Status overview of the radiation hardness assurance studies for FCC Rubén García Alía, Markus Brugger, Giulio Borghello, Mar Capeans, Francesco Cerutti, Salvatore Danzeca, Federico Faccio, Georgi Gorine, Simone Gilardoni, Angelo Infantino, Michael Moll, Federico Ravotti, Benjamin Todd, Slawosz Uznanski R2E Project, task 11 of FCC Special Technologies WP

FCC week 2017 - Status of RHA studies Outline Radiation Hardness Assurance (RHA): approach and building blocks Challenges for qualification in radiation facilities Challenges at system level Challenges at component/technology level Conclusions and Outlook May 31, 2017 FCC week 2017 - Status of RHA studies

FCC week 2017 - Status of RHA studies Outline Radiation Hardness Assurance (RHA): approach and building blocks Challenges for qualification in radiation facilities Challenges at system level Challenges at component/technology level Conclusions and Outlook May 31, 2017 FCC week 2017 - Status of RHA studies

FCC week 2017 - Status of RHA studies The RHA challenge System level testing, common developments, monitoring and calculation Optimal compromise between rad-tol design and qualification costs and impact on operation Components not qualified for radiation No radiation level criterion (monitoring, calculation) Low system reliability/availability due to radiation High costs associated to need of mitigating radiation effects once system is in operation Worst-case condition testing at component level Large margins Rad-hard components Very large system reliability at very high cost May 31, 2017 FCC week 2017 - Status of RHA studies

Key building-blocks Radiation Test Facilities Qualification Approach Radiation Monitoring and Calculation Rad-hard component design (experiments) Rad-tol system development based on COTS (accelerator) Radiation Hardness Assurance Qualification Approach Radiation Test Facilities May 31, 2017 FCC week 2017 - Status of RHA studies

Radiation environment In the detector (30 ab-1): First layer of inner barrel: 6×1017 neq/cm2, 400 MGy Forward calorimeter: 5×1018 neq/cm2, 10 GGy Expected levels for HL-LHC: 1016 neq/cm2, 10 MGy → already extremely challenging, baseline is to change pixels at half-life (sensor + electronics); no solution available for FCC first layers today In the accelerator arc section (annual): Below the magnets: ~1011 HEH/cm2/yr, ~100 Gy/yr In the optimized alcoves: below ~108 HEH/cm2/yr Future work: radiation levels in LSS tunnel, alcoves near interaction region, dispersion suppressor, collimation… I. Besana, FCC week 2017 ~108 HEH/cm2/yr ~1011 HEH/cm2/yr A. Infantino, FCC week 2017 May 31, 2017 FCC week 2017 - Status of RHA studies

FCC availability requirements FCC baseline: luminosity production targets can be reached with LHC like overall performance Target availability budget similar to LHC values For today’s machine, systems exposed to radiation and involving complex electronics, we can typically accept a 10% of the total failure budget to radiation Example: FCC power converter budget would be 2.5 radiation failures/100 days (just as reference) Additional constraints linked to short stable beam time: Importance of injector availability Importance of minimizing downtime for optimal turnaround With input from A. Apollonio (TE-MPE) and A. Niemi (BE-ICS) May 31, 2017 FCC week 2017 - Status of RHA studies

FCC week 2017 - Status of RHA studies Outline Radiation Hardness Assurance (RHA): approach and building blocks Challenges for qualification in radiation facilities Challenges at system level Challenges at component/technology level Conclusions and Outlook CERN facility database (http://irradiation-facilities.web.cern.ch/) and analysis on possible limitations for FCC (G. Gorine, FCC week 2017 poster) May 31, 2017 FCC week 2017 - Status of RHA studies

IRRAD for displacement damage Shuttle System IRRAD Proton Facility in 2016: 416 objects at RT, -25oC and 1.9K >400 dosimetry measurements 28 user teams with 52 experiments >1017 p/cm2 delivered  >30 MGy/year (HL-LHC ready; DD qualification for FCC remains a challenge) Beam momentum: 24 GeV/c Beam spot: 12×12 mm2 (FWHM) Proton flux: ~1016 p/cm2 in 5 days Several optics possible variants. Cold Boxes IRRAD Zone 1 May 31, 2017 FCC week 2017 - Status of RHA studies

X-ray machines for total ionizing dose (TID) Today, several X-ray generators are used in parallel and in their full capacity to provide 10 MGy in 5-7 days Detector systems requiring tests for multi-100MGy levels will certainly need many more sources than those presently available today May 31, 2017 FCC week 2017 - Status of RHA studies

FCC week 2017 - Status of RHA studies CHARM for SEEs A unique facility for qualifying component batches and system in a high-energy accelerator environment Lifetime (20+ yr) radiation levels for electronic equipment to be installed in the LHC and its injectors can be reached in ~1 week May 31, 2017 FCC week 2017 - Status of RHA studies

CHARM for HL-LHC SEE qualification 600A and 4-6-8 kA power converters located in RRs of P1, 5 and 7 128 and 66 units respectively Average expected annual fluence for HL-LHC: 1.4 and 2.7×109 HEH/cm2 respectively HL-LHC R2E failure budget for power converters of one dump per year Target upper limit cross sections of ~3×10-12 cm2/unit, close to CHARM limit A. Tsinganis, 6th annual HL-LHC Collaboration Meeting, Paris, November 2016 May 31, 2017 FCC week 2017 - Status of RHA studies

CHARM for FCC SEE qualification Let’s consider a distributed system with 4000 units Located in the arc alcoves, with annual HEH fluence values of 108 HEH/cm2 Located in the arc tunnel below the magnets, with annual HEH fluence values of 1011 HEH/cm2 In order to comply with an R2E failure budget of 5 dumps per year, cross sections of 10-11 cm2/unit to 10-14 cm2/unit would need to respectively be qualified Conclusion: for equipment located in the tunnel (or shielded areas with similar radiation levels, e.g. alcoves near interaction points or collimation) the FCC SEE requirements cannot be qualified with today’s CHARM facility performance ~108 HEH/cm2/yr A. Infantino, FCC week 2017 ~1011 HEH/cm2/yr May 31, 2017 FCC week 2017 - Status of RHA studies

FCC week 2017 - Status of RHA studies Outline Radiation Hardness Assurance (RHA): approach and building blocks Challenges for qualification in radiation facilities Challenges at system level Challenges at component/technology level Conclusions and Outlook May 31, 2017 FCC week 2017 - Status of RHA studies

FCC week 2017 - Status of RHA studies System level testing Efficiently combining top-down (from system to sub-system/component) and bottom-up (discrete testing of critical components) approaches Importance of intelligent design of experiment in order to enhance failure observability (e.g. self-diagnose systems) Importance of defining failure modes and associated criticality Importance of common component qualification and sub-system development (e.g. versatile communication link) FGClite system for LHC power converter controls (S. Uznanski, TE-EPC) May 31, 2017 FCC week 2017 - Status of RHA studies

Redundancies for enhanced radiation tolerance From a radiation tolerance perspective: Soft Error failure state (e.g. Single Event Functional Interrupt) can typically be removed with remote power-cycle/restart Hard Errors (destructive) would need actual hardware replacement of component/board Possible redundancy: failure detection, switch to redundant sub-system without impacting operation, minimize repair time (reset or online hot-swap, without interrupting operation) → comes at a very high cost, thus important to balance development investment and system availability A well implemented redundancy can allow to retrieve operational SEE cross sections much lower than those experimentally qualified May 31, 2017 FCC week 2017 - Status of RHA studies

Links to other applications High radiation levels, low number of systems, extremely high criticality Space missions High radiation levels, intermediate number of systems, high criticality Low-cost space missions Accelerators Low radiation levels, very high number of systems, intermediate criticality Ground-level May 31, 2017 FCC week 2017 - Status of RHA studies

The RADSAGA innovative training network Marie Curie network coordinated by CERN (http://radsaga.web.cern.ch/) Main objective: to deliver a handbook on guidelines for system level radiation testing for space, avionic, ground-level and accelerator applications May 31, 2017 FCC week 2017 - Status of RHA studies

FCC week 2017 - Status of RHA studies Outline Radiation Hardness Assurance (RHA) challenges and building blocks Accelerated testing in mixed-field facilities: role in qualification procedure and limitations Challenges at system level Challenges at component/technology level Conclusions and Outlook May 31, 2017 FCC week 2017 - Status of RHA studies

Technology scaling challenges CMOS transistors in sub-250nm nodes have very thin gate oxides, almost insensitive to TID effects However thick lateral (STI) and spacer oxides are still sensitive to TID, degrading the performance at large values First measurements of 28nm transistors show larger TID tolerance than 65nm, studied for HL-LHC upgrades → still a huge challenge for FCC levels Several 28nm and 40nm CMOS processes will be studied to extract possible trends and select best candidates for ASIC design 10 MGy 10 MGy F. Faccio, G. Borghello May 31, 2017 FCC week 2017 - Status of RHA studies

Technology scaling challenges (II) Example: thermal neutron SEU sensitivity as a function of transistor technological As of 0.25 μm: no 10B used in passivation R2E tests on state-of-the-art SRAM based FPGA show strong thermal neutron sensitivity, expected to dominate SEU rate in accelerator shielded environment Possible origin: 10B as dopant or plug contamination Similar challenge: direct ionization from singly charged particle, Further example: SiC (solid-state switches for kicker applications) sensitivity to SEB, first tests at CHARM carried out in 2016 Infantino, ICRS13 (2016) Yamazaki, JVSTB (2015) R2E measurements May 31, 2017 FCC week 2017 - Status of RHA studies

FCC week 2017 - Status of RHA studies Outline Radiation Hardness Assurance (RHA) challenges and building blocks Accelerated testing in mixed-field facilities: role in qualification procedure and limitations Challenges at system level Challenges at component/technology level Conclusions and Outlook May 31, 2017 FCC week 2017 - Status of RHA studies

Conclusions and Outlook Ingredients for FCC RHA approach: Expected radiation levels Availability/lifetime targets FCC RHA considerations at system level Development and qualification of common building blocks (e.g. FPGA processing units, communication links) is essential Self-diagnose, redundancies and remote interventions can significantly reduce failure probability and impact on downtime FCC RHA considerations at technology level Micro-electronic technology evolves extremely rapidly, thus requiring a continuous study of related effects Possible limitations related to TID degradation of deep sub-micron transistor technologies → radiation levels at least an order of magnitude larger than those expected for HL-LHC, therefore R&D in radiation hardness of sensor and front-end electronics is essential Already beyond today’s performance and qualification limits (but margin from improvement) May 31, 2017 FCC week 2017 - Status of RHA studies

Thanks for your attention! May 31, 2017 FCC week 2017 - Status of RHA studies