Radiation Test Results Research Articles

Proton irradiation of FPGA-embedded hadron fluence sensors

Hadron fluence monitors based on static random access memories (SRAMs) are in use at particle accelerators for the protection of electronics and at proton-therapy facilities for measuring secondary neutrons. One shortcoming of current solutions is that they necessitate SRAMs to detect radiation-induced single event upsets and require additional components to transfer the counts from the radiation area. This approach limits the practicality of the sensors due to their power requirements, increased board complexity, larger physical footprint and reduced total ionizing dose tolerance. In this work, we present proton irradiation test results of a novel proton and neutron fluence sensor we designed. The sensor is fully embedded in a SRAM-based field programmable gate array (FPGA) solving the abovementioned limitations of the state of the art. The FPGA configuration SRAM is used as a sensitive element, while the Joint Test Action Group interface is leveraged as a read out circuitry. We irradiated six sensor units by means of a variable-energy proton beam at the Trento Institute for Fundamental Physics and Applications (TIFPA, Trento, Italy). We discuss our results in terms of proton to upset cross section as a function of the proton energy in the range from 70 to 228 MeV, also parameterized with respect to the power supply voltage. We evaluate the variability of the cross section in the set of irradiated samples. Moreover, we show how we used the device to image the proton beam and measure beam profiles for aligning the configuration RAM and beam centers. We also suggest alternate reading modes to measure the fluence on the device by measuring the drawn current, rather than counting upsets.

Experimental Investigation of a System of Two Vacuum Solar Receivers for the Continuous Reduction of Ceria Particles

A solar receiver for the continuous reduction of redox particles under vacuum conditions has been developed previously as part of a system to produce hydrogen from solar energy. Here, we report about a joint effort of Sandia and DLR to improve the receivers design and to demonstrate a system of two receivers with different vacuum pressures at DLR’s solar simulator Synlight. We focus on the design and experimental investigation of three components: the novel beam down mirror, the novel secondary concentrator and the improved version of the particle conveying plate in the receiver. Irradiation test results and heat transfer analyses of the beam-down mirror and the secondary concentrator are being presented. The motion of the conveyor plate was improved by a MATLAB model, which predicts the transport speed of the particles on the conveyor.

A science‐based mixed oxide property model for developing advanced oxide nuclear fuels

AbstractHerein, a science‐based uranium and plutonium mixed oxide (MOX) property model is derived for determining the properties of MOX fuel and analyzing their performance as functions of Pu content, minor‐actinide content, oxygen‐to‐metal ratio, and temperature. The property model is constructed by evaluating the effect of phonons and electronic defects on the heat capacity and thermal conductivity of MOX fuels. The effect of phonons was evaluated based on experimental datasets related to lattice parameters, thermal expansion, and sound speeds. Moreover, the effect of electronic defects was determined by analyzing oxygen‐potential data based on defect chemistry. Furthermore, the model evaluated the effect of the Bredig transition on the thermal properties of MOX fuel by analyzing the irradiation test results. The derived property model is applied to the performance code to analyze fast reactor fuel pins.

Investigation of edge computing hardware architectures processing tiny machine learning under neutron-induced radiation effects

This article investigates 14-MeV neutron radiation soft-error effects on two contrasting hardware architectures for edge computing systems, one based on an 8-bit processor and another on a 64-bit processor, both processing three frequently used types of tiny machine learning (ML) algorithms. Experimental results of 14-MeV neutron radiation tests in the different case-study ML algorithms running on the 64-bit processor show that the artificial neural network version using floating point failed more than the other versions, although most failure situations caused no misclassification in the ML inference. Furthermore, considering tiny ML applications demanding the investigated 8-bit and 64-bit computing systems for the same amount of ML inferences, the overall results suggest a preliminary trend that both case-study systems would have similar tolerance to 14-MeV neutron radiation soft errors.

Estimation of radionuclides leaching characteristics in different sized geopolymer waste forms with simulated spent ion-exchange resin

This study presents a method to solidify spent ion-exchange resin (IER) in a metakaolin-based geopolymer and shows results of mechanical strength, immersion, leaching, irradiation, and thermal cycling tests for waste acceptance criteria (WAC) to repository. The geopolymer waste form with 20 wt% of simulated spent IER met the WAC in South Korea (ROK), and the leaching tests of various sized-waste forms up to 15.0 × 30.0 cm and waste loadings up to 20 wt% for 1–5 d and 1–90 d achieved a leachability index, Li > 6. In a leaching test for 5 d, the cumulative fraction leached (CFL) for Cs, which leached the most, was linearly correlated with the square root of leaching time for all waste forms, and Li increased as the size of the waste form increased. The CFL was also correlated with elapsed time in the 90 d leaching test. The correlations among CFL, time, and volume-to-surface area ratio of waste forms used to estimate the Li of Cs of a 200-L sized geopolymer with 15 wt% IER showed the Li values as 14.73 (5 d) and 17.71 (90 d), respectively, indicating that the large-sized geopolymer waste form met the WAC.

Energy aggregation properties of TiO2-silica composite aerogel under ultra-high-energy (7 kW·cm-2) continuous-wave laser irradiation

TiO2, a light-shielding agent for silica aerogels, is widely used in optical limiting and photocatalysis, but its application in high-energy lasers is extremely limited. We added TiO2 to silica aerogel in three different ways to get the best resistance to high energy laser. Through microstructure analysis and high energy laser irradiation test results, it is concluded that direct deposition of TiO2 nanoparticles can achieve the best laser resistance synergistic effect with silica aerogel. A thermal barrier temperature difference of 1275 °C was generated with a material thickness of 7.5 mm. Comparing the microscopic pore structure before and after high-energy laser irradiation, it was observed that the phase transition destruction of the TiO2–silica composite aerogel was completely different from that of pure silica aerogel. The TiO2–silica composite aerogel showed no signs of breakdown within 2 min of continuous-wave (CW) laser irradiation with power of 7 kW·cm-2. By changing the amount of TiO2 added, we also obtained the general trend of this synergistic effect, extended the mathematical model “maximum energy transfer radius (METR)”, and advanced the application of this material in the field of high energy laser protection.

Self-powered Through-wall communication for dry cask storage monitoring

Many nuclear facilities, such as spent fuel storage dry casks and nuclear reactor pressure vessels, are entirely sealed by metal layers to prevent harmful radiation. For safety and security operations, the temperature, pressure, radiation, and humidity inside the vessel needs to be closely monitored. However, no practical technology is currently available to realize the through-wall data communication and monitoring for these vessels due to the inside harsh environment of high temperature and nuclear radiation. In this paper, an innovative self-powered wireless through-wall data communication system for the nuclear environment is presented, which demonstrates a successful solution to such challenges. The presented system is composed of four modules, i.e., energy harvester with power management circuits, ultrasound wireless communication using high-temperature piezoelectric transducers, electronic circuits for sensing and data transmission, and radiation shielding for electronics. Constitutive functions of each module were firstly designed and followed by the system integration. Experiments were conducted subsequently to validate the designed functions and evaluate the performance of the integrated system. Results showed that the average power of over 40 mW was harvested from the thermal flow inside the nuclear spent fuel canisters which could provide enough energy to operate the sensing and data communication systems. The gamma radiation test results showed that the thermoelectric energy harvester and ultrasound transceivers can withstand radiation dosing over 100 Mrad. Furthermore, temperature shock tests demonstrated that the entire system including the shielded electronics can survive and maintain their functionalities at temperatures as high as 195℃. Under the in-lab mocked-up high temperature conditions and radiation shielding, the proposed system is foreseen to survive and operate stably for fifty years inside a nuclear spent fuel canister, and send the frequency modulated data out of the canister for 3 s in every 10 min.

A Soft-Error Hardened by Design Microprocessor Implemented on Bulk 12-nm FinFET CMOS

We describe the porting of a soft-error (SE) hardened microprocessor to a modern 12-nm bulk CMOS finFET fabrication process and radiation testing results. The microprocessor includes latch-based cache and main register file (RF) arrays, with compact dual-patterned layouts. It is protected by dual modular redundancy (DMR) in the speculative pipeline, RF, and caches. Self-correcting triple modular redundant (TMR) flip-flops provide fine-grain protection in the TMR circuits that hold key architectural state. The DMR circuits are protected by checking circuits at the caches, RF, and crossovers to the TMR state. In the event of a DMR mismatch, an SE exception is taken, and the machine state is repaired via software. This approach also allows the detailed machine state reporting to elucidate the SE root cause circuits and cross sections. Broad beam radiation testing shows that it responds correctly to detected SEs. The by-circuit cross sections of the various circuits are reported for both heavy ions and protons.

Assessment of Tiny Machine-Learning Computing Systems Under Neutron-Induced Radiation Effects

This article compares and assesses the effectiveness of three prominent machine learning (ML) models for tiny ML computing systems in tolerating neutron-induced soft errors. Results of 14-MeV and thermal neutron radiation tests suggest that the three case-study ML algorithms implemented—without any mitigation technique integrated—retain a certain intrinsic level of effectiveness in tolerating neutron effects, although all of them have been functionally interrupted on some occasions, requiring hardware resets. Notably, the implemented case-study ML algorithm “random forest” has performed no misclassification during the different radiation testing campaigns.

Characterization of the Total Charge and Time Duration for Single-Event Transient Voltage Pulses in a 65-nm CMOS Technology

This article presents the circuits and heavy-ion irradiation test results of a single-event transient (SET) measurement chip in a 65-nm complementary metal–oxide–semiconductor (CMOS) technology. The measurements contain two parts: total SET ionization charge and SET pulse duration. Transistors with different types and dimensions were implemented as victim devices to evaluate how transistor parameters impact the SET effects. Additionally, SET variation from different supply voltages was also investigated. The test chip has been tested under a heavy-ion beam with an effective linear energy transfer (LET) from 20.4 to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$88.35~\text {MeV}\cdot \text {cm}^{2}$ </tex-math></inline-formula> /mg using a 0°–45° incidence angle.

Three-dimensional simulation of total ionizing dose effect on SiGe heterojunction bipolor transistor

The damage mechanism of the total ionizing dose (TID) effect of SiGe heterojunction bipolor transistar (SiGe HBT) is explored by using three-dimensional simulation of semiconductor device (TCAD).In the simulation, the trapped charge defects are introduced into different locations of oxidationin SiGe HBT to simulate the TID effect. Then the degradation characteristics of the forward Gummel characteristic and the reverse Gummel characteristic of the device are analyzed, and the TID damage law of SiGe HBT is obtained. Finally, the simulation results are compared with the &lt;sup&gt;60&lt;/sup&gt;Co γ irradiation test results, showing that the trapped charges introduced by TID irradiation in SiGe HBT device mainly affect the Si/SiO&lt;sub&gt;2&lt;/sub&gt; interface near the p-n junction, resulting in the change in the depletion region of the p-n junction and the increase of carrier recombination. Eventually, the base current increases and the gain decreases. The trapped charges generated in the EB spacer oxide layer mainly affect the forward Gummel characteristics, and the trapped charges in the LOCOS isolation oxide layer are the main factor causing the reverse Gummel characteristics to degrade. The experimental results on &lt;sup&gt;60&lt;/sup&gt;Co γ irradiation under different biases are consistent with those from the total dose effect damage law of SiGe HBT obtained by numerical simulation analysis.

Evaluation of Ionizing Radiation Effects on Device Modules Used in Wireless-Based Monitoring Systems

To increase the reliability of wireless-based monitoring systems under ionizing radiation environments, multiple diversified commercial off-the-shelf (COTS) modules have been used to achieve radiation tolerance. This paper presents experimental results of radiation tests on key modules in wireless-based monitoring systems, which include analog signal processing circuits, analog-to-digital converter (ADC) modules, microcontroller modules, and wireless transmission modules. In total, 12 modules have been evaluated, (i.e. 3 analog modules, 3 ADCs, 3 microcontrollers, and 3 wireless transmission modules). The radiation tests are conducted using the gamma radiator at The Ohio State University Nuclear Reactor Lab (OSU-NRL). The performance parameters of these 12 modules are investigated under high dose rate (20 krad(Si)/h). Experimental results have shown that the tested modules perform satisfactorily with little sign of degradation until the total dose levels reach the tolerable limits for these modules. Experimental results support the fact that, by using diversified COTS components, one may be able to achieve equivalent performance as those built by using radiation-hardened components, but with a considerable cost-saving. Furthermore, the tests also show that digital modules, particularly, with higher speed processors (i.e. microcontrollers) may be more susceptible to radiation than other types of modules. Therefore, additional shielding should be used to protect them.

Radiation induced absorption of hydrogen-loaded pure silica optical fibers with carbon coating for ITER diagnostics

We present results of gamma irradiation tests of 200 μm pure silica core optical fibers with a low and high-OH concentration, with and without hydrogen loading. All the fibers were manufactured by a candidate supplier of the fiber bundles for optical plasma diagnostics in ITER. The hydrogen-loaded fibers were stored for a one year before the irradiation start. The fibers were exposed at two Co-60 gamma facilities using dose-rates of 15 and 194 mGy/s up to 15 and 70 kGy absorbed doses, respectively. The optical transmission losses of the fibers were measured in-situ in the spectral range of 450–900 nm. The results are interpreted on the basis of available data on radiation defects in silica core fibers. It is demonstrated that hydrogen loading provides a radiation hardness improvement, which allows to satisfy the ITER requirements.

Large Area 23%-Efficient Monolithic Perovskite/Homo-Junction-Silicon Tandem Solar Cell with Enhanced UV Stability Using Down-Shifting Material

UV induced degradation is a big issue for perovskite-based solar cells. Parasitic ultraviolet (UV) absorption by the “sun-facing” carrier transport layer in a perovskite cell also hinders the electrical performance when the cell is a top cell for a Si-based tandem. In this work, we tackle these issues by applying textured polydimethylsiloxane (PDMS) films that incorporate a down-shifting material (Ba,Sr)2SiO4:Eu2+ micron phosphor on the front of monolithic perovskite/silicon tandem cells. This film serves multiple purposes optically: antireflective control for the top cell, light trapping in the Si cell as well as absorbing UV and re-emitting green light with high quantum yield. The morphology of the phosphor, optical properties of the phosphor as well as the phosphor incorporated film, water, moisture, UV stability as well as the mechanical flexibility of the anti-reflective down-shifting film were investigated. The effect of phosphor concentration in the antireflective PDMS film on tandem device efficiencies was also studied. This down-shifting antireflective film is suitable for large areas. When applied onto a 4 cm2 monolithic perovskite/silicon tandem solar cell, the power conversion efficiency was improved from 20.1% (baseline device without any anti-reflective film) to 22.3% (device with anti-reflective film but without the phosphors) and to 23.1% (device with down-shifting and antireflective film). The steady-state efficiency of 23.0% and a high FF of 81% achieved by the champion device are the highest values to date for a monolithic perovskite/Si tandem that uses homo-junction-silicon bottom cell. Moreover, results of continuous UV irradiation test show that this composite down-shifting antireflection film significantly enhances the UV stability for the tandem device. The demonstrated efficiency and stability enhancement achieved by such elegant approach paves a way for improving the commercial viability of perovskite/silicon tandems and other perovskite photovoltaic applications.

Evaluating the Radiation Effects on the Characteristics of the Silicon Avalanche Photodiode with Protons

Silicon avalanche photodiode (Si APD) plays important roles in high sensitive optical detecting applications, such as remote sensing, radiation detection and optical communication etc. However, in the space, the Si APD would unavoidably suffer radiation damage, which would degrade the Si APD performance, like dark current, responsivity and gain etc. Here, we report the results of Si APD radiation tests with protons to evaluate their radiation hardness properties and suitability for space missions. With this motivation, samples have been radiated using 50 MeV protons with maximum does 1E12 p(proton)/cm2 The test results show that the Si APD dark current increment is negligible when the radiation dose is below 1E11 p/cm2, ∼10 nA, satisfying most nanowatt level detecting applications. As the radiation dose further increases to 1E12 p/cm2, the Si APD breakdown voltage has a measureable decrement, which subsequently increases the dark current and gain. And through over two years’ in-orbit test, the Si APD dark current keeps below 1 nA, while the responsively is ∼4.9 A/W.

Qualification and Calibration of Single-Mode Phosphosilicate Optical Fiber for Dosimetry at CERN

We report the results of several complementary radiation tests to qualify and calibrate a highly radiation sensitive Single-Mode (SM) Optical Fiber (OF) for distributed dosimetry application at CERN. The Radiation Induced Attenuation (RIA) is the physical phenomenon used to evaluate the Total Ionizing Dose (TID) received by the OF sensor. The radiation response tests comprise online RIA in the Near InfraRed (NIR) domain under 60Co γ-rays, X-rays and proton irradiations, as well as post mortem Optical Attenuation (OA) measurement to evaluate long term fading effects of the RIA. In this paper, we focus on the effect of successive irradiations, dose rate dependence and effects related to the change of the irradiation temperature up to 45 °C. On the basis of our investigation, we conclude that the studied OF is a suitable TID sensor and that it is well adapted for distributed OF radiation dose sensing. It is fully compatible with commercially available SM Optical Time Domain Reflectometers, with some noticeable advantages with respect to previously developed systems based on multimode OFs. Finally, the OF we investigated has been selected for the distributed monitoring of low radiation dose levels at CERN in the injector chain (Proton Synchrotron Booster, Proton Synchrotron, Super Proton Synchrotron) and parts of the Large Hadron Collider (LHC).

Characterizing SRAM and FF soft error rates with measurement and simulation

Soft error originating from cosmic ray is a serious concern for reliability demanding applications, such as autonomous driving, supercomputer, and public transportation system. Also, as the number of electronic devices increases, consumer electronics may require higher reliability than ever. On the other hand, device miniaturization and lower voltage operation degrade the immunity of SRAM and flip-flops in VLSI, and then soft error countermeasures will be demanded in more and more products. This paper characterizes and discusses soft error rates of SRAM and flip-flops in the terrestrial environment. Measured soft error rates of bulk and FDSOI SRAMs are presented. Also, the multiplicity and mechanism of multiple cell upsets (MCUs), which can spoil error correction code (ECC), are discussed. Flip-flops are also sensitive to radiation, but its protection is not well established since ECC cannot be applied. This paper reviews redundant FFs that are developed aiming at higher radiation immunity and demonstrates the resilience improvement with irradiation test results. Also, the importance of layout design is pointed out with a comparative study. Simulation, on the other hand, is a key technology to understand the soft error mechanism and guide radiation aware design for higher reliability. This paper outlines a physics-based multi-scale Monte Carlo simulation framework tailored for soft error simulation. The simulation flow and the model construction are explained, and some important implications are derived from the simulation results that assume 65-nm to 25-nm SRAMs. Finally, this article touches on future trends regarding device structure and overlooked secondary cosmic rays. The advantage and unique features of FinFET recently reported in literature are introduced. Also, muon-induced soft error is discussed focusing on the difference between positive and negative muons.

«On-line» neutron fluence registration by silicon bipolar transistor

An efficient practical method of bipolar transistor application for neutron fluence registration is presented. The method is focused on the neutron fluences damage effect correlation for various sources to reference source. The bipolar transistor connection diagram and an example of device realization based on STM32 microcontroller are described. STM32 is used for providing test signals and parameter registration used for gain factor calculation of the bipolar transistors monitor (BTM). The proposed approach allows to consider the features of BTM that is pre-irradiated at reference source and their application as the neutron fluence monitors. These connection diagram and constructive solutions provide “on-line” neutron fluence registration for different sources in terms of the reference source as required for the verification of radiation test results.

Study of the Impact of the LHC Radiation Environments on the Synergistic Displacement Damage and Ionizing Dose Effect on Electronic Components

Bipolar-based components can exhibit a higher (or lower) degradation when exposed to both total ionizing dose (TID) and displacement damage (DD) effects simultaneously than the sum of the two separated effects. This paper investigates the implications of this synergistic effect on the radiation qualification process of large hadron collider’s (LHC’s) electronic equipment. More specifically, the impact of the wide range of DD/TID rate ratios of the LHC’s areas on the synergistic degradation rates is investigated. An analysis of the ratios of a crucial part of the accelerator is performed. A demonstration of the ability of the CHARM mixed-field facility of CERN to perform radiation tests in representative LHC’s ratios is also presented as well as radiation test results of a bipolar integrated circuit exposed to these different ratios are presented. Finally, the impact of this effect on the CERN radiation hardness assurance process is discussed and a simple method is proposed to qualify component against such effects.

Radiation tests of Hamamatsu multi-pixel photon counters

Results of radiation tests of Hamamatsu 2.0 × 2.0 mm2 through-silicon-via (S13360-2050VE) multi-pixel photon counters, or MPPCs, are presented (Hamamatsu, 0000). Distinct sets of eight MPPCs were exposed to four different 1 MeV neutron equivalent doses of 200 MeV protons. Measurements of the breakdown voltage, gain and noise rates at different bias overvoltages, photoelectron thresholds, and LED illumination levels were taken before and after irradiation. No significant deterioration in performance was observed for breakdown voltage, gain, and response. Noise rates increased significantly with irradiation. These studies were undertaken in the context of MPPC requirements for the Cosmic Ray Veto detector of the Mu2e experiment at the Fermi National Accelerator Laboratory.