The Experts below are selected from a list of 270 Experts worldwide ranked by ideXlab platform
Susumu Takada - One of the best experts on this subject based on the ideXlab platform.
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X-Ray Detection Using Superconducting Tunnel Junction Shaped Normal-Distribution-Function
IEICE Transactions on Electronics, 2007Co-Authors: Tohru Taino, Hiroaki Myoren, Tomohiro Nishihara, Koichi Hoshino, Hiromi Sato, Hirohiko M. Shimizu, Susumu TakadaAbstract:A Normal-Distribution-Function-shaped superconducting tunnel junction (NDF-STJ) which consists of Nb/Al-AlO x /Al/Nb has been fabricated as an X-ray detector. Current - voltage characteristics were measured at 0.4 K using three kinds of STJs, which have the dispersion parameters σ of 0.25, 0.45 and 0.75. These STJs showed very low subgap leakage current of about 5 nA. By irradiating with 5.9 keV X-rays, we obtained the spectrum of these NDF-STJs. They showed good energy resolution with small magnetic fields of below 3 mT, which is about one-tenth of those for conventional-shaped STJs.
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Fiske Steps of Josephson Tunnel Junctions Formed with Normal-Distribution Function
Japanese Journal of Applied Physics, 2002Co-Authors: Katsuya Kikuchi, Hiroaki Myoren, Takeshi Iizuka, Susumu TakadaAbstract:Magnetic field dependence of Fiske steps has been investigated using Nb/Al–AlOx/Nb tunnel junctions formed with a Normal-Distribution Function with a dispersion parameter of σ= 0.45. Fiske steps are due to the different resonance mode appearing in the current–voltage characteristics when an external magnetic field is applied to the junctions at 4.2 K. Both positions in the voltage scale and current amplitude of Fiske steps were systematically measured. We found that the amplitudes of the Fiske steps increased gradually, and then decreased monotonically with an increase in magnetic field. All Fiske steps almost completely disappeared at a magnetic field of less than 1 mT, at which the dc Josephson critical current also decreased to less than 10-3 of the maximum. The position of Fiske steps in the voltage scale was analyzed using a diamond-shaped junction which corresponds to a 45-degree-rotated square junction.
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Normal Distribution Function shaped superconducting tunnel junctions with Ta electrodes
Physica C-superconductivity and Its Applications, 2002Co-Authors: Hiroaki Myoren, Katsuya Kikuchi, Takeshi Iizuka, Yuki Kogure, Ryo Abe, Susumu TakadaAbstract:We prepared Normal Distribution Function shaped (NDF-shaped) superconducting tunnel junctions (STJs) with Ta electrodes. Using two different phases of Ta, we successfully prepared STJs with bcc-Ta and β-Ta electrodes. The critical current of the NDF-shaped STJs with Ta electrodes showed an exponential decrease for the applied magnetic field. We determined the coherence length for bcc-Ta and β-Ta combined with Nb at 0.4 K. Coherence lengths were determined to be 21 nm for bcc-Ta and 16 nm for β-Ta combined with Nb. For the quasiparticle trapping and amplification, β-Ta is expected to be a good electrode combined with Nb because of the short coherence length.
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Normal-Distribution-Function-shaped Josephson tunnel junctions
Applied Physics Letters, 2000Co-Authors: Katsuya Kikuchi, Hiroaki Myoren, Takeshi Iizuka, Susumu TakadaAbstract:We have investigated the magnetic field dependence of the Josephson tunnel junctions whose shape is defined with a Normal-Distribution Function. It was revealed that the Normal-Distribution-shaped Josephson tunnel junctions show an exponential decay and no side lobes of the Josephson current as the external magnetic field is increased. This behavior was confirmed experimentally by using the Nb/AlOx/Nb tunnel junctions with a Josephson critical current density of Jc=50 A/cm2, and an area of 10 000 μm2 corresponding to the “small” junction region. Normal-Distribution junctions should have a potential for wide applications to photon detection since the external magnetic field to suppress the Josephson current can be lowered to less than one tenth that of other junctions reported.
Hiroaki Myoren - One of the best experts on this subject based on the ideXlab platform.
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X-Ray Detection Using Superconducting Tunnel Junction Shaped Normal-Distribution-Function
IEICE Transactions on Electronics, 2007Co-Authors: Tohru Taino, Hiroaki Myoren, Tomohiro Nishihara, Koichi Hoshino, Hiromi Sato, Hirohiko M. Shimizu, Susumu TakadaAbstract:A Normal-Distribution-Function-shaped superconducting tunnel junction (NDF-STJ) which consists of Nb/Al-AlO x /Al/Nb has been fabricated as an X-ray detector. Current - voltage characteristics were measured at 0.4 K using three kinds of STJs, which have the dispersion parameters σ of 0.25, 0.45 and 0.75. These STJs showed very low subgap leakage current of about 5 nA. By irradiating with 5.9 keV X-rays, we obtained the spectrum of these NDF-STJs. They showed good energy resolution with small magnetic fields of below 3 mT, which is about one-tenth of those for conventional-shaped STJs.
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Fiske Steps of Josephson Tunnel Junctions Formed with Normal-Distribution Function
Japanese Journal of Applied Physics, 2002Co-Authors: Katsuya Kikuchi, Hiroaki Myoren, Takeshi Iizuka, Susumu TakadaAbstract:Magnetic field dependence of Fiske steps has been investigated using Nb/Al–AlOx/Nb tunnel junctions formed with a Normal-Distribution Function with a dispersion parameter of σ= 0.45. Fiske steps are due to the different resonance mode appearing in the current–voltage characteristics when an external magnetic field is applied to the junctions at 4.2 K. Both positions in the voltage scale and current amplitude of Fiske steps were systematically measured. We found that the amplitudes of the Fiske steps increased gradually, and then decreased monotonically with an increase in magnetic field. All Fiske steps almost completely disappeared at a magnetic field of less than 1 mT, at which the dc Josephson critical current also decreased to less than 10-3 of the maximum. The position of Fiske steps in the voltage scale was analyzed using a diamond-shaped junction which corresponds to a 45-degree-rotated square junction.
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Normal Distribution Function shaped superconducting tunnel junctions with Ta electrodes
Physica C-superconductivity and Its Applications, 2002Co-Authors: Hiroaki Myoren, Katsuya Kikuchi, Takeshi Iizuka, Yuki Kogure, Ryo Abe, Susumu TakadaAbstract:We prepared Normal Distribution Function shaped (NDF-shaped) superconducting tunnel junctions (STJs) with Ta electrodes. Using two different phases of Ta, we successfully prepared STJs with bcc-Ta and β-Ta electrodes. The critical current of the NDF-shaped STJs with Ta electrodes showed an exponential decrease for the applied magnetic field. We determined the coherence length for bcc-Ta and β-Ta combined with Nb at 0.4 K. Coherence lengths were determined to be 21 nm for bcc-Ta and 16 nm for β-Ta combined with Nb. For the quasiparticle trapping and amplification, β-Ta is expected to be a good electrode combined with Nb because of the short coherence length.
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Normal-Distribution-Function-shaped Josephson tunnel junctions
Applied Physics Letters, 2000Co-Authors: Katsuya Kikuchi, Hiroaki Myoren, Takeshi Iizuka, Susumu TakadaAbstract:We have investigated the magnetic field dependence of the Josephson tunnel junctions whose shape is defined with a Normal-Distribution Function. It was revealed that the Normal-Distribution-shaped Josephson tunnel junctions show an exponential decay and no side lobes of the Josephson current as the external magnetic field is increased. This behavior was confirmed experimentally by using the Nb/AlOx/Nb tunnel junctions with a Josephson critical current density of Jc=50 A/cm2, and an area of 10 000 μm2 corresponding to the “small” junction region. Normal-Distribution junctions should have a potential for wide applications to photon detection since the external magnetic field to suppress the Josephson current can be lowered to less than one tenth that of other junctions reported.
Katsuya Kikuchi - One of the best experts on this subject based on the ideXlab platform.
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Fiske Steps of Josephson Tunnel Junctions Formed with Normal-Distribution Function
Japanese Journal of Applied Physics, 2002Co-Authors: Katsuya Kikuchi, Hiroaki Myoren, Takeshi Iizuka, Susumu TakadaAbstract:Magnetic field dependence of Fiske steps has been investigated using Nb/Al–AlOx/Nb tunnel junctions formed with a Normal-Distribution Function with a dispersion parameter of σ= 0.45. Fiske steps are due to the different resonance mode appearing in the current–voltage characteristics when an external magnetic field is applied to the junctions at 4.2 K. Both positions in the voltage scale and current amplitude of Fiske steps were systematically measured. We found that the amplitudes of the Fiske steps increased gradually, and then decreased monotonically with an increase in magnetic field. All Fiske steps almost completely disappeared at a magnetic field of less than 1 mT, at which the dc Josephson critical current also decreased to less than 10-3 of the maximum. The position of Fiske steps in the voltage scale was analyzed using a diamond-shaped junction which corresponds to a 45-degree-rotated square junction.
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Normal Distribution Function shaped superconducting tunnel junctions with Ta electrodes
Physica C-superconductivity and Its Applications, 2002Co-Authors: Hiroaki Myoren, Katsuya Kikuchi, Takeshi Iizuka, Yuki Kogure, Ryo Abe, Susumu TakadaAbstract:We prepared Normal Distribution Function shaped (NDF-shaped) superconducting tunnel junctions (STJs) with Ta electrodes. Using two different phases of Ta, we successfully prepared STJs with bcc-Ta and β-Ta electrodes. The critical current of the NDF-shaped STJs with Ta electrodes showed an exponential decrease for the applied magnetic field. We determined the coherence length for bcc-Ta and β-Ta combined with Nb at 0.4 K. Coherence lengths were determined to be 21 nm for bcc-Ta and 16 nm for β-Ta combined with Nb. For the quasiparticle trapping and amplification, β-Ta is expected to be a good electrode combined with Nb because of the short coherence length.
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Normal-Distribution-Function-shaped Josephson tunnel junctions
Applied Physics Letters, 2000Co-Authors: Katsuya Kikuchi, Hiroaki Myoren, Takeshi Iizuka, Susumu TakadaAbstract:We have investigated the magnetic field dependence of the Josephson tunnel junctions whose shape is defined with a Normal-Distribution Function. It was revealed that the Normal-Distribution-shaped Josephson tunnel junctions show an exponential decay and no side lobes of the Josephson current as the external magnetic field is increased. This behavior was confirmed experimentally by using the Nb/AlOx/Nb tunnel junctions with a Josephson critical current density of Jc=50 A/cm2, and an area of 10 000 μm2 corresponding to the “small” junction region. Normal-Distribution junctions should have a potential for wide applications to photon detection since the external magnetic field to suppress the Josephson current can be lowered to less than one tenth that of other junctions reported.
Fuchen Wang - One of the best experts on this subject based on the ideXlab platform.
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Effect of heat treatment on structure and gasification reactivity of petroleum coke
International Journal of Coal Science & Technology, 2016Co-Authors: Li Chao, Zhijie Zhou, Zhenghua Dai, Ji Yang, Xin Liu, Fuchen WangAbstract:Petroleum coke was thermally treated on a fixed bed reactor in a temperature range of 1173–1673 K. The changes of the elemental composition and crystalline structure of petroleum coke, with heat treatments as well as the gasification reactivity of the heat-treated petroleum cokes were investigated. The results showed that the petroleum coke was carbonized and graphitized to a higher degree with increasing heating temperature, while the gasification reactivity decreased. The treatment at temperatures of 1173 and 1473 K significantly enlarged the specific surface area and the pore volume of petroleum coke. Both the specific surface area and the pore volume decreased at 1673 K. An empirical Normal Distribution Function model (NDFM) was found to fit the gasification rates of petroleum coke well. The correlation coefficient of petroleum coke by Normal Distribution Function model at different heat treatment temperatures is between 0.93 and 0.95.
John D. Vedder - One of the best experts on this subject based on the ideXlab platform.
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An invertible approximation to the Normal Distribution Function
Computational Statistics & Data Analysis, 1993Co-Authors: John D. VedderAbstract:Abstract A new, closed form approximation to the Normal Distribution Function is derived. It combines a simple form over the entire real line with appreciable accuracy. Its inverse is derived as well. The errors of both the approximation and its inverse are discussed, as are its first few moments. The approximation is useful whenever a simple, closed form, analytical approximation would be advantageous and accuracy requirements are moderate.
