Slawosz Uznanski

SEL Hardness Assurance in a Mixed Radiation Field

This paper explores the relationship between monoenergetic and mixed-field Single Event Latchup (SEL) cross sections, concluding that for components with a very strong energy dependence and highly-energetic environments, test results from monoenergetic or soft mixed-field spectra can significantly underestimate the operational failure rate. We introduce a semi-empirical approach that can be used to evaluate the SEL rate for such environments based on monoenergetic measurements and information or assumptions on the respective sensitive volume and materials surrounding it. We show that the presence of high-Z materials such as tungsten is particularly important in determining the hadron cross section energy dependence for components with relatively large LET thresholds.

Combining GEANT4 and TIARA for Neutron Soft Error-Rate Prediction of 65 nm Flip-Flops

Experimental neutron characterizations of standard and radiation-hardened-by-design (RHBD) flip-flops (FFs) are compared to combined GEANT4 and TIARA simulations. Good agreement is found between experiment and simulation for both architectures exhibiting soft error-rate (SER) values ranging over more than two decades. In-depth analysis of TIARA simulation results demonstrates that different underlying mechanisms are at the origin of observed soft errors: neutron-silicon (n-Si) elastic scattering for standard 65 nm FF while multiproduct nuclear reactions are for the RHBD structure. Finally, TIARA simulation results for monoenergetic neutron sources and atmospheric-like (i.e., synthetic) neutron spectra are discussed together with their impact on SER.

Energy Dependence of Tungsten-Dominated SEL Cross Sections

The energy dependence of proton-induced Single Event Latchup (SEL) failures is investigated for different Static Random Access Memories (SRAMs) and an Analog-to-Digital Converter (ADC) through experimental measurements in the 30-230 MeV range. It is observed that for several of them, the measurements are not compatible with a saturation below the maximum energy tested. A Monte Carlo based model is proposed that explains the observed cross section increase through the presence of tungsten near the sensitive region and is used to extrapolate the SEL cross section to larger energies. The significant cross section increases expected by the model up to 3 GeV are quantified and discussed, potentially having a strong impact on the failure rate for energetic environments such as high-energy accelerators or the avionics contexts.

SEE Measurements and Simulations Using Mono-Energetic GeV-Energy Hadron Beams

Single Event Upset (SEU) measurements were performed on the ESA SEU Monitor using mono-energetic GeV-energy hadron beams available in the North Experimental Area at CERN. A 400 GeV proton beam in the H4IRRAD test area and a 120 GeV mixed pion and proton beam at the CERN-EU high Energy Reference Field facility (CERF) were used for this purpose. The resulting cross section values are presented and discussed as well as compared to the several hundred MeV case (typical for standard test facilities) from a physical interaction perspective with the intention of providing a more general understanding of the behavior. Moreover, the implications of the cross section dependence with energy above the several hundred MeV range are analyzed for different environments. In addition, analogous measurements are proposed for Single Event Latchup (SEL), motivated by discussed simulation results. Finally, a brief introduction of the future CHARM (CERN High-energy AcceleratoR Mixed facility) test installation is included.

SEL Cross Section Energy Dependence Impact on the High Energy Accelerator Failure Rate

We use a single event latchup (SEL) model calibrated to heavy ion (HI) and proton data below 230 MeV to extrapolate the proton cross section to larger energies and evaluate the impact of the potential cross section increase with energy on the SEL rate in different environments. We show that in the case of devices with a large LET onset for HI and a certain amount of tungsten near the sensitive volume (SV), the calculated failure rates for energetic environments based on monoenergetic test data can significantly underestimate the real value. In addition, we show through measurements using a 480 MeV beam and an inspection of the devices architecture that the model was successful in estimating the SEL cross section and tungsten volume per cell.

The Effect of Proton Energy on SEU Cross Section of a 16 Mbit TFT PMOS SRAM with DRAM Capacitors

Proton experimental data are analyzed for a 16-Mbit thin-film-transistor (TFT) PMOS static random access memory (SRAM) with DRAM capacitors. The presence of high-Z materials as tungsten causes an unusual increase of the single event upset (SEU) proton cross section for the energies above 100 MeV. Monte-Carlo simulations reproduce the experimentally measured cross sections up to 480 MeV and predict a further increase up to GeV energies. The implications of this increase are analyzed in the context of the LHC and other radiation environments where a significant fraction of the fluence lies above 100 MeV.

Radiation tolerant power converter controls

The Large Hadron Collider (LHC) at the European Organisation for Nuclear Research (CERN) is the worlds 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 accelerators 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.

Heavy Ion Characterization and Monte Carlo Simulation on 32 nm CMOS Bulk Technology

Heavy ion experimental test results carried out on static random-access memories (SRAMs) manufactured in bulk complementary metal-oxide semiconductor (CMOS) 32 nm are compared to Monte Carlo simulations. Additional simulation capabilities allow for insight in heavy ion cross-section variations as a function of temperature, power supply voltage, and process corners. Monte Carlo simulations of a radiation-hardened-by-design flip-flop based on a dual-interlocked storage cell latch have been performed and show similar sensitivities for 65 nm and 32 nm technologies. Finally, for the first time, the heavy-ion cross-section of the 20 nm bulk CMOS SRAMs is anticipated by simulation by using the latest available technology data.

COTS FPGA/SRAM irradiations using a dedicated testing infrastructure for characterization of large component batches

This paper introduces a new testing platform for irradiation of large batches of COTS FPGA and SRAMs. The main objective is measurement of component radiation response and assessment of component-to-component variability within one batch. The first validation and test results using the testing platform are presented for 150nm TFT SRAM (Renesas) and different sizes of the 130nm ProASIC3 FPGA (Microsemi).

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.