FLUKA Monte Carlo simulations have been performed to identify particle energy spectra and fluences relevant for evaluating the risk of single event effects in electronics installed in critical LHC ...underground areas. Since these simulations are associated with significant uncertainties, the results will compared with an online monitoring system installed to evaluate radiation levels at the location of the electronics. This comparison approach have been benchmarked in a mixed field reference facility and for a preliminary LHC monitoring case study.
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.
Multi-needle Langmuir probes are mounted on satellites and sounding rockets for high-frequency characterization of plasma in the ionosphere. Mounted on a spacecraft, the recorded probe current often ...differs from expected results. In this paper, we perform a numerical study using a particle in cell model to see how the spacing between the individual probes used in a multi-needle setup influences the measured current. We also study how the applied probe bias voltage can contribute to deviations. In our study, we use realistic electron temperatures and electron densities for the relevant part of the ionosphere. However, the results should be generally applicable and valid for other space environments as well as for laboratory Langmuir probe applications. From our study, we can see that when the distance is short, less than two Debye lengths, the current is highly affected, and we can see deviations of more than 60% compared to a single probe setup.
The radiation tolerance of isotopic enriched and natural silicon carbide junction barrier Schottky diodes are compared under heavy ion irradiation. Both types of devices experience leakage current ...degradation as well as single-event burnout events. The results were comparable, although the data may indicate a marginally lower thresholds for the isotopic enriched devices at lower linear energy transfer (LET). Slightly higher reverse bias threshold values for leakage current degradation were also observed compared to previously published work.
We present a numerical study disclosing non-linear effects and hysteresis loops for a swept bias Langmuir probe. A full kinetic particle in cell (PIC) model has been used to study the temporal sheath ...effects and the probe current. Langmuir probes are normally operated at low frequencies, since a "close to steady state" condition is required to characterize the plasma. However, during operations above frequencies normally used, capacitive and non-linear resistive effects are being unveiled. We demonstrate how ion and electron density and temperature change properties of the probe-plasma system. We also show that a swept Langmuir probe exhibits essential properties described as the "fingerprint of memristors" and how a Langmuir probe can be identified as a transversal memristor. Understanding non-linear processes might enable new ways to operate Langmuir probes with higher sampling rates and better accuracy.
The formation time of the surrounding sheath of Langmuir probes in an ionospheric plasma has been studied to better understand the constraints this puts on the sampling frequency of a probe. A fully ...kinetic three-dimensional particle-in-cell model is used to simulate the temporal effects in the electron saturation region as the sheath forms. The stability of the probe current and the stability of the ion and electron density in the vicinity of the probe have been used to evaluate when the sheath was formed. Simulated results were compared with theoretical models and are in good agreement with the theoretical results. This shows that theoretical models can be used as guidance to estimate the formation time and to determine the sampling rate for a swept bias Langmuir system. Our results also show that the formation time is less affected by the plasma temperature and bias voltage as we move into the thick sheath regime, and will instead be determined by the plasma density. The presented results also show that applying a step function to the probe could be used to characterise ions species composition, or to estimate the ion density.
We perform Monte Carlo (MC) simulations to describe heavy ion (HI) nuclear interactions in a broad energy range (4 MeV/n-150 GeV/n), focusing on the single event effect (SEE) sub-linear energy ...transfer (LET) impact. Previously retrieved single event latch-up (SEL) experimental data have indicated that standard energy ions (~10 MeV/n) can produce high-LET secondaries through fusion reactions which are expected to strongly influence the SEE cross section in the sub-LET region. Alternatively, interactions of higher energy ions (>100 MeV/n) yield secondaries of a similar LET distribution as from the projectile, for projectile-like fragments, and high-energy proton reactions, for target-like fragments. Hence, the factor of relevance to the sub-LET SEE cross section is correlated to low-energy.
Ultrahigh-energy (UHE) heavy ions show various advantages at testing single-event effect (SEE) in modern technologies, due to their highly penetrating nature. However, the intercepting material in ...the beam line contributes to the modification of the beam structure by generation of fragments produced via nuclear interactions. This is especially relevant for UHE heavy ion beams, representative of energies in space, which are not fully investigated through conventional ground-level testing. This article is dedicated to the study of the longitudinal energy deposition mechanisms in silicon by the aforementioned heavy ion beams and their fragments. The presented studies have been carried out using Monte Carlo simulations triggered by experimentally observed phenomena.
Single event effects in high-energy accelerators Alía, Rubén García; Brugger, Markus; Danzeca, Salvatore ...
Semiconductor science and technology,
03/2017, Letnik:
32, Številka:
3
Journal Article
Recenzirano
Odprti dostop
The radiation environment encountered at high-energy hadron accelerators strongly differs from the environment relevant for space applications. The mixed-field expected at modern accelerators is ...composed of charged and neutral hadrons (protons, pions, kaons and neutrons), photons, electrons, positrons and muons, ranging from very low (thermal) energies up to the TeV range. This complex field, which is extensively simulated by Monte Carlo codes (e.g. FLUKA) is due to beam losses in the experimental areas, distributed along the machine (e.g. collimation points) and deriving from the interaction with the residual gas inside the beam pipe. The resulting intensity, energy distribution and proportion of the different particles largely depends on the distance and angle with respect to the interaction point as well as the amount of installed shielding material. Electronics operating in the vicinity of the accelerator will therefore be subject to both cumulative damage from radiation (total ionizing dose, displacement damage) as well as single event effects which can seriously compromise the operation of the machine. This, combined with the extensive use of commercial-off-the-shelf components due to budget, performance and availability reasons, results in the need to carefully characterize the response of the devices and systems to representative radiation conditions.
Single Event Upset (SEU) measurements were performed using the European Space Agency's (ESA) Standard SEU Monitor in the H4 Irradiation mixed-field test area at CERN. The results, tightly correlated ...with the radiation environment, are compared with those obtained with the CERN Radiation Monitors (RadMons) as well as with the Monte Carlo simulation of the experimental setup using the FLUKA Monte Carlo transport code. In addition, the SEU cross section of the device for particles and energies not available in standard testing (such as charged pions or GeV-energy hadrons) are simulated and discussed, showing an increase of over a factor 2 for nucleons in the 200 MeV-3 GeV range. A monoenergetic SEU cross section measurement at 120 GeV is included in the analysis.
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