The COTS use in harsh Radiation environment of the CERN accelerators complex

Outline

• Introduction to R2E problematic in accelerators
• Accelerator radiation environment
• Radiation Hardness Assurance approach
• RADSAGA and RADNEXT
• Main takeaways

COTS-based critical equipment near the accelerator

• Main reason requiring operation near accelerator:
  • Cable distance to accelerator elements (magnets, vacuum, cryogenics, RF, beam instrumentation…)
  • Lack of radiation-safe areas around accelerator (underground machine)
• Main drivers for use of COTS:
  • Cost
  • Performance
  • Availability and timeline
• A typical example of system-level SEE requirement: one R2E failure per critical system per year

R2E impact on accelerator performance

• Critical LHC systems are interlocked: their main function is to protect the machine integrity, therefore in case of the fault/spurious signal, the beam will be dumped (i.e. extracted from LHC in a controlled manner)
• An R2E event (soft/hard) can result in the loss of beam (turn- around time of 2-3 hours) and/or the need of access (further 3-4h of downtime)
• 0.1 dumps/Fb-1 involves an upper limit of 25 R2E dumps/year or roughly one per week of operation
• Given the number of critical systems exposed to radiation, this translates into an R2E failure budget of a few (2-3) per system and year – we consider one per year as a design requirement.
• If we consider the (realistic) case of 1000 units exposed to 109 HEH/cm2 /year, one failure per system and year involves:
  • A unit failure rate of one in 1000 years* (MTBF of 2.8∙106 hours, or 350 FITs)
  • A system-level SEE cross-section upper limit of 10-12 cm2 /unit

Detector environment and electronics

• For the HL-LHC (High-Luminosity LHC) detector electronics, to operate between 2025 and 2035, radiation levels of up to 10 MGy (1 Grad) and 1016 neq/cm2 are expected, thus requiring the use of rad-hard by design electronics
  • Example of rad-hard design for high-energy accelerator detector electronics: Giga-Bit Transceiver (GBT)
  • Started in 2007 as a rad-hard bi-directional optical link for the LHC detector upgrade program
  • Data transmission between front-end detector, exposed to radiation, and back-end, in radiation safe area
  • Radiation constraints: SEE-free, 1 MGy TID (and no DD limit as it can be neglected for CMOS)
  • Qualification: X-rays for TID, heavy ions for SEE
  • Timeline and cost for development & qualification are beyond the scope of systems for the accelerator sector

Accelerator environment

• The radiation levels in the accelerator span over many orders of magnitude (e.g. GGy irradiation of beam screens for material damage) but typically COTS-based systems are foreseen to operate in areas with levels below 200 Gy for ~20 years operation
  • The 200 Gy limit is mainly motivated by (i) the relatively large amount of areas near the accelerator fulfilling this condition, (ii) the fact that selected COTS can be used up to such levels
• Importance of monitoring and simulating radiation levels in order to provide specifications for equipment groups designing and qualifying radiation tolerant systems

Accelerator environment – areas near Interaction Points

• Radiation levels near interaction points dominated by collision debris
• Expected TID and DD levels in the accelerator tunnel for system lifetime (~10-20 years) can reach 100 kGy and 1015 neq/cm2, therefore excluding the use of COTS
• Shielded alcoves (~40-200 cm of concrete/iron shielding) host electronic systems in this part of the accelerator, with HEHeq levels of 107 -109 HEH/cm2 /year, therefore posing a threat in terms of SEEs

RADSAGA: an on-going Marie Curie training network of 15 student projects across Europe working on radiation effects for space, avionic, ground level and accelerator applications

http://radsaga.web.cern.ch/

RADNEXT: an EU proposal in preparation for  enhanced service and accessibility to irradiation beam time for research applications in academia and industry

Interested partners and users can contact radnext-proposal-coordination@cern.ch

Presentation takeaways

• The CERN accelerator sector makes extensive use of COTS-based custom systems, operating successfully in radiation environment and with challenging availability and lifetime constraints
• High-reliability operation of COTS-based systems in radiation environments is possible in a cost-efficient manner, but relies heavily on:
  • Consideration of radiation environment and specification of required tolerance at a very early stage of system definition (otherwise, a strong price is paid in terms of machine performance and mitigation measures)
  • Centralized support for part selection, architecture definition and component & system level radiation testing

Recent R2E publications

• M. Brucoli et al., “Investigation on Passive and Autonomous Mode Operation of Floating Gate Dosimeters,” in IEEE Transactions on Nuclear Science, vol. 66, no. 7, pp. 1620-1627, July 2019.
• M. Brucoli et al., “Investigation on Passive and Autonomous Mode Operation of Floating Gate Dosimeters,” in IEEE Transactions on Nuclear Science, vol. 66, no. 7, pp. 1620-1627, July 2019.
•  R. Ferraro et al., “Study of the Impact of the LHC Radiation Environments on the Synergistic Displacement Damage and Ionizing Dose Effect on Electronic Components,” in IEEE Transactions on Nuclear Science, vol.66, no. 7, pp. 1548-1556, July 2019.
• M. Cecchetto et al., “SEE Flux and Spectral Hardness Calibration of Neutron Spallation and Mixed-Field Facilities,” in IEEE Transactions on Nuclear Science, vol. 66, no. 7, pp. 1532-1540, July 2019.
• P. Fernández-Martínez et al., “SEE Tests With Ultra Energetic Xe Ion Beam in the CHARM Facility at CERN,” in IEEE Transactions on Nuclear Science, vol. 66, no. 7, pp. 1523-1531, July 2019.
• R. G. Alía et al., “Ultraenergetic Heavy-Ion Beams in the CERN Accelerator Complex for Radiation Effects Testing,” in IEEE Transactions on Nuclear Science, vol. 66, no. 1, pp. 458-465, Jan. 2019.
• C. Martinella et al., “Current Transport Mechanism for Heavy-Ion Degraded SiC MOSFETs,” in IEEE Transactions on Nuclear Science, vol. 66, no. 7, pp. 1702-1709, July 2019.

Further References

• “FLUKA Simulations for SEE Studies of Critical LHC Underground Areas”, K. Roed et al, IEEE TNS, 2011 • “LHC RadMon SRAM Detectors Used at Different Voltages to Determine the Thermal Neutron to High Energy Hadron Fluence Ratio”, D. Kramer et al, IEEE TNS 2011
• “Method for Measuring Mixed Field Radiation Levels Relevant for SEEs at the LHC” K. Roed et al, IEEE TNS, 2012
• “SEU Measurements and Simulations in a Mixed Field Environment”, R. Garcia Alia et al, IEEE TNS, 2013
• “Qualification and Characterization of SRAM Memories Used as Radiation Sensors in the LHC”. S. Danzeca et al, IEEE TNS, 2014
• “SEL Cross Section Energy Dependence Impact on the High Energy Accelerator Failure Rate”, R. Garcia Alia et al, IEEE TNS, 2014
• “A New RadMon Version for the LHC and its Injection Lines”, G. Spiezia et al, IEEE TNS, 2014
• “SEL Hardness Assurance in a Mixed Radiation Field”, R. Garcia Alia et al, IEEE TNS, 2015
• “CHARM: A Mixed Field Facility at CERN for Radiation Tests in Ground, Atmospheric, Space and Accelerator Representative Environments,“ J. Mekki et al, IEEE TNS 2016
• “Monte Carlo Evaluation of Single Event Effects in a Deep-Submicron Bulk Technology: Comparison Between Atmospheric and Accelerator Environment,” A. Infantino et al, IEEE TNS, 2017.
• “Single event effects in high-energy accelerators”, R. Garcia Alia et al, Semicond. Sci. Technol, 2017
• “High-energy Electron Induced SEUs and Jovian Environment Impact”, M. Tali et al, IEEE TNS, 2017
• “Simplified SEE Sensitivity Screening for COTS Components in Space”, R. Garcia Alia et al, IEEE TNS, 2017
• “LHC and HL-LHC: Present and Future Radiation Environment in the High-Luminosity Collision Points and RHA Implications,“ R. Garcia Alia et al, IEEE TNS, 2018