The Experts below are selected from a list of 18570 Experts worldwide ranked by ideXlab platform
A. Bes - One of the best experts on this subject based on the ideXlab platform.
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A Study of the Radiation Tolerance of CVD Diamond to 70 MeV Protons, Fast Neutrons and 200 MeV Pions
Sensors, 2020Co-Authors: L. Bäni, A. Alexopoulos, M. Artuso, F. Bachmair, M. Bartosik, H. Beck, V. Bellini, V. Belyaev, B. Bentele, A. BesAbstract:We measured the Radiation Tolerance of commercially available diamonds grown by the Chemical Vapor Deposition process by measuring the charge created by a 120 GeV hadron beam in a 50 μm pitch strip detector fabricated on each diamond sample before and after irRadiation. We irradiated one group of samples with 70 MeV protons, a second group of samples with fast reactor neutrons (defined as energy greater than 0.1 MeV), and a third group of samples with 200 MeV pions, in steps, to (8.8±0.9) × 1015 protons/cm2, (1.43±0.14) × 1016 neutrons/cm2, and (6.5±1.4) × 1014 pions/cm2, respectively. By observing the charge induced due to the separation of electron–hole pairs created by the passage of the hadron beam through each sample, on an event-by-event basis, as a function of irRadiation fluence, we conclude all datasets can be described by a first-order damage equation and independently calculate the damage constant for 70 MeV protons, fast reactor neutrons, and 200 MeV pions. We find the damage constant for diamond irradiated with 70 MeV protons to be 1.62±0.07(stat)±0.16(syst)× 10−18 cm2/(pμm), the damage constant for diamond irradiated with fast reactor neutrons to be 2.65±0.13(stat)±0.18(syst)× 10−18 cm2/(nμm), and the damage constant for diamond irradiated with 200 MeV pions to be 2.0±0.2(stat)±0.5(syst)× 10−18 cm2/(πμm). The damage constants from this measurement were analyzed together with our previously published 24 GeV proton irRadiation and 800 MeV proton irRadiation damage constant data to derive the first comprehensive set of relative damage constants for Chemical Vapor Deposition diamond. We find 70 MeV protons are 2.60 ± 0.29 times more damaging than 24 GeV protons, fast reactor neutrons are 4.3 ± 0.4 times more damaging than 24 GeV protons, and 200 MeV pions are 3.2 ± 0.8 more damaging than 24 GeV protons. We also observe the measured data can be described by a universal damage curve for all proton, neutron, and pion irRadiations we performed of Chemical Vapor Deposition diamond. Finally, we confirm the spatial uniformity of the collected charge increases with fluence for polycrystalline Chemical Vapor Deposition diamond, and this effect can also be described by a universal curve
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Latest Results on the Radiation Tolerance of Diamond Detectors
2019Co-Authors: L. Bäni, A. Alexopoulos, M. Artuso, F. Bachmair, M. Bartosik, H. Beck, V. Bellini, V. Belyaev, B. Bentele, A. BesAbstract:We have measured the Radiation Tolerance of chemical vapor deposition (CVD) diamond against protons and neutrons. The relative Radiation damage constant of 24 GeV protons, 800 MeV protons, 70 MeV protons, and fast reactor neutrons is presented. The results are used to combine the measured data into a universal damage curve for diamond material.
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A study of the Radiation Tolerance of poly-crystalline and single-crystalline CVD diamond to 800 MeV and 24 GeV protons
J.Phys.D, 2019Co-Authors: L. Bäni, A. Alexopoulos, M. Artuso, F. Bachmair, M. Bartosik, H. Beck, V. Bellini, V. Belyaev, B. Bentele, A. BesAbstract:We have measured the Radiation Tolerance of poly-crystalline and single-crystalline diamonds grown by the chemical vapor deposition (CVD) process by measuring the charge collected before and after irRadiation in a 50 m pitch strip detector fabricated on each diamond sample. We irradiated one group of sensors with 800 MeV protons, and a second group of sensors with 24 GeV protons, in steps, to protons cm−2 and protons cm−2 respectively. We observe the sum of mean drift paths for electrons and holes for both poly-crystalline CVD diamond and single-crystalline CVD diamond decreases with irRadiation fluence from its initial value according to a simple damage curve characterized by a damage constant for each irRadiation energy and the irRadiation fluence. We find for each irRadiation energy the damage constant, for poly-crystalline CVD diamond to be the same within statistical errors as the damage constant for single-crystalline CVD diamond. We find the damage constant for diamond irradiated with 24 GeV protons to be and the damage constant for diamond irradiated with 800 MeV protons to be . Moreover, we observe the pulse height decreases with fluence for poly-crystalline CVD material and within statistical errors does not change with fluence for single-crystalline CVD material for both 24 GeV proton irRadiation and 800 MeV proton irRadiation. Finally, we have measured the uniformity of each sample as a function of fluence and observed that for poly-crystalline CVD diamond the samples become more uniform with fluence while for single-crystalline CVD diamond the uniformity does not change with fluence.
L. Bäni - One of the best experts on this subject based on the ideXlab platform.
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A Study of the Radiation Tolerance of CVD Diamond to 70 MeV Protons, Fast Neutrons and 200 MeV Pions
Sensors, 2020Co-Authors: L. Bäni, A. Alexopoulos, M. Artuso, F. Bachmair, M. Bartosik, H. Beck, V. Bellini, V. Belyaev, B. Bentele, A. BesAbstract:We measured the Radiation Tolerance of commercially available diamonds grown by the Chemical Vapor Deposition process by measuring the charge created by a 120 GeV hadron beam in a 50 μm pitch strip detector fabricated on each diamond sample before and after irRadiation. We irradiated one group of samples with 70 MeV protons, a second group of samples with fast reactor neutrons (defined as energy greater than 0.1 MeV), and a third group of samples with 200 MeV pions, in steps, to (8.8±0.9) × 1015 protons/cm2, (1.43±0.14) × 1016 neutrons/cm2, and (6.5±1.4) × 1014 pions/cm2, respectively. By observing the charge induced due to the separation of electron–hole pairs created by the passage of the hadron beam through each sample, on an event-by-event basis, as a function of irRadiation fluence, we conclude all datasets can be described by a first-order damage equation and independently calculate the damage constant for 70 MeV protons, fast reactor neutrons, and 200 MeV pions. We find the damage constant for diamond irradiated with 70 MeV protons to be 1.62±0.07(stat)±0.16(syst)× 10−18 cm2/(pμm), the damage constant for diamond irradiated with fast reactor neutrons to be 2.65±0.13(stat)±0.18(syst)× 10−18 cm2/(nμm), and the damage constant for diamond irradiated with 200 MeV pions to be 2.0±0.2(stat)±0.5(syst)× 10−18 cm2/(πμm). The damage constants from this measurement were analyzed together with our previously published 24 GeV proton irRadiation and 800 MeV proton irRadiation damage constant data to derive the first comprehensive set of relative damage constants for Chemical Vapor Deposition diamond. We find 70 MeV protons are 2.60 ± 0.29 times more damaging than 24 GeV protons, fast reactor neutrons are 4.3 ± 0.4 times more damaging than 24 GeV protons, and 200 MeV pions are 3.2 ± 0.8 more damaging than 24 GeV protons. We also observe the measured data can be described by a universal damage curve for all proton, neutron, and pion irRadiations we performed of Chemical Vapor Deposition diamond. Finally, we confirm the spatial uniformity of the collected charge increases with fluence for polycrystalline Chemical Vapor Deposition diamond, and this effect can also be described by a universal curve
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Latest Results on the Radiation Tolerance of Diamond Detectors
2019Co-Authors: L. Bäni, A. Alexopoulos, M. Artuso, F. Bachmair, M. Bartosik, H. Beck, V. Bellini, V. Belyaev, B. Bentele, A. BesAbstract:We have measured the Radiation Tolerance of chemical vapor deposition (CVD) diamond against protons and neutrons. The relative Radiation damage constant of 24 GeV protons, 800 MeV protons, 70 MeV protons, and fast reactor neutrons is presented. The results are used to combine the measured data into a universal damage curve for diamond material.
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results on Radiation Tolerance of diamond detectors
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2019Co-Authors: N Venturi, L. Bäni, A. Alexopoulos, M. Artuso, F. Bachmair, M. Bartosik, V. Bellini, J B Beacham, H C Beck, V. BelyaevAbstract:Abstract In sight of the luminosity increase of the High Luminosity-LHC (HL-LHC), most experiments at the CERN Large Hadron Collider (LHC) are planning upgrades for their innermost layers in the next 5–10 years. These upgrades will require more Radiation tolerant technologies than exist today. Usage of Chemical Vapor Deposition (CVD) diamond as detector material is one of the potentially interesting technologies for the upgrade. CVD diamond has been used extensively in the beam condition monitors of BaBar, Belle, CDF and all LHC experiments. Measurements of the Radiation Tolerance of the highest quality polycrystalline CVD material for a range of proton energies, pions and neutrons obtained with this material are presented. In addition, new results on the evolution of various semiconductor parameters as a function of the dose rate are described.
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A study of the Radiation Tolerance of poly-crystalline and single-crystalline CVD diamond to 800 MeV and 24 GeV protons
J.Phys.D, 2019Co-Authors: L. Bäni, A. Alexopoulos, M. Artuso, F. Bachmair, M. Bartosik, H. Beck, V. Bellini, V. Belyaev, B. Bentele, A. BesAbstract:We have measured the Radiation Tolerance of poly-crystalline and single-crystalline diamonds grown by the chemical vapor deposition (CVD) process by measuring the charge collected before and after irRadiation in a 50 m pitch strip detector fabricated on each diamond sample. We irradiated one group of sensors with 800 MeV protons, and a second group of sensors with 24 GeV protons, in steps, to protons cm−2 and protons cm−2 respectively. We observe the sum of mean drift paths for electrons and holes for both poly-crystalline CVD diamond and single-crystalline CVD diamond decreases with irRadiation fluence from its initial value according to a simple damage curve characterized by a damage constant for each irRadiation energy and the irRadiation fluence. We find for each irRadiation energy the damage constant, for poly-crystalline CVD diamond to be the same within statistical errors as the damage constant for single-crystalline CVD diamond. We find the damage constant for diamond irradiated with 24 GeV protons to be and the damage constant for diamond irradiated with 800 MeV protons to be . Moreover, we observe the pulse height decreases with fluence for poly-crystalline CVD material and within statistical errors does not change with fluence for single-crystalline CVD material for both 24 GeV proton irRadiation and 800 MeV proton irRadiation. Finally, we have measured the uniformity of each sample as a function of fluence and observed that for poly-crystalline CVD diamond the samples become more uniform with fluence while for single-crystalline CVD diamond the uniformity does not change with fluence.
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Latest results on Radiation Tolerance of diamond detectors
2018Co-Authors: A. Alexopoulos, L. Bäni, M. Artuso, F. Bachmair, M. Bartosik, H. Beck, V. Bellini, V. Belyaev, J B Beacham, B. BenteleAbstract:At present most experiments at the CERN Large Hadron Collider (LHC) are planning upgrades in the next 5-10 years for their innermost tracking layers as well as luminosity monitors to be able to take data as the luminosity increases and CERN moves toward the High Luminosity-LHC (HL-LHC). These upgrades will most likely require more Radiation tolerant technologies than exist today. As a result this is one area of intense research, and Chemical Vapour Deposition (CVD) diamond is one such technology. CVD diamond has been used extensively in beam condition monitors as the innermost detectors in the highest Radiation areas of all LHC experiments. This talk describes the preliminary Radiation Tolerance measurements of the highest quality polycrystalline CVD material for a range of proton energies and neutrons obtained with this material with the goal of elucidating the issues that should be addressed for future diamond based detectors. The talk presents the evolution of various semiconductor parameters as a function of dose.
Seth M Hubbard - One of the best experts on this subject based on the ideXlab platform.
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Radiation effects in thinned gaas photovoltaics incorporating dbrs for improved Radiation Tolerance of multijunctions
Photovoltaic Specialists Conference, 2019Co-Authors: Stephen J Polly, George T Nelson, Rao Tatavarti, Julia R Drozario, Seth M HubbardAbstract:Radiation Tolerance of a triple junction solar cell can be improved by thinning the GaAs middle junction and maintaining power conversion efficiency through the use of a distributed Bragg reflector. Simulations using Sentaurus RSoft show that current density lost through reduction of the GaAs base thickness can be recovered by increasing the optical path length through the device using photonic structures such as a distributed Bragg reflector (DBR). In this paper, the simulation is further compared to experiment focusing on the GaAs middle cell, where prior to growing the diode a conductive DBR is grown epitaxially using MOCVD. Internal and external quantum efficiency, as well as performance under 1-sun illumination, is presented showing nearly complete recovery of performance to opticallythick conditions, while using half the thickness of GaAs absorber. These devices were then exposed to 1 MeV electrons with total doses of 2×1014, 5×1014, and 1×1015 cm−2. Post-Radiation experimental results show improved J SC remaining factor, and absolute J SC , for the optically thin device incorporating a DBR. This allows an improvement of 0.36 mA/cm2 at a fluence of 1×1015 cm−2 over the optically thick control. This result was incorporated into a Ge-based triple junction simulation and predicts a 0.24% absolute efficiency improvement at 1×1015 cm−2 1 MeV e− fluence.
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incorporation of photonic structures for improved Radiation Tolerance of lattice matched triple junction solar cells
World Conference on Photovoltaic Energy Conversion, 2018Co-Authors: Stephen J Polly, George T Nelson, Julia Drrozario, Elisabeth L Mcclure, Rao Tatavarti, Seth M HubbardAbstract:A method of improving the Radiation Tolerance of a triple junction solar cell, lattice matched to germanium, by thinning the GaAs middle junction and maintaining power conversion efficiency through the use of a distributed Bragg reflector and patterned dielectric diffraction grating is discussed. Simulations using Sentaurus RSoft show that current density lost through reduction of the GaAs base thickness can be recovered by increasing the optical path length through the device using photonic structures such as a distributed Bragg reflector (DBR) and patterned dielectric gratings. In this paper, the simulation is further compared to experiment focusing on the GaAs middle cell, where prior to growing the diode a conductive DBR is grown epitaxially using MOCVD. Internal and external quantum efficiency, as well as performance under 1-sun illumination, is presented showing nearly complete recovery of performance to optically-thick conditions, while using half the thickness of GaAs absorber.
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strain effects on Radiation Tolerance of triple junction solar cells with inas quantum dots in the gaas junction
IEEE Journal of Photovoltaics, 2014Co-Authors: Christopher Kerestes, Cory D Cress, Stephen J Polly, Benjamin C Richards, D V Forbes, Yong Lin, Zac Bittner, Paul Sharps, Seth M HubbardAbstract:A comparison of quantum dot (QD) triple-junction solar cells (TJSCs) with the QD superlattice under tensile strain are compared with those under compressive strain and baseline devices to examine the effects of strain induced by the InAs QD layers in the middle junction. Theoretical results show samples with tensile-strained InAs QDs have lower defect formation energy while compressive-strained QDs have the greatest. Experimentally, it is found that tensile strain leads to degradation of i-region material at values of -706 ppm. Irradiating with 1-MeV electrons, TJSCs with tensile strain exhibit a faster degradation in Isc of the QD samples and slower degradation in Voc but overall faster degradation in efficiency compared with baseline TJSCs, regardless of the magnitude of tensile strain. Compressively strained QD TJSCs have similar degradation in Isc and slower degradation in Voc compared with baseline TJSCs. From this study, it is determined that a slightly compressive strain in the QD superlattice allows for the best performance pre- and postirRadiation for QD TJSCs based upon AM0 IV and quantum efficiency measurements and analysis. Fabricating devices with improvements determined from samples with varying strain leads to QD TJSCs with better Radiation Tolerance in terms of power output for 5, 10, 15, and 20 layers of QDs.
Izabela Szlufarska - One of the best experts on this subject based on the ideXlab platform.
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defect behavior and Radiation Tolerance of mab phases moalb and fe2alb2 with comparison to max phases
Acta Materialia, 2020Co-Authors: Hongliang Zhang, Jun Young Kim, Peter Richardson, Erich H Kisi, John Oconnor, Liqun Shi, Izabela SzlufarskaAbstract:Abstract MAB phases are a new class of layered ternary materials that have already shown a number of outstanding properties. Here, we investigate defect evolution and Radiation Tolerance of two MAB phases, MoAlB and Fe2AlB2, using a combination of experimental characterization and first-principles calculations. We find that Fe2AlB2 is more tolerant to Radiation-induced amorphization than MoAlB, both at 150 °C and at 300 °C. The results can be explained by the fact that the Mo Frenkel pair is unstable in MoAlB and as a result, irradiated MoAlB is expected to have a significant concentration of MoAl antisites, which are difficult to anneal even at 300 °C. We find that the Tolerance to Radiation-induced amorphization of MAB phases is lower than in MAX phases, but it is comparable to that of SiC. However, MAB phases do not show Radiation-induced cracking which is observed in MAX phases under the same irRadiation conditions. This study suggests that MAB phases might be a promising class of materials for applications that involve Radiation.
Blas P Uberuaga - One of the best experts on this subject based on the ideXlab platform.
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unprecedented irRadiation resistance of nanocrystalline tungsten with equiaxed nanocrystalline grains to dislocation loop accumulation
Acta Materialia, 2019Co-Authors: O Elatwani, Blas P Uberuaga, Enrique Martinez, E Esquivel, Eda Aydogan, J K Baldwin, S A MaloyAbstract:Abstract Nanocrystalline metals are often postulated as irRadiation tolerant materials due to higher grain boundary densities. The efficiency of these materials in mitigating irRadiation damage is still under investigation. Here, we present an in-situ transmission electron microscopy with ion irRadiation study on equiaxed 35 nm grained tungsten (NCW-35 nm) and compare its Radiation Tolerance, in terms of dislocation loop damage, to several other grades of tungsten with different grain sizes at two temperatures (RT and 1073 K). The NCW-35 nm was shown to possess significant higher Radiation Tolerance in terms of loop damage. As demonstrated by Kinetic Monte Carlo simulations, at least part of the higher Radiation Tolerance of the small grains is due to higher interstitial storage (at the grain boundaries) and defect recombination (in the grain interiors) in the small grain material. In addition, experimental observations reveal rapid and efficient dislocation loop absorption by the grain boundaries and this is considered the dominant factor for mass transport to the boundaries during irRadiation, enabling the remarkable Radiation Tolerance of 35 nm grained tungsten. This study demonstrates the possibility of attaining high Radiation tolerant materials, in terms of dislocation loop damage, by minimizing grain sizes in the nanocrystalline regime.
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Radiation Tolerance of nanocrystalline ceramics insights from yttria stabilized zirconia
Scientific Reports, 2015Co-Authors: John W Drazin, J A Valdez, Terry G. Holesinger, Blas P Uberuaga, Yongqiang Wang, Ricardo H R CastroAbstract:Materials for applications in hostile environments, such as nuclear reactors or radioactive waste immobilization, require extremely high resistance to Radiation damage, such as resistance to amorphization or volume swelling. Nanocrystalline materials have been reported to present exceptionally high Radiation-Tolerance to amorphization. In principle, grain boundaries that are prevalent in nanomaterials could act as sinks for point-defects, enhancing defect recombination. In this paper we present evidence for this mechanism in nanograined Yttria Stabilized Zirconia (YSZ), associated with the observation that the concentration of defects after irRadiation using heavy ions (Kr+, 400 keV) is inversely proportional to the grain size. HAADF images suggest the short migration distances in nanograined YSZ allow Radiation induced interstitials to reach the grain boundaries on the irRadiation time scale, leaving behind only vacancy clusters distributed within the grain. Because of the relatively low temperature of the irRadiations and the fact that interstitials diffuse thermally more slowly than vacancies, this result indicates that the interstitials must reach the boundaries directly in the collision cascade, consistent with previous simulation results. Concomitant Radiation-induced grain growth was observed which, as a consequence of the non-uniform implantation, caused cracking of the nano-samples induced by local stresses at the irradiated/non-irradiated interfaces.
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Radiation induced amorphization resistance and Radiation Tolerance in structurally related oxides
Nature Materials, 2007Co-Authors: K E Sickafus, J A Valdez, R W Grimes, A R Cleave, Ming Tang, Manabu Ishimaru, S M Corish, Christopher R Stanek, Blas P UberuagaAbstract:Ceramics destined for use in hostile environments such as nuclear reactors or waste immobilization must be highly durable and especially resistant to Radiation damage effects. In particular, they must not be prone to amorphization or swelling. Few ceramics meet these criteria and much work has been devoted in recent years to identifying Radiation-tolerant ceramics and the characteristics that promote Radiation Tolerance. Here, we examine trends in Radiation damage behaviour for families of compounds related by crystal structure. Specifically, we consider oxides with structures related to the fluorite crystal structure. We demonstrate that improved amorphization resistance characteristics are to be found in compounds that have a natural tendency to accommodate lattice disorder.
