Lines, RED = Errors G. Tröger, KIP Flux: 2 * 10^4 lower Scrubbing: 1 * 10^2 faster Normal operation  Plain Shift Register (flux ~1.5*10 7 p/cm 2 -s) Preliminary test results with “scrubbing”

25. www.hib.no Ketil Røed - LECC2005 Heidelberg Continue irradiation campaign to improve methods and statistics  Single components  System level Investigate and implement further radiation protection measures  Firmware design issues (EDAC, TMR etc) Increase knowledge on  Radiation effects in complex devices Active partial reconfiguration & radiation protection measures  Reduce the effects of SEUs to a negligible level Outlook

26. www.hib.no Ketil Røed - LECC2005 Heidelberg 15 J. Alme, D. Larsen, M. Richter, D. Röhrich, K. Ullaland Department of Physics and Technology, University of Bergen, Norway H. Helstrup, K. Røed Faculty of Engineering, Bergen University College, Norway V. Lindenstruth, G. Tröger Kirchhoff Institute of Physics, University of Heidelberg, Germany R. Campagnolo, C. Gonzalez Gutierrez, L. Musa CERN, European Organization for Nuclear Research, Geneva, Switzerland E. Olsen, B. Skaali, J. Wikne Department of Physics, University of Oslo A. Prokofiev The Svedberg Laboratory, Uppsala University Acknowledgments

27. www.hib.no Ketil Røed - LECC2005 Heidelberg Thanks for your attention !