Radiation Risks and Mitigation in Electronic Systems

Electrical and electronic systems can be disturbed by radiation-induced effects. In some cases, radiation-induced effects are of a low probability and can be ignored; however, radiation effects must be considered when designing systems that have a high mean time to failure requirement, an impact on protection, and/or higher exposure to radiation. High-energy physics power systems suffer from a combination of these effects: a high mean time to failure is required, failure can impact on protection, and the proximity of systems to accelerators increases the likelihood of radiation-induced events. This paper presents the principal radiation-induced effects, and radiation environments typical to high-energy physics. It outlines a procedure for designing and validating radiation-tolerant systems using commercial off-the-shelf components. The paper ends with a worked example of radiation-tolerant power converter controls that are being developed for the Large Hadron Collider and High Luminosity-Large Hadron Collider at CERN.Comment: 19 pages, contribution to the 2014 CAS - CERN Accelerator School: Power Converters, Baden, Switzerland, 7-14 May 201

What are the evolutionary constraints on larval growth in a trophically transmitted parasite?

For organisms with a complex life cycle, a large larval size is generally beneficial, but it may come at the expense of prolonged development. Individuals that grow fast may avoid this tradeoff and switch habitats at both a larger size and younger age. A fast growth rate itself can be costly, however, as it requires greater resource intake. For parasites, fast larval growth is assumed to increase the likelihood of host death before transmission to the next host occurs. Using the tapeworm Schistocephalus solidus in its copepod first intermediate host, I investigated potential constraints in the parasite’s larval life history. Fast-growing parasites developed infectivity earlier, indicating there is no functional tradeoff between size and developmental time. There was significant growth variation among full-sib worm families, but fast-growing sibships were not characterized by lower host survival or more predation-risky host behavior. Parental investment also had little effect on larval growth rates. The commonly assumed constraints on larval growth and development were not observed in this system, so it remains unclear what prevents worms from exploiting their intermediate hosts more aggressively

Development of radiation tolerant components for the Quench Protection System at CERN

This paper describes the results of irradiation campaigns with the high resolution Analog to Digital Converter (ADC) ADS1281. This ADC will be used as part of a revised quench detection circuit for the 600 A corrector magnets at the CERN Large Hadron Collider (LHC) . To verify the radiation tolerance of the ADC an irradiation campaign using a proton beam, applying doses up to 3,4 kGy was conducted. The resulting data and an analysis of the found failure modes is discussed in this paper. Several mitigation measures are described that allow to reduce the error rate to levels acceptable for operation as part of the LHC QPS

Radiation tolerant power converter controls

The Large Hadron Collider (LHC) at the European Organisation for Nuclear Research (CERN) is the world's most powerful particle collider. The LHC has several thousand magnets, both warm and super-conducting, which are supplied with current by power converters. Each converter is controlled by a purpose-built electronic module called a Function Generator Controller (FGC). The FGC allows remote control of the power converter and forms the central part of a closed-loop control system where the power converter voltage is set, based on the converter output current and magnet-circuit characteristics. Some power converters and FGCs are located in areas which are exposed to beam-induced radiation. There are numerous radiation induced effects, some of which lead to a loss of control of the power converter, having a direct impact upon the accelerator's availability. Following the first long shut down (LS1), the LHC will be able to run with higher intensity beams and higher beam energy. This is expected to lead to significantly increased radiation induced effects in materials close to the accelerator, including the FGC. Recent radiation tests indicate that the current FGC would not be sufficiently reliable. A so-called FGClite is being designed to work reliably in the radiation environment in the post-LS1 era. This paper outlines the concepts of power converter controls for machines such as the LHC, introduces the risks related to radiation and a radiation tolerant project flow. The FGClite is then described, with its key concepts and challenges: aiming for high reliability in a radiation field

Development of radiation tolerant components for the Quench Protection System at CERN

This paper describes the results of irradiation campaigns with the high resolution Analog to Digital Converter (ADC) ADS1281. This ADC will be used as part of a revised quench detection circuit for the 600 A corrector magnets at the CERN Large Hadron Collider (LHC) . To verify the radiation tolerance of the ADC an irradiation campaign using a proton beam, applying doses up to 3,4 kGy was conducted. The resulting data and an analysis of the found failure modes is discussed in this paper. Several mitigation measures are described that allow to reduce the error rate to levels acceptable for operation as part of the LHC QPS

Alpha-Particle Induced Soft-Error Rate in CMOS 130 nm SRAM

2010 Conference on Radiation and its Effects on Components and Systems (RADECS), Langenfeld, GERMANY, SEP 20-24, 2010International audienceWe report the modeling and simulation of the soft-error rate (SER) in CMOS 130 nm SRAM induced by alpha-particle emission in silicon due to uranium contamination at ppb concentration levels. Monte-Carlo simulation results have been confronted to experimental data obtained from long-duration (>20 000 h) real-time measurements performed at the under-ground laboratory of Modane (LSM) and from experimental counting characterization using an ultra low background alpha-particle gas proportional counter. The calibration of simulations with the measured SER allowed us to determine a U-238 contamination level of 0.37 ppb (considered at secular equilibrium) in very good agreement with both corresponding alpha-particle emissivity levels measured and simulated at wafer-level in the range 1.1 to 2.3 x 10(-3) alpha/cm(2)/h

Geant4 Analysis of n-Si Nuclear Reactions From Different Sources of Neutrons and Its Implication on Soft-Error Rate

Conference on Radiation Effects on Components and Systems (RADECS)/Radiation Effects Data Workshop, Univ Sevilla, Escuela Super Ingenieros, Seville, SPAIN, SEP 19-23, 2011International audienceThis work examines nuclear events resulting from the interaction of atmospheric neutrons at ground level and different atmospheric-like sources with a silicon layer. Using extensive Geant4 simulations and in-depth data analysis, this study provides a detailed comparison between several facilities and natural environment in terms of nuclear processes, secondary ion production and fragment energy distribution. The different computed databases have been used in a second part of this work to estimate the Soft-Error Rate (SER) of a widely characterized 65 nm SRAM test circuit with the Tool suIte for rAdiation Reliability Assessment (TIARA Monte-Carlo simulation code). A detailed analysis is conducted to clarify the mechanisms leading to single and multiple cell upsets and to estimate the SER of a broad spectrum source from values obtained with monoenergetic simulations

Real-Time Soft-Error Testing of 40nm SRAMs

IEEE International Reliability Physics Symposium (IRPS), Anaheim, CA, APR 15-19, 2012International audienceThis work reports the real-time Soft-Error Rate (SER) characterization of more than 7 Gbit of SRAM circuits manufactured in 40 nm CMOS technology and subjected to natural radiation (atmospheric neutrons). This experiment has been conducted since March 2011 at mountain altitude (2552 m of elevation) on the ASTEP Platform. The first experimental results, cumulated over more than 7,500 h of operation, are analyzed in terms of single bit upset, multiple cell upsets, physical bitmap and convergence of the SER. The comparison of the experimental data with Monte Carlo simulations and accelerated tests is finally reported and discussed

Systems overview: Power Converter and their Controls

In this paper, performance of power converters for the Run 2 of the Large Hadron Collider (LHC) is evaluated. This contribution focuses on the availability of different families of power converters, their evolution, analyses known failure modes and discusses mitigation of failures in the future. The last section describes new deployments and consolidation during the Long Shutdown 2 (LS2) and their impact on hardware commissioning for the Run 3