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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Relationship between the Optical Damage Resistance and Radiation Hardness and the Influence of Threshold Effects on the Radiation Hardness of ZnO-Doped LiNbO{sub 3} Crystals

The radiation hardness and optical characteristics of beta-and gamma-irradiated LiNbO{sub 3}〈ZnO〉 crystals have been studied in a wide range of doping levels: ~0.04–5.9 mol % ZnO. The optical absorption (transmission) of the beta-and gamma-irradiated LiNbO{sub 3}〈ZnO〉 crystals has been evaluated as a function of the type and dose of radiation and dopant concentration. The optical damage resistance and radiation hardness of the crystals have been shown to be interrelated and depend on threshold effects in the LiNbO{sub 3}〈ZnO〉 crystals.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2022

Radiation hard gallium oxide scintillators for high count rate radiation detection

Despite decades of materials research, the availability of appropriate crystalline radiation-hard scintillators with ultrafast decay times (~10ns) and high light yields (>2000 ph/MeV) are still limited. In this study, we demonstrate the potential of gallium oxide (β-Ga 2 O 3 ) based scintillators for high count rate applications. The low-cost rugged β-Ga 2 O 3 scintillators were grown using the optical float zone (FZ) technique. Several dopants and growth atmospheres were used to demonstrate the balance between ultrafast primary decay time and the light yield of the scintillators. Light yields as high as 6446 ± 716 ph/MeV were obtained with 18.3 ns decay time for 662 keV gamma rays. Decay times as fast as 12ns were obtained with a 3212 ± 357 ph/MeV light yield. An excellent 662 keV gamma energy resolution of 7% was obtained using the β-Ga 2 O 3 :Ce crystals. Even with these excellent scintillation properties, the gamma radiation hardness of β-Ga 2 O 3 crystals was better than the leading radiation-hard lead tungstate (PbWO 4 ) crystals. Twenty-six scintillators fabricated from the grown β-Ga 2 O 3 crystals were tested for radiation hardness with a 60 Co gamma irradiation rate of 14 krad/h with a total radiation dose of 2 Mrad. The scintillation properties of these crystals remained unaffected. To date, no other scintillator has demonstrated such high radiation resistance. Furthermore, these FZ-grown low-cost, non-hygroscopic, and high-density β-Ga 2 O 3 scintillators can replace the existing scintillators in many applications ranging from nuclear and high energy physics experiments to nuclear security.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2012

Radiation Hard AlGaN Detectors and Imager

Radiation hardness of AlGaN photodiodes was tested using a 65 MeV proton beam with a total proton fluence of 3x10{sup 12} protons/cm{sup 2}. AlGaN Deep UV Photodiode have extremely high radiation hardness. These new devices have mission critical applications in high energy density physics (HEDP) and space explorations. These new devices satisfy radiation hardness requirements by NIF. NSTec is developing next generation AlGaN optoelectronics and imagers.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2011

Radiation hardness of the storage phosphor europium doped potassium chloride for radiation therapy dosimetry

Purpose: An important property of a reusable dosimeter is its radiation hardness, that is, its ability to retain its dosimetric merits after irradiation. The radiation hardness of europium doped potassium chloride (KCl:Eu{sup 2+}), a storage phosphor material recently proposed for radiation therapy dosimetry, is examined in this study. Methods: Pellet-style KCl:Eu{sup 2+} dosimeters, 6 mm in diameter, and 1 mm thick, were fabricated in-house for this study. The pellets were exposed by a 6 MV photon beam or in a high dose rate {sup 137}Cs irradiator. Macroscopic properties, such as radiation sensitivity, dose response linearity, and signal stability, were studied with a laboratory photostimulated luminescence (PSL) readout system. Since phosphor performance is related to the state of the storage centers and the activator, Eu{sup 2+}, in the host lattice, spectroscopic and temporal measurements were carried out in order to explore radiation-induced changes at the microscopic level. Results: KCl:Eu{sup 2+} dosimeters retained approximately 90% of their initial signal strength after a 5000 Gy dose history. Dose response was initially supralinear over the dose range of 100-700 cGy but became linear after 60 Gy. Linearity did not change significantly in the 0-5000 Gy dose history spanned in this study. Annealing high dose history chips resulted in a return of supralinearity and a recovery of sensitivity. There were no significant changes in the PSL stimulation spectra, PSL emission spectra, photoluminescence spectra, or luminescence lifetime, indicating that the PSL signal process remains intact after irradiation but at a reduced efficiency due to reparable radiation-induced perturbations in the crystal lattice. Conclusions: Systematic studies of KCl:Eu{sup 2+} material are important for understanding how the material can be optimized for radiation therapy dosimetry purposes. The data presented here indicate that KCl:Eu{sup 2+} exhibits strong radiation hardness and lends support for further investigations of this novel material.

36 MATERIALS SCIENCE↗
DOE OSTI2011

On the problem of the radiation hardness of SiC nuclear radiation detectors at high working temperatures

Owing to the radiation-induced pronounced conductivity compensation in silicon carbide, carrier localization (trapping) prevails over recombination in capture of nonequilibrium carriers. This makes it possible, by raising the temperature, to reduce the time of carrier retention by a trapping center to values shorter than the duration of signal shaping by electronic circuits. For structural defects created by 6.5-MeV protons, the temperature excluding degradation of the detector signal via carrier localization is estimated. The values of the appearing generation current the noise of which can restrict the operation of a detector in the spectrometric mode are determined.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Radiation hardness characterization of LKH-5 scintillating glass

Radiation hardness is an important property to examine in scintillators to help determine their expected lifetime in application cases where significant radiation dose is expected. Industrial imaging systems using 9 MV linear accelerators for x-ray radiography are one such application where significant radiation doses are expected to the scintillators used. Cadmium tungstate scintillators (CWO) and Thallium doped Cesium Iodide scintillators (CsI(Tl)) are used in some high energy cargo x-ray radiography systems. However, CWO has a high manufacturing cost for adequately uniform crystals and CsI(Tl) does not have sufficient radiation hardness. LKH-5 glass is being investigated as a potential low cost replacement for CWO and CsI(Tl). In this experiment 36 samples of a terbium doped silicate glass called LKH-5 were irradiated at doses up to 5 MRad using a 9 MV linear accelerator, and the change in their transmission properties was observed. Additionally, the glass was discovered to be a radiation hard glass due to the relatively small change in the transmission of the glass: less than 3% per cm at its emission peak of 550 nm and 5 MRad. This is similar to CWO which has a reported reduction in transmitted light of 2% per cm at 5 MRad and the emission peak of 475 nm and better than CsI(Tl) which is reported to have a reduction in transmitted light of 5% per cm at the emission peak of 550 nm and 4.2 MRad dose. Furthermore, an annealing procedure is described that returned the transmission of the glass to pre-irradiation values.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2021

Neutron radiation hardness of aluminum gallium nitride UV LEDs at various wavelengths

Radiation hard diagnostics are critical to the success of nuclear fusion at National Ignition Facility, Z, ITER, and prolonged space explorations. We have first demonstrated the exceptional proton radiation hardness of initial GaN devices and qualified their space flight and deployment for missions such as the Laser Interferometer Space Antenna and International Space Station. We have further conducted neutron radiation hardness experiments at Los Alamos Neutron Science Center by opening a new high fluence beam station. During 2014–2016, we irradiated multiple Aluminum Gallium Nitride (AlGaN) LEDs with a maximum fluence of 2.4 × 1013 neutrons/cm2 in 3 years and generated 54 161 current–voltage (I–V) scan traces. Our data processing program analyzes each and all I–V traces. In addition, we retrieved local temperature records to analyze and remove temperature effects in the outdoor environment. The I–V curve families of AlGaN UV LEDs with emitting wavelengths of 265, 275, and 310 nm were compared. The I–V curves of 265 nm AlGaN UV LEDs have the smallest deviations from the average value, while the I–V curves for 310 nm AlGaN LEDs showed the largest deviations from the average value. We have reached another important recommendation for the optimal use of multiple AlGaN optoelectronic devices or imaging arrays for inertially confined fusion diagnostics: Shorter wavelength devices at 265 nm exhibit more consistent radiation hardness performance than the 310 nm devices. Higher aluminum content LEDs or AlxGa1–xN devices with higher mole fraction x for generating shorter wavelengths have better radiation hardness for fusion diagnostics.

Sun, K. -X. (ORCID:0000000224659235)↗
DOE OSTI2024

Gallium oxide semiconductor-based large volume ultrafast radiation hard spectroscopic scintillators

We report on the development of the first-ever inorganic radiation-hard moisture-insensitive large volume spectroscopic semiconductor-based scintillator with less than 2 ns decay time and light yields as high as 8000 ph/MeV. Despite extensive research into scintillator materials, the quest for an ideal scintillator combining ultrafast decay times (akin to BaF 2 and Yb-doped scintillators such as Lu 2 O 3 :Yb), high light yields (exceeding 2000 photons per MeV), spectroscopic capabilities, and exceptional radiation hardness remain unfulfilled. In this study, we demonstrate and report for the first time the viability of large-volume (up to 20 mm thickness) gallium oxide (β-Ga 2 O 3 ) semiconductor-based scintillators for applications requiring these properties. These β-Ga 2 O 3 scintillators were grown using the fast turnaround (~2 days) crucible-free optical float zone (FZ) technique. The high light yield and ultrafast decay time of these high-purity n-type semiconductors with free carrier concentration of 6 × 10 17 cm –3 are attributed to native defects, specifically oxygen vacancies (V O ) and gallium–oxygen vacancy pairs (V Ga –V O ), generated during optimized FZ growth. The ultrafast decay, along with high light yield, enables excellent timing resolution and high count rate detection for applications like time-of-flight positron emission tomography, physics experiments, and nuclear safety. The radiation hardness of these devices has been documented in a separate publication.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2018

Gallium nitride (GaN) devices as a platform technology for radiation hard inertial confinement fusion diagnostics

Inertial Confinement Fusion (ICF) is undergoing more detailed research to increase neutron yield and will require high resolution imaging near the target. Neutron damage to diagnostics remains a serious issue in understanding and achieving ICF. We have demonstrated that Gallium Nitride (GaN) optoelectronic devices have exceptional neutron radiation hardness, by systematic testing of neutron radiation effects in GaN devices and materials with elevated neutron fluence levels and a broad neutron energy spectrum. During the 2013-2017 run cycles at Los Alamos Neutron Science Center (LANSCE), we irradiated various GaN materials and devices with fast and thermal plus resonance neutrons at several beamlines. This work presents a radiation hardness study for Aluminum Gallium Nitride and Gallium Nitride (AlGaN/GaN) deep UV LEDs irradiated at the LANSCE 4FP60R beamline. The fluence level was up to 2.4 × 10 13 neutrons/cm 2 for neutrons with energies greater than 0.1 MeV. The device performance was monitored in real time. After three years of irradiation studies, we found that the GaN devices maintained operation in the forward active region. The current and voltage relation (I-V curves) varied insignificantly in the linear region. Finally, our results demonstrate the radiation hardness needed for laser fusion diagnostics at least up to 10 17 neutron yield per shot, if the diagnostics is placed 1 m away from the target, where the neutron fluence per shot is approximately 8 × 10 11 n/cm 2 . The GaN devices can operate for multiple shots.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2022

Radiation hard Ga 2 O 3 detectors for high energy physics

In this project, we explore the use of ultra-wide bandgap Ga 2 O 3 materials for fabricating next-generation radiation hard solid-state detectors for high energy physics (HEP) applications. As an emerging semiconductor, Ga 2 O 3 has ultra-wide bandgap (4.5-4.9 eV), high breakdown electric field (8 MV/cm) and much lower production cost compared with radiation hard diamond detectors, all of which make Ga 2 O 3 a great candidate material working in harsh radiation environment of future HEP experiments. The recent breakthrough of growth technologies of Ga 2 O 3 significantly improves the availability of large area single crystalline Ga 2 O 3 . We focus on an early proof-of-principle demonstration of Ga 2 O 3 detectors and conduct comprehensive material and detector characterization to evaluate the potential of the emerging Ga 2 O 3 as a new radiation-hard detector material. Our endeavors directly support the instrumentation development and update need of HEP experiments and fits very well into the DOE HEP “Detector R&D” research subprogram.

36 MATERIALS SCIENCE↗
DOE OSTI2011

AlGaN UV LED and Photodiodes Radiation Hardness and Space Qualifications and Their Applications in Space Science and High Energy Density Physics

This presentation provides an overview of robust, radiation hard AlGaN optoelectronic devices and their applications in space exploration & high energy density physics. Particularly, deep UV LED and deep UV photodiodes are discussed with regard to their applications, radiation hardness and space qualification. AC charge management of UV LED satellite payload instruments, which were to be launched in late 2012, is covered.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2015

Radiation hardness assessment of the charge-integrating hybrid pixel detector JUNGFRAU 1.0 for photon science

JUNGFRAU (adJUstiNg Gain detector FoR the Aramis User station) is a two-dimensional hybrid pixel detector for photon science applications in free electron lasers, particularly SwissFEL, and synchrotron light sources. JUNGFRAU is an automatic gain switching, charge-integrating detector which covers a dynamic range of more than 10{sup 4} photons of an energy of 12 keV with a good linearity, uniformity of response, and spatial resolving power. The JUNGFRAU 1.0 application-specific integrated circuit (ASIC) features a 256 × 256 pixel matrix of 75 × 75 μm{sup 2} pixels and is bump-bonded to a 320 μm thick Si sensor. Modules of 2 × 4 chips cover an area of about 4 × 8 cm{sup 2}. Readout rates in excess of 2 kHz enable linear count rate capabilities of 20 MHz (at 12 keV) and 50 MHz (at 5 keV). The tolerance of JUNGFRAU to radiation is a key issue to guarantee several years of operation at free electron lasers and synchrotrons. The radiation hardness of JUNGFRAU 1.0 is tested with synchrotron radiation up to 10 MGy of delivered dose. The effect of radiation-induced changes on the noise, baseline, gain, and gain switching is evaluated post-irradiation for both the ASIC and the hybridized assembly. The bare JUNGFRAU 1.0 chip can withstand doses as high as 10 MGy with minor changes to its noise and a reduction in the preamplifier gain. The hybridized assembly, in particular the sensor, is affected by the photon irradiation which mainly shows as an increase in the leakage current. Self-healing of the system is investigated during a period of 11 weeks after the delivery of the radiation dose. Annealing radiation-induced changes by bake-out at 100 °C is investigated. It is concluded that the JUNGFRAU 1.0 pixel is sufficiently radiation-hard for its envisioned applications at SwissFEL and synchrotron beam lines.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2022

RADiCAL—Precision Timing, Ultracompact, Radiation-Hard Electromagnetic Calorimetry

To address the challenges of providing high-performance calorimetry in future hadron collider experiments under conditions of high luminosity and high radiation (FCC-hh environments), we conducted R&D on advanced calorimetry techniques suitable for such operation, based on scintillation and wavelength-shifting technologies and photosensor (SiPM and SiPM-like) technology. In particular, we focused our attention on ultra-compact radiation-hard EM calorimeters based on modular structures (RADiCAL modules) consisting of alternating layers of the very dense absorber and scintillating plates, read out via radiation hard wavelength shifting (WLS) solid fiber or capillary elements to photosensors positioned either proximately or remotely, depending upon their radiation tolerance. RADiCAL modules provide the capability to measure simultaneously and with high precision the position, energy and timing of EM showers. This paper provides an overview of the instrumentation and photosensor R&D associated with the RADiCAL program.

Anderson, Thomas↗
DOE OSTI2019

Radiation Hardness of Scintillation Detectors Based on Organic Plastic Scintillators and Optical Fibers

Scintillation detectors (SD) based on organic plastic scintillators and optical fibers are basic detectors at all modern accelerators and in astrophysics and neutrino physics experiments. In recent years, interest in SD has significantly increased due to the upcoming major upgrade of the LHC and the construction of new accelerators NICA, FAIR, FCC, etc. At the same time, requirements on the stability and reliability of SD operation under new conditions have become stricter, and their fulfillment largely depends on radiation hardness of scintillators, optical fibers, and photodetectors. The review presents the results of the radiation hardness investigations of various scintillators, optical fibers (scintillating, as well as wavelength-shifting and clear), and optical glues used to increase light collection from scintillators by fibers. The influence of various factors (dose, dose rate, type of radiation, scintillator materials, and fluors) on light output, light collection, and transmittance of the irradiated materials and their recovery is considered. Aging of scintillators caused by environmental effects (temperature, humidity) irrespective of radiation is also briefly considered.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2024

Intelligent Pixel Detectors: Towards a Radiation Hard ASIC with On-Chip Machine Learning in 28 nm CMOS

Detectors at future high energy colliders will face enormous technical challenges. Disentangling the unprecedented numbers of particles expected in each event will require highly granular silicon pixel detectors with billions of readout channels. With event rates as high as 40 MHz, these detectors will generate petabytes of data per second. To enable discovery within strict bandwidth and latency constraints, future trackers must be capable of fast, power efficient, and radiation hard data-reduction at the source. We are developing a radiation hard readout integrated circuit (ROIC) in 28nm CMOS with on-chip machine learning (ML) for future intelligent pixel detectors. We will show track parameter predictions using a neural network within a single layer of silicon and hardware tests on the first tape-outs produced with TSMC. Preliminary results indicate that reading out featurized clusters from particles above a modest momentum threshold could enable using pixel information at 40 MHz.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2020

Radiation-hard miniature optical engine with high bandwidth

Future silicon trackers will be operated in an intense radiation environment and require large volumes of data to be transmitted off detector. In addition, the optical modules must be of low mass in order to limit multiple scattering and nuclear interactions that would degrade the overall performance of the detector. Here, we present a miniature optical engine that satisfies these constraints. The optical engine consists of an ASIC driving a VCSEL (Vertical Cavity Surface Emitting Laser) array in an optical package. Two ASICs are designed to operate a 12-channel VCSEL array at 1.28 or 5.12 Gb/s per channel, which yields a total data rate of up to 60 Gb/s. The core transistors are fabricated in a 65 nm CMOS process which enhance the radiation-hardness. Each channel contains equalizer (CTLE) and clock-data recovery circuits (CDR) so that the ASIC can restore the highly distorted electrical signal after propagating through several meters of cables of small diameter. The equalizer, CDR, and VCSEL driver are configured via a digital I 2 C chip interface with triple redundant memory to mitigate single event upset (SEU) effects. The bias and modulation currents are controlled by a digital-to-analog converter (DAC). We present the design of the circuit together with the results of the simulations and preliminary measurements.

47 OTHER INSTRUMENTATION↗
DOE OSTI2017

The Determination of Radiation Hardness of Semiconductor Materials and Devices with Ion Beams

lon accelerator based techniques provide unique tools to gain insight into the phenomena underlying the formation of defects induced by energetic particles in semiconductor materials and their effects on the electronic features of the device. In recognition of the potential of these techniques, with the aim of enhancing the understanding of the mechanisms underlying the degradation of the performances of semiconductor devices induced by ionizing radiation, the IAEA established a Research Project, coordinated by the Physics Section (CRP F11016) entitled "Utilization of ion accelerators for studying and modelling of radiation induced defects in semiconductors and insulators" at the end of 2011. The objective of this IAEA Coordinated Research Project (CRP) was to enhance the capabilities of the interested Member States by facilitating their collective efforts to use accelerator-based ion irradiation of electronic materials in conjunction with available advanced characterization techniques to gain a deeper understanding of how different types of radiation influences the electronic properties of materials and devices, leading to an improved radiation hardness. A dynamic and productive research was stimulated by this CRP among collaborating partners, resulting in publications in scientific journals [CRP2016], educational and scientific software packages [W8, Forneris2014], and a number of collaborations among the participating research groups. Two of the most significant outcomes of this project are i) the experimental protocol, which rationalizes the use of the many existing characterization techniques adopted to investigate radiation effects in semiconductor devices and ii) the relevant theoretical approach to interpret the experimental data [Vittone2016 and references therein]. This publication integrates output of research articles published by the partners of the CRP and is aimed to provide an exhaustive description of the experimental protocol, the theoretical model with the relevant limits of application, the data analysis procedure, and the physical observables which can be effectively measured and which can be used for assessment of the radiation hardness of semiconductor devices. The intended audience of this report includes all those professionals and technologists working in ion beam functional analysis of semiconductor materials, solid-state physicists and engineers involved in the design of electronic devices working in radiation harsh environments.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Radiation-hardness studies with cerium-doped fused-silica fibers

In this work, we describe our R&D effort to develop potentially radiation-hard scintillating and wavelength shifting fibers by doping fused-silica with cerium. The cerium-doped optical fibers with different core structures and concentrations were exposed to gamma radiation (60Co) at different dose rates up to 100 kGy. We evaluated the radiation-induced degradation in photoluminescence, optical transmission, and recovery phenomena in the wavelength range from 300 to 700 nm. We were able to model the experimental data based on second-order rate equations where the fit parameters that govern the damage profile were utilized to predict recovery. We also measured the influence of radiation on the numerical aperture. Finally, we offer some thoughts on the use of these types of fibers in particle and nuclear physics detectors.

36 MATERIALS SCIENCE↗