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Digital pulse shape discrimination (PSD) systems are widely used to extract various kinds of information from the shape of output pulses of radiation detectors. Such systems replace the traditional analog PSD circuits with numerical algorithms running on a digital processor, which makes them more flexible for implementing various PSD methods. However, the available digital PSD algorithms have been generally tailored to the characteristics of the concerned detectors, which limit their general use. Here, for the purpose of building a general-purpose digital PSD module, we present a PSD algorithm that, with minimum alterations, can be used with a wide range of radiation detectors. Our approach is based on using the cosine similarity measure to quantify the variations in the shape of detectors’ pulses with respect to the shape of a unit step pulse. The method is described in detail, and the results of the test experiments with different types of radiation detectors, including a boron tetrafluoride (BF3) proportional counter, a liquid scintillation detector, and high purity germanium (HPGe) detector are shown. The performance of the algorithm is also compared to that of the common rise time discrimination method. [ABSTRACT FROM AUTHOR]

Radiological source search is a challenge involving the detection, identification, and localization of weak sources within background environments that vary both spatially and temporally. In this paper, a method for simultaneously detecting and identifying gamma-ray sources using background models formed from spectral data is described. Non-negative matrix factorization (NMF) is used to generate low-dimensional representations of gamma-ray spectra, allowing for a compact means of capturing variation in gamma-ray backgrounds. Background models formed using NMF are used to perform anomaly detection, and additionally, models are augmented with spectral templates of gamma-ray sources to perform simultaneous detection and identification using a likelihood ratio test. The NMF-based detection and identification algorithm is benchmarked against a standard Region of Interest algorithm and shows significant performance gains. In addition, NMF-based anomaly detection shows improvements over methods based on gross counts or principal component analysis. Algorithm performance is evaluated using unshielded sources with activities between 5 and 400 ${\mu }$ Ci at a standoff distance of 20 m using source injection on background data collected using a 1 m2 NaI array on the Radiological Multisensor Analysis Platform. [ABSTRACT FROM AUTHOR]

To overcome the shortcomings of the traditional staircased particle-in-cell (PIC) method, this paper presents the conformal PIC method to simulate the system-generated electromagnetic pulse (SGEMP) produced by the X-ray beam. One advantage of this method is to accurately simulate the electromagnetic response from the boundary of the object, and more importantly, it can be used to simulate the emission direction of the electrons accurately by properly handling the normal direction of the curved boundary. The numerical results show that the conformal PIC method can save much more computation time and memory than the staircased PIC technique to obtain the same accurate computational results. [ABSTRACT FROM AUTHOR]

This paper analyses the neutron irradiation impact on the electrical performances of unstressed, ON-state, OFF-state, and negative gate bias (NGB) stressed AlInN/GaN HEMTs. These irradiations have resulted in the creation of electron traps that are causing a decrease in the drain current and an increase in the access resistance of the unstressed, ON-state, or OFF-state stressed AlInN/GaN devices. These degradations have been correlated with gamma spectrometry measurements and transmutation reactions occurred during the thermalized neutron irradiation have been highlighted. Despite these phenomena, a rise in drain current and a reduction in access resistance have been observed when NGB stressed AlInN/GaN HEMTs were irradiated with a fluence of $1.2\times 10^{\mathbf {12}}$ neutrons/cm2. The differences between the electrical behaviors of unstressed, ON-state, OFF-state, and NGB stressed devices observed after the neutron bombardment are related to the presence of electron traps in these device structures. [ABSTRACT FROM AUTHOR]

The breakdown voltage (BVDS) variation of 400-V silicon-on-insulator (SOI) n-channel laterally diffused metal–oxide–semiconductor field-effect transistors (NLDMOSFETs) is examined after exposure to a total ionizing dose (TID). The results for OFF bias and ON bias are explored. For the OFF bias, BVDS increases first and then degrades with accumulated dose. For the ON bias, the irradiated device shows soft breakdown after irradiation. The physical mechanisms for these variations are analyzed and confirmed by technology computer-aided design (TCAD) simulation. [ABSTRACT FROM AUTHOR]

This paper presents the results of investigations on the susceptibility of routing network in SRAM-based field-programmable gate arrays (FPGAs) exposed to ionizing neutron radiation creating single-event upset (SEU). A method to configure test circuits mostly with routing resources and few logic resources is presented. Full control over routing resources enables the use of different interconnection types in order to create routing-based oscillators. A method is proposed to route through the 2-D array of switch matrices inside the interconnection network and to automatically identify the involved programmable interconnection points associated with a node. An experimental setup employed to measure delay changes (DCs) induced by single-event upset to the FPGA routing resources, while it is exposed to ionizing neutron radiation, is described. The proposed setup requires no external equipment instruments for DC measurement. The experimental results show that our setup is able to measure induced DCs as low as 5 ps on higher frequency oscillators. Statistical data such as cross sections and mean time to DC are extracted from the results. [ABSTRACT FROM AUTHOR]

Commercial off-the-shelf microcontrollers can be useful for noncritical processing on spaceborne platforms. These microprocessors can be inexpensive and consume small amounts of power. However, the software running on these processors is vulnerable to radiation upsets. In this paper, we present a fully automated, configurable, software-based tool to increase the reliability of microprocessors in high-radiation environments. This tool consists of a set of open-source LLVM compiler passes to automatically implement software-based mitigation techniques. We duplicate or triplicate computations and insert voting mechanisms into software during the compilation process, allowing for runtime error correction. While the techniques we implement are not novel, previous work has typically been closed source, processor architecture dependent, not automated, and not tested in real high-radiation environments. In contrast, the compiler passes presented in this paper are publicly available, highly customizable, and are platform independent and language independent. We have tested our modified software using both fault injection and through neutron beam radiation on a Texas Instruments MSP430 microcontroller. When tested by a neutron beam, we were able to decrease the cross section of programs by $17-29\times $ , increasing mean-work-to-failure by $4-7\times $. [ABSTRACT FROM AUTHOR]

We report on photoluminescence (PL) spectroscopy and transmission electron microscope imaging of suspended and substrate-supported flakes of the 2-D semiconductor MoS2 before and after exposure to 100-keV proton radiation with fluences of $6 \times 10^{13}$ , $6\times 10^{14}$ , and $6 \times 10^{15}$ p/cm2, respectively, and subsequent annealing. An indirect-to-direct bandgap transition is observed, which is preserved after annealing. This transition is accompanied by an unexpected increase in PL intensity after radiation exposure of multilayer samples, which is attributed to higher radiative efficiency of the direct-gap transition. [ABSTRACT FROM AUTHOR]

Neural networks are becoming an attractive solution for automatizing vehicles in the automotive, military, and aerospace markets. Thanks to their low-cost, low-power consumption, and flexibility, field-programmable gate arrays (FPGAs) are among the promising devices to implement neural networks. Unfortunately, FPGAs are also known to be susceptible to radiation-induced errors. In this paper, we evaluate the effects of radiation-induced errors in the output correctness of two neural networks [Iris Flower artificial neural network (ANN) and Modified National Institute of Standards and Technology (MNIST) convolutional neural network (CNN)] implemented in static random-access memory-based FPGAs. In particular, we notice that radiation can induce errors that modify the output of the network with or without affecting the neural network’s functionality. We call the former critical errors and the latter tolerable errors. Through exhaustive fault injection, we identify the portions of Iris Flower ANN and MNIST CNN implementation on FPGAs that are more likely, once corrupted, to generate a critical or a tolerable error. Based on this analysis, we propose a selective hardening strategy that triplicates only the most vulnerable layers of the neural network. With neutron radiation testing, our selective hardening solution was able to mask 40% of faults with a marginal 8% overhead in one of our tested neural networks. [ABSTRACT FROM AUTHOR]

Silicon-on-insulator latch designs and layouts that are robust to multiple-node charge collection are introduced. A general Monte Carlo radiative energy deposition (MRED) approach is used to identify potential single-event susceptibilities associated with different layouts prior to fabrication. MRED is also applied to bound single-event testing responses of standard and dual interlocked cell latch designs. Heavy ion single-event testing results validate new latch designs and demonstrate bounds for standard latch layouts. [ABSTRACT FROM AUTHOR]

Lighter doping, pretreatment (exposure to hydrogen in a steam bath), and lower dose rate are each found to exacerbate 10-keV X-ray-induced negative frequency shifts and increase in resistivity measured in T-shaped, asymmetric, piezoresistive, micromachined, and resonating cantilevers. All devices recover to levels close to preirradiation after several hours of postirradiation annealing. The effects are attributed to dose-rate-dependent efficiencies of the depassivation of dopants by hydrogen and surface charging effects, which alter the effective Young’s modulus and shear elastic constants. Increases in resistivity are attributed to increases in scattering causing decreases in mobility. Results indicate the need to consider dopant type and concentration when choosing microelectromechanical systems for use in radiation environments in addition to accounting for low-dose-rate effects. [ABSTRACT FROM AUTHOR]

$3 \times 10^{13}/\text{cm}^{2}$ 1.2-MeV proton radiation will significantly increase heavy ion single-event transient (SET) cross sections and pulsewidths in 65-nm bulk CMOS technology. After proton radiation, heavy ion SET sensitivity increase in N-hit blocks is more than that in P-hit blocks. The analysis suggests that pMOS transistor on current ($I_{\mathrm{\scriptscriptstyle ON}}$) reduction due to total ionizing dose effects is the main reason for this effect. It is suggested that alternate heavy ion and proton experiments should be performed for radiation hardness assurance of candidate electronic devices used in deep space missions. [ABSTRACT FROM AUTHOR]

Data Device Corporation’s SCS750 single-board computers (SBCs) have been operating without interruption onboard the Gaia satellite since its launch in 2014. The uninterrupted operation is possible because of several hardening techniques that allow the SBC to correct single-event upsets (SEUs) in the constituent components. We present on-orbit SEU data for the SBCs. All errors analyzed here were corrected by the SBC and had no effect on mission operation. We analyze the data to determine the accuracy of current models, as well as the effects of the space weather environment. [ABSTRACT FROM AUTHOR]

The response of Fricke xylenol orange gelatin dosimeter has been studied to investigate the possibility of achieving a calibration method based on a preirradiation procedure. With this aim, different preirradiation parameters have been tested, and the system response to subsequent irradiations has been investigated. Both Fricke gel layers and cuvettes were considered, and no dependence on shape and wall material was observed. An increase of the system response was observed, depending on the total absorbed dose and not on the number of subsequent irradiations performed, as evidenced by the changes of the absorption spectra shapes. Moreover, different calibration curves, and consequently different sensitivities, were obtained with different preirradiation parameters. In order to propose a calibration procedure, further studies are of fundamental importance to deeper comprehending the influence of preirradiation parameters on the system sensitivity and response. In particular, a systematic analysis of the whole absorption spectra has proved to be central. [ABSTRACT FROM AUTHOR]

To decommission the Fukushima nuclear power plant after the accident caused by a tsunami in 2011, characterization of the fuel debris is required. The precise location and radiological composition of the fuel debris are currently unknown, and the area is submerged making it difficult to investigate the primary containment vessel. An integrated system that includes both radiation detectors and sonar will allow the full localization and characterization of the fuel debris. This paper describes research completed toward the development of a complete system, on-board a low-cost, small form-factor, submersible remotely operated vehicle. A cerium bromide (CeBr3) scintillator detector for dose-rate monitoring and gamma-ray spectrometry has been integrated and validated experimentally with a 137Cs source, both in the laboratory and while submerged. The addition of an Imagenex 831L sonar has enabled technical demonstrations to take place at the National Maritime Research Institute’s facility in Japan, where the system was able to characterize the shape and size of synthetic core debris. The combination of geometrical and radiological measurements allows the real-time localization of fuel debris and isotope identification, leading to an invaluable source of information to the workers at Fukushima that will enable increased efficiency and reduce risk during the decommissioning of the site. [ABSTRACT FROM AUTHOR]

MOSFET can operate as a radiation detector mainly in high-energy photon beams that are normally used in cancer treatments. In general, such an electronic device can work as a dosimeter from the threshold voltage shift measurements. The purpose of this paper is to show a new way for measuring the dose response of MOSFETs when they are under an X-ray beam generated from a 100-kV potential range, which is normally used in diagnostic radiology. Basically, the method consists of measuring the MOSFET drain current as a function of the radiation dose. For this type of device, it has to be biased with a high-value resistor aiming to see a substantial change in the drain current after it has been irradiated with an amount of radiation dose. Two types of n-channel devices were used in the experiment: a signal transistor and a power transistor. The delivered dose to the device was varied, and the electrical curves were plotted. In addition, a sensitivity analysis of the power MOSFET response was made by varying the tube potential of about 20%. The results show that both types of devices have very similar responses, and the shift in the electrical curve is proportional to the radiation dose. Unlike the power MOSFET, the signal transistor does not provide a linear function between the dose rate and its drain current. We have also observed that the variation in the tube potential of the X-ray equipment produces a very similar dose response. [ABSTRACT FROM AUTHOR]

The presence of Te secondary-phase defects (i.e., Te inclusions and Te precipitates) is a major factor limiting the performance of CdZnTe (CZT) X-ray and gamma-ray radiation detectors. We find that Te secondary-phase defects in CZT crystals can be removed through postgrowth two-step annealing without creating new trapping centers (i.e., prismatic punching defects). Two-step annealing (with the first under a Cd pressure and the second one under a Te pressure) was demonstrated to be effective in removing the Te secondary-phase defects, while preserving the electrical resistivity of the CZT detector. The first step involves annealing of semi-insulating CZT under a Cd overpressure at 700 °C/600 °C (CZT/Cd) for 24 h, which completely eliminated the Te-rich secondary-phase defects (Te inclusions). However, it resulted in a lower resistivity of the samples (down to $2\times 10^{4-6}\,\,\Omega \cdot \text {cm}$). A subsequent annealing step involves processing CZT under a Te ambient condition at 540 °C/380 °C (CZT/Te) for 120 h, which restored the crystal’s resistivity to $6.4 \times 10^{10}\,\,\Omega \cdot \text {cm}$ without creating new Te secondary-phase defects. However, Te inclusions reappeared in the case of unnecessarily long Te ambient annealing. Pulse-height spectra taken with the two-step annealed CZT detectors showed an improved detector performance due to a reduced concentration and the size of Te secondary-phase defects. [ABSTRACT FROM AUTHOR]

This paper reports an extensive assessment of widely used evaluated atomic data libraries released in ENDF/B-VIII.0 and in EPICS2017 in early 2018. The new versions are intended to replace the data libraries currently used by major Monte Carlo particle transport codes to model electron and photon interactions with matter, which date back to the 1990s. The evaluation is performed from a user perspective and concerns various characteristics of the data, including their intrinsic consistency, the differences across their various formats and distribution sources, and the effects on computational performance associated with their use. The results of the tests demonstrate the impact of using the new data libraries in a Monte Carlo simulation environment and highlight some opportunities for improvement in future versions. [ABSTRACT FROM AUTHOR]

In this paper, the design of a power-ON-reset intellectual property (IP) block for the RD53 collaboration, a radiation hardening by design circuit to withstand the High-Luminosity Large Hadron Collider tracker radiation environment, is presented. In this environment, the performance of the IP block under radiation must be ensured for a total ionizing dose up to 500 Mrad and possible ions interaction for a linear energy transfer of 15 MeV/cm2/mg. To verify the radiation hardness of the presented circuit, an automatic single-event effect sensitivity tool (Analog Fault Tolerant University of Seville Hardware Debugging System) has been used to perform a complete analysis over it, and also several experiments have been performed to test the designed blocks and obtain the final IP qualification. [ABSTRACT FROM AUTHOR]

This paper evaluates the error rate of a memory-bound application implemented in different commercial-off-the-shelf multicore and many-core processors. To achieve this goal, two quantitative experiments are performed: fault-injection campaigns and radiation ground testing. In addition, this paper proposes an approach for predicting the application error rate by combining the results issued from both types of experiments. The usefulness of the approach is illustrated by three case studies implemented in processors having different manufacturing technologies and architectures: 45-nm silicon-on-insulator (SOI) free-scale P2041 quad-core processor, 65-nm CMOS Adapteva Epiphany multicore processor, and 28-nm CMOS Kalray multipurpose processing array-256 many-core processor. The reliability of the processors for avionics is obtained from their experimental error rates extrapolated to avionic altitudes. Reliability curves are plotted for observing the prediction accuracy. A comparison of the failure in time of the selected processors shows that the greater single-event effect vulnerability of CMOS technology compared with the SOI one can be compensated with the implementation of effective error detection and correction. These protection mechanisms allow the use of CMOS devices having huge memory capacity in applications operating in severe radiation environments. [ABSTRACT FROM AUTHOR]

This paper presents our achievement in the development of new types of advanced composite scintillators (CSs) based on the single crystalline films (SCFs) of Lu3Al5O12 (LuAG) garnet, doped with Pr3+ and Sc3+ ions, and substrate from single crystals (SCs) of Ce3+-doped LuAG using the technology of liquid phase epitaxy. We show the possibility of the simultaneous registration of $\alpha$ -particles and $\gamma$ -quanta by means of separation of the decay kinetics of SCF and crystal parts of such CSs. Namely, the significant differences in the scintillation decay kinetics of LuAG:Pr SCF/LuAG:Ce SC and LuAG:Sc SCF/LuAG:Ce SC CSs under excitation by $\alpha$ -particles of 241Am (5.5 MeV) source and $\gamma$ -quanta of 137Cs (662 keV) source are observed. Thus, such types of CSs can be successfully applied for separation of the signals coming from their film and crystal parts at the registration of the mixed radiation fluxes of $\alpha$ -particles and $\gamma$ -quanta. [ABSTRACT FROM AUTHOR]

The radiation spectra in the CERN Large Hadron Collider (LHC) ranges from gigaelectronvolts down to thermal neutron levels. It is known that the thermal neutrons can significantly affect the electronic devices and systems exposed to the radiation environment of the tunnel and the shielded areas of the LHC. CERN’s radiation monitoring (RadMon) system uses static random access memories (SRAMs) to measure the contributions to the spectrum from both the high-energy hadrons (>20 MeV) and thermal neutrons. The knowledge of the SRAM thermal neutron cross section is required for evaluating their contribution to the particle spectra and thus identifying the thermal neutron critical area. This paper describes a procedure to acquire, by means of RadMon system, the thermal neutron cross section of SRAM memories in a mixed-field environment. The capabilities of the CERN High AcceleRator Mixed-field facility (CHARM) to measure the thermal neutron sensitivity are then investigated. The procedure is evaluated by comparing the thermal neutron cross sections obtained at CHARM and the one measured using a pure thermal neutron beam. The same procedure could be applied to other devices to understand their susceptibility. [ABSTRACT FROM AUTHOR]

As the minimum feature size on an integrated circuit continues to shrink aggressively toward deep submicrometer, the radiation-induced single-event (SE) upset (SEU) has become a prominent concern. Various radiation-hardening-by-design (RHBD) techniques have been developed to achieve a satisfactory SE tolerance for flip-flop (FF) designs. To enable low supply voltage for ICs and overcome the “power wall,” the lowest power consumption of different RHBD techniques to meet the target SEU cross section is studied in this paper. A comparative analysis of three representative RHBD FFs and an unhardened FF fabricated at the 14-/16-nm bulk FinFET CMOS technology generation shows that at least $2\times $ power dissipation reduction may be achieved by using RHBD FFs at appropriate supply voltage without degrading SE tolerance. [ABSTRACT FROM AUTHOR]

An improved total ionizing dose model for lateral p-n-p bipolar junction transistors is described. The model captures the impact of charged defects on radiation-induced excess base current. Failure to incorporate this mechanism in model underestimates gain degradation. [ABSTRACT FROM AUTHOR]

The radiation response of complementary metal–oxide–semiconductor (CMOS) gate oxides is typically insensitive to true dose-rate effects, but damage in deep-sub-micrometer technologies is dominated by ionization mechanisms in thick isolation oxides surrounding the transistors. Recent results in 65-nm FETs demonstrated that performance degradation in ultrahigh total ionizing dose (TID) experiments is due to defects in the isolation shallow trench isolation oxide or in the materials composing the lightly doped drain spacers. These insulators are thick, deposited, and crossed by a low electric field, characteristics similar to those typical of passivation oxides in linear bipolar technologies for which an enhanced low-dose-rate sensitivity (ELDRS) has been observed and systematically studied. We report in this paper the clear evidence of a dose-rate sensitivity of the TID-induced damage in both 130- and 65-nm CMOS technologies exposed to different radiation sources (X-rays and $\gamma $ -rays from a 60Co source). This sensitivity is attributed to mechanisms similar to those explaining ELDRS in bipolar devices and represents a significant challenge to the definition of a qualification procedure for circuits to be used in extreme radiation environments. [ABSTRACT FROM AUTHOR]

The existence of buried oxide (BOX) layer and the strong coupling effect between the front and back channels can worsen the radiation-induced degradation on fully depleted silicon-on-insulator (FDSOI) device. To mitigate the radiation impact, a new structure named double SOI is introduced in this paper. This new structure exhibits potential benefits of reducing the radiation-induced degradation effectively and independently, thanks to the additional electrode, which can be used to control the internal electrical field of the BOX layer. With this structure, FDSOI device parameter degradation due to total dose is studied, and some abnormal phenomena, such as the transconductance hump and the mobility enhancement, are observed and discussed. Sentaurus TCAD simulations are used for further analysis. Moreover, the impact of negative back-gate bias to transistor parameter degradation is investigated, and an improved back-gate compensation strategy is proposed. Technology improvement such as thinning the BOX on total ionizing dose (TID) amelioration is also discussed with TCAD simulation. [ABSTRACT FROM AUTHOR]

The existence of high-energy ($E > 1$ MeV) electrons in the inner zone is always a debatable issue. This paper aims at answering this question using both simulation-based and data-based measurement evidences. First, using NOAA measurements, in particular a proton channel contaminated by $E > 1.2$ MeV electrons, the slot filling was studied over solar cycles. Then, the found profiles were compared with the CRRES and SAMPEX measurements. Finally, using a simplistic physical model derived from Salammbô, the variations were estimated to understand the long-term behavior of the electrons in the inner belt. [ABSTRACT FROM AUTHOR]

This paper analyzes the suitability of single-instruction multiple data (SIMD) extensions of current microprocessors under radiation environments. SIMD extensions are intended for software acceleration, focusing mostly in applications that require high computational effort, which are common in many fields such as computer vision. SIMD extensions use a dedicated coprocessor that makes possible packing several instructions in one single extended instruction. Applications that require high performance could benefit from the use of SIMD coprocessors, but their reliability needs to be studied. In this paper, NEON, the SIMD coprocessor of ARM microprocessors, has been selected as a case study to explore the behavior of SIMD extensions under radiation. Radiation experiments of ARM CORTEX-A9 microprocessors have been accomplished with the objective of determining how the use of this kind of coprocessor can affect the system reliability. [ABSTRACT FROM AUTHOR]

The scintillation characteristics of Czochralski-grown GdLu2Al2Ga3O12:Ce and GdY2Al2Ga3O12:Ce single crystals were compared for $\gamma$ -ray detection. At 662-keV $\gamma$ -rays, light yield (LY) of 30700 photons/MeV obtained for GdLu2Al2Ga3O12:Ce is higher than that of 27200 photons/MeV obtained for GdY2Al2Ga3O12:Ce, while its energy resolution is inferior (14% versus 10.6%) due to a larger nonproportionality of LY. Scintillation decays were measured using the time-correlated single photon counting technique. A fast component decay time of 48 ns with relative intensity of 71% obtained for GdLu2Al2Ga3O12:Ce is superior to that of 106 ns (57%) for GdY2Al2Ga3O12:Ce. The coincidence time spectrum was measured in reference to a fast BaF2 scintillator, and coincidence time resolution was discussed. [ABSTRACT FROM AUTHOR]

The extraction of scintillation light from an inorganic scintillator is one of the major bottlenecks in time-of-flight positron emission tomography (ToF-PET) because it directly affects the energy and time resolution of the gamma detector. To increase the light extraction efficiency, we use photonic crystal slabs (PCS), defined as thin dielectric layers structured with a 2-D, or 3-D, periodic pattern. A higher light output, combined with a reduction of the average path length traversed by the photons in the crystal before extraction, leads to a more precise evaluation of the particle time detection. This also implies a better coincidence time resolution (CTR). These improvements translate to ToF-PET reconstructed images with a higher signal-to-noise ratio and lead to more accurate diagnoses, faster exams, and possibly a reduced patient radiation dose. In this paper, we present the results obtained using lutetium-yttrium oxyorthosilicate, Lu2(1-x)Y2xSiO5 samples patterned with nanoimprinted PCS. Comparative light yield (LY) measurements show an improvement of a factor 1.68 for a naked configuration, whereas CTR goes from 535 to 315 ps. [ABSTRACT FROM AUTHOR]

Qualification of safety instrumentation for nuclear reactors is a challenging issue in harsh radiation environments; the task is further complicated when new technologies are introduced. In this paper, we present two qualification strategies for new developments qualified to the highest safety standards. In the first case study, we develop a qualification method that quantifies the aging rate of a polymer during different aging steps, thus paving the way to predictive maintenance for safety qualified instrumentation. In the second case study, we propose a qualification strategy for a fiber optic-based probe which is supposed to implement a safety function in an extreme radiation environment that will expose the probe to 800 MGy over its lifetime. [ABSTRACT FROM AUTHOR]

We are using the laser induced optical barriers (LIOBs) technique to fabricate scintillator detectors with combined performance characteristics of the two standard detector types, mechanically pixelated arrays, and monolithic crystals. This is done by incorporation of so-called OBs that have a refractive index (RI) lower than that of the crystal bulk. Such barriers can redirect the scintillation light and allow for control of the light spread in the detector. Previous work has shown that the LIOB technique has the potential to achieve detectors with high-transversal and depth of interaction (DOI) resolution simultaneously in a single-side readout configuration, suitable for high-resolution positron emission tomography imaging. However, all designs studied thus far present edge effect issues similarly as in the standard detector categories. In this paper, we take advantage of the inherent flexibility of the LIOB technique and investigate alternative barrier patterns with the aim to address this problem. Light transport simulations of barrier patterns in cerium-doped lutetium yttrium orthosilicate (LYSO:Ce), with deeper barrier walls moving toward the detector edge show great promise in reducing the edge effect, however, there is a tradeoff in terms of achievable DOI information. Furthermore, fabrication and characterization of a 20-mm-thick LYSO:Ce detector with OBs forming a pattern of $1 \times 1 \times 20$ mm3 pixellike structures show that light channeling in laser-processed detectors in agreement with OBs with RI between 1.2 and 1.4 is achievable. [ABSTRACT FROM AUTHOR]

The mass production of new generations of high quality and very performant scintillating crystals requires sophisticated measurement systems and inspection tools in order to have reliable and precise data from such anisotropic materials. These measurement systems must be compatible with the industrial requirements and must be able to provide effective feedbacks aimed to the control of the crystals’ production quality. In this paper, a set of photoelasticity-based methods, solving the main limits of the presently available inspection systems, is presented. The main characteristics of such methods are the noninvasiveness, precision, and speed, which are well suited for their use in the industrial environment. This paper describes a set of measurement techniques and reports on real experimental data obtained on crystals having different cutting geometries with respect to the optic axes. The use of the proposed measurement methods, from laser conoscopy to laser sphenoscopy, along the optic axis and orthogonal to it, therefore provides a portfolio of noninvasive measurement techniques, and therefore, it is opening valuable space for the quality control of crystals in a production environment, optimizing important aspects such as the time duration of the inspection and its spatial resolution. [ABSTRACT FROM AUTHOR]

During the International Thermonuclear Experimental Reactor (ITER) reactor operation time, the plasma will give rise to high energy neutron and gamma flux, and this intense radiation field will result in serious radiation damage and activation effects on various detectors components. In this paper, neutron detector candidates for the ITER radial neutron camera (RNC), i.e., scintillator components [crystal and plastic scintillators, optical windows, and photomultipliers (PMTs)] and single-crystal diamond detectors, were investigated to establish their radiation hardness and stability under gamma irradiation. Radiation test was carried out at the Italian National Agency for New Technologies, Energy and Sustainable Economic Development Calliope plant (Casaccia R.C., Rome, Italy). The facility is a pool-type irradiation plant equipped with a 60Co source (energy = 1.25 MeV). Gamma radiation tests were performed in the dark and at room temperature for different total absorbed doses, as required for the application in ITER RNC. Scintillators, PMTs, and optical windows were irradiated up to around 100-kGy absorbed dose, while single-crystal diamond detectors up to around 5 MGy. Scintillators and optical windows transmittance measurements were performed in the UV-VIS range (300–700 nm), paying particular attention to the behavior at 390 and 420 nm (scintillating emission wavelengths). Samples were measured in the dark before and after irradiation and their performances were monitored at room temperature for some weeks in order to study the damage recovery in different conditions. For plastic scintillators, photobleaching and optical bleaching followed by thermal annealing processes in air were made to reduce the radiation damage. Quantum efficiency measurements were performed on the PMTs, and the pulse-height spectra and pulse shape capability of the scintillators were investigated by using gamma and neutron sources. The most relevant results of this paper concern the radiation damage observed in scintillators and diamond detectors. The crystalline scintillator sample showed much less radiation resistance than plastic scintillators. A strong damage to the silver deposition of the diamond contacts was observed already at 1.0 MGy, almost leading to contact destruction at 4.7 MGy. [ABSTRACT FROM AUTHOR]

A CubeSat payload (PL) was designed at CERN and at the University Space Center of Montpellier, for the measurement of radiation and its effects on electronics and single event latchup recording on SRAM devices. The PL and the data handling modules were tested at the CERN mixed-field facility, in a Low Earth Orbit representative environment. [ABSTRACT FROM AUTHOR]

In this paper, the single-event effects on a 28-nm static random access memory-based field-programmable gate array (FPGA) under CERN’s mixed-particle field are analyzed. The methodology followed for CERN electronics radiation hardness assurance and the particularities of testing an FPGA under a mixed-particle field are demonstrated. More specifically, the potential contribution of low-energy particles to the configuration memory (CRAM) and block memory (BRAM) bit upset sensitivity is investigated. By using a method of irradiating the device in different locations at CERN high-energy accelerator mixed field/facility with different particle energy spectra, it has been found that there is a significant impact of thermal neutrons, increasing the CRAM and BRAM cross section by a factor of $\times 3$. As a complement to this paper, an example application is also tested, in the context of future upgrades at the CERN accelerator complex. Results estimate that the application fails less than 10 times per year, leading to the conclusion that such devices may be used for low criticality applications along the accelerator complex. [ABSTRACT FROM AUTHOR]

The impact of exposing an optical fiber to 6-MeV electrons on the performances of optical frequency domain reflectometry (OFDR) distributed sensors is investigated. Six different types of optical fibers with different core compositions and coatings have been tested: four fibers are metal coated (copper, gold, or aluminum) for high-temperature >300 °C) operations while the two others have telecom-grade acrylate coatings for operation below 80 °C. The fiber Rayleigh signature used to perform the OFDR sensing remains almost unaffected after an electron exposure. Indeed, the measured radiation-induced temperature errors are lower than about 3 °C, close to the setup uncertainties, when the OFDR operates as a temperature sensor. [ABSTRACT FROM AUTHOR]

This paper highlights the impact of design on the single-event upset (SEU) sensitivity of D-flip-flops (DFFs) used in a readout circuit (ROIC) under heavy ions. New experimental data obtained at the University of Louvain for several designs are presented. The single-event effect (SEE) prediction tool multi-scale single event phenomena predictive platform is used to investigate the failure occurrences at the circuit level as a function of the design. In some cases, design specificities allow for increasing in the SEU robustness of the DFF. However, it appeared that cryogenic temperatures limit the impact of the design on the SEU sensitivity of DFFs. The results show a very limited impact of the temperature on the SEU occurrence, independent of the layout. These results are consistent with the experimental data presented in recent works regarding single-event transient and single-event functional interrupt. These results allow for performing irradiation tests of complementary metal–oxide–semiconductor IR detector (ROIC) at room temperature instead of cooling down the device during the SEE measurements. [ABSTRACT FROM AUTHOR]

The general reduction in the thicknesses of critical dielectric layers driven by Moore’s law scaling has led to increasingly more manageable total-ionizing-dose (TID) response over the last ~50 years. Effects of oxide, interface, and border traps in MOS gate oxides on TID response are now mostly well known for SiO2 gate dielectrics, and the leakage currents due to isolation oxides can be conservatively bounded with existing test methods. Radiation hardened and/or radiation-tolerant technologies have been developed that can survive doses that exceed 1 Mrad(SiO2). Advances in computing technology enabled by Moore’s law scaling and concomitant enhancements in computational techniques have greatly facilitated the modeling and simulation of TID effects in microelectronic devices and ICs. However, the TID response of nanoscale MOS devices with advanced gate stacks and high- ${K}$ gate dielectrics, and/or alternative materials to Si, is often more complex than for MOS devices with SiO2 gate oxides. TID challenges remain for linear bipolar technologies that exhibit enhanced low-dose-rate sensitivity and for microelectronic devices that must function at doses above ~100 Mrad(SiO2), e.g., in high luminosity accelerator environments. TID effects have also recently been observed in wide bandgap semiconductor devices (e.g., GaN/AlGaN HEMTs) with no gate oxide. [ABSTRACT FROM AUTHOR]

Using a dedicated setup, the growth and decay kinetics of the radiation-induced attenuation (RIA) have been characterized during and after steady-state 40-keV X-ray exposures of bulk (1-cm thickness) optical materials. Such materials served to design the lenses of radiation-hardened cameras of the FURHIS Project intended to withstand MGy (SiO2) dose levels associated with ITER remote handling operations. RIA is monitored in situ in the 400- to 800-nm spectral domain for glass types ranging from radiation sensitive (BK7) to radiation hardened ones: pure silica, BK7G18, K5G20, and SF6G05 from SCHOTT. In addition to the detailed characterization of these various glasses, our study highlights the systematic underestimation of the RIA measured by the usual qualification approach consisting in postirradiation RIA measurements after dose steps. The error due to this underestimation is shown to strongly depend on the glass type, very large for the BK7G18 glass. This material is associated with high transient RIA, its loss levels exceed the ones of its nonrad-hard counterpart (BK7) at low dose levels. For the development of MGy radiation-hardened systems using these glasses, a vulnerability study of the in situ response of glass lenses appears mandatory. By improving our knowledge on the origin of these transient losses, appropriate hardening techniques to maintain the camera photometry budget will be tested in the future. [ABSTRACT FROM AUTHOR]

The voids-fiber Bragg gratings (FBGs) are manufactured point by point by focalizing an infrared femtosecond laser in a small fraction of the core and creating a microscopic void. This makes these gratings very resistant and stable to high temperatures. However, until today, only very few tests under radiation have been performed on these FBGs. A complete study on the radiation response of this grating technology under X-rays is here presented, highlighting the dependence of its radiation response on dose, dose rate, irradiation temperature, and preirradiation treatment. [ABSTRACT FROM AUTHOR]

An experimental investigation of Ni-ion (energy 3.6 MeV/nucleon) and $\gamma $ -ray irradiation effects on three different types of silica-based glasses: N-BK7 and two pure-silica (Herasil and Suprasil) samples has been conducted. Confocal micro-Raman (CMR) and confocal microluminescence experiments (CML) allowed investigating the glass structural and emission modifications caused by both radiation types. Raman data recorded in the ion-irradiated samples provide evidence for increased concentration of the three membered rings in the pure-silica samples and of the boron nonbridging oxygens in BK7 in the first $15~\mu \text{m}$ from the surface. The principal CML results, obtained under 325-nm excitation, concern the dose dependences of green light emissions detected at ~530 nm in pure silica and 550 nm in BK7. The related emitting centers are located in the first micrometer under the surface exposed to Ni ions. When exciting these samples at 633 nm, the signature of the Nonbridging Oxygen Hole Center (NBOHC) is detected in the irradiated silica materials. NBOHCs feature the expected dose dependences in the $\gamma $ -ray irradiated samples. Considering the Ni-irradiated materials, their CML profiles have similar shape, suggesting that their concentration is almost constant up to 15- $\mu \text{m}$ depth and then decreases quickly. The CML spectra of the BK7 pristine sample are dominated by a 780-nm emission, whereas after irradiation, a signal peaking at 750 nm becomes preponderant. Such activity follows a sublinear (Dose0.5) growth under $\gamma $ rays; this result if confirmed at lower doses suggests a generation from matrix site rather than a precursor site. The CML profile in the Ni-irradiated specimen suggests that most of the radiation-induced defects are located in the first $15~\mu \text{m}$ under the surface. The CMR and CML data of the Ni-irradiated materials qualitatively agree with the energy loss simulation performed using the SRIM software. [ABSTRACT FROM AUTHOR]