Latest Research on Double Hypernuclei Yoshimoto, Masahiro
Journal of The Society of Photographic Science and Technology of Japan,
2021, Letnik:
84, Številka:
2
Journal Article
Odprti dostop
Studies on double hypernuclei, which is doubly strange nuclei using the nuclear emulsion are being conducted in Gifu University. This article reports on the following issues; the analysis status of ...the latest double hypernuclear experiment E07, the mass measurement method of the double hypernuclei, the selection of the α-decay events using machine learning, the automatic search of π＋ mesons and μ＋ particles emitted from the π＋ decay, the high-resolution event analysis using an X-ray microscope, the latest stage development, and the future double hypernuclear experiment.
We successfully achieved the growth of a stacked layer composed of β-(AlxGa1−x)2O3/β-(InyGa1−y)2O3 on a (010) β-Ga2O3 substrate using mist chemical vapor deposition (CVD). X-ray diffraction and ...reciprocal space mapping analyses were conducted, elucidating that the multilayer structure of the β-(AlxGa1−x)2O3/β-(InyGa1−y)2O3 thin film exhibited excellent crystallinity and coherent growth. Scanning transmission electron microscopy further revealed a continuous atomic arrangement at the heterointerface of β-(AlxGa1−x)2O3/β-(InyGa1−y)2O3. Furthermore, the bandgap values of β-(AlxGa1−x)2O3 and β-(InyGa1−y)2O3 thin films were determined to be 5.21 and 4.62 eV, respectively, through electron energy-loss spectroscopy. Notably, a slight broadening was observed in the bandgap transition at the interface of β-(AlxGa1−x)2O3/β-(InyGa1−y)2O3. Energy dispersive x-ray spectroscopy analysis indicated that this phenomenon could be attributed to the diffusion of In into the β-(AlxGa1−x)2O3 thin film layer. These results support mist CVD as a promising growth technique for developing β-Ga2O3-based heterojunction devices.
A
bstract
In the DsTau experiment at the CERN SPS (NA65), an independent and direct way to measure tau neutrino production following high energy proton interactions was proposed. As the main source ...of tau neutrinos is a decay of
D
s
mesons, produced in proton-nucleus interactions, the project aims at measuring a differential cross section of this reaction. The experimental method is based on a use of high resolution emulsion detectors for effective registration of events with short lived particle decays. Here we present the motivation of the study, details of the experimental technique, and the first results of the analysis of the data collected during test runs, which prove feasibility of the full scale study of the process in future.
Abstract
Automatic nuclear emulsion readout systems have seen remarkable progress since the original idea was developed almost 40 years ago. After the success of its full application to a large-scale ...neutrino experiment, OPERA, a much faster readout system, the hyper-track selector (HTS), has been developed. HTS, which has an extremely wide-field objective lens, reached a scanning speed of 4700 cm$^2$/h, which is nearly 100 times faster than the previous system and therefore strongly promotes many new experimental projects. We will describe the concept, specifications, system structure, and achieved performance in this paper.
We inverted the 2010 Maule earthquake tsunami waveforms recorded at DART (Deep‐ocean Assessment and Reporting Tsunamis) stations in the Pacific Ocean by taking into account the effects of the ...seawater compressibility, elasticity of the solid Earth, and gravitational potential change. These effects slow down the tsunami speed and consequently move the slip offshore or updip direction, consistent with the slip distribution obtained by a joint inversion of DART, tide gauge, GPS, and coastal geodetic data. Separate inversions of only near‐field DART data and only far‐field DART data produce similar slip distributions. The former demonstrates that accurate tsunami arrival times and waveforms of trans‐Pacific tsunamis can be forecast in real time. The latter indicates that if the tsunami source area is as large as the 2010 Maule earthquake, the tsunami source can be accurately estimated from the far‐field deep‐ocean tsunami records without near‐field data.
Key Points
DART data inversion with new Green's functions produces slip distribution similar to joint inversion
Inversion of near‐field DART data can be used for real‐time tsunami forecast at far field
Tsunami source can be accurately estimated from far‐field DART data only
•We developed a methodology to construct broadband wavelength (BB) slip models suitable for strong motions and tsunami generation processes.•We estimated the BB slip model of the 1906 ...Ecuador-Colombia earthquake to fit observed tsunami waveforms and intensities.•High-frequency ground motion generation is greatly enhanced by the incorporation of short wavelength slips with strong localized stress drops.•Our methodology is an effective tool for the study of generation process of high frequency ground motions during large earthquakes.•BB slip models are appropriate to study variability in fault source process and its impact for tsunami and seismic hazard analysis.
The 1906/01/31 Ecuador-Colombia earthquake (Mw8.4–8.6), is one of the largest megathrust earthquakes that have occurred at the interface of the Nazca and South-American plates. Recently the source process of the earthquake has been re-examined using historical tsunami waveforms, yielding a slip distribution mainly near to the trench, and a smaller moment magnitude than previous estimations. Previous studies have shown that tsunami data can sufficiently constrain the long wavelength characteristics of slip during an earthquake. However to fully understand strong ground motion generation process during earthquakes in a broadband frequency range, the study of shorter wavelength slip, responsible for high frequency ground motion generation, is also necessary. In this study we use the tsunami-slip model of the 1906 earthquake, as well as comprehensive macro-seismic intensity estimations of the earthquake, to elaborate a broadband-wavelength (BB) source model appropriate for the generation of broadband frequency strong ground motions as well as tsunami modeling. Our results show that a BB slip model of the earthquake is able to satisfactorily reproduce observed intensity values as well as tsunami waveforms. Our BB slip model implies an increase in total moment magnitude to a value up to 8.6 respect to the estimation from tsunami data, which represent the contribution of short wavelength slips to seismic radiation. The methodology developed in this study is suitable to study the generation process of high frequency ground motions during large earthquakes.
Corundum structured metastable rhombohedral indium tin oxide (rh-ITO), which is known to grow as thin films, has attracted significant research interest; however, its properties, based on the Sn ...concentration, have not been evaluated in detail thus far. Herein, rh-ITO thin films comprising different Sn concentrations were grown on c-plane α-Al2O3 substrates with α-Ga2O3 buffer layers using the mist chemical vapor deposition method, and their properties were investigated. X-ray diffraction analysis revealed that c-plane rh-ITO thin films grew epitaxially at Sn concentrations of 0–10 at.%. The lowest thin film resistivity is determined to be approximately 3.3 × 10−4 Ω cm, which is sufficiently low for a transparent conductive oxide. The carrier concentration and mobility exhibited by the rh-ITO films were consistent with those of typical single-crystalline ITO films, which exhibited the most stable phase. The rh-ITO thin films exhibited high transmittance in the visible light region, and the absorption edge was blue-shifted with the increasing carrier concentration. This study demonstrates that rh-ITO can be used as a new transparent conductive oxide material for diverse applications.
Currently, β-Ga2O3 has attracted significant attention as a wide bandgap semiconductor, and numerous growth techniques are being explored to control its carrier concentration for various ...applications. In this study, we investigated the homoepitaxial growth of Si-doped β-Ga2O3 thin films on a Fe-doped β-Ga2O3 substrate using the mist chemical vapor deposition (CVD) technique developed in our group to obtain highly conductive thin films. Using mist CVD, we obtained highly crystalline Si-doped β-Ga2O3 thin films with a full-width at half-maximum of ∼40 arc sec for the (020) peak in the x-ray diffraction rocking curve. Atomic force microscopy studies indicated considerably smooth surfaces of the films with a small root mean square roughness (less than 0.5 nm). Furthermore, we controlled the carrier concentration in the range of 3.85 × 1018 to 2.58 × 1020 cm−3 by varying the Si concentration in the precursor solution. The film exhibits the highest conductivity of 2368 S/cm (mobility = 57.2 cm2/V s at the carrier concentration of 2.58 × 1020 cm−3). This study is expected to promote the application of β-Ga2O3 in devices.
GaAsBi alloys are potential candidates for near-infrared optoelectronic applications, such as light-emitting diodes, laser diodes, avalanche photodiodes, and solar cells. In this paper, photoexcited ...plasma in GaAs1-xBix/GaAs (1.7 ≤ x ≤ 8.6%) heterostructures grown by molecular beam epitaxy was investigated using Raman spectroscopy. The strong LO phonon-plasmon coupled mode (LOPC) was generated by continuous-wave laser excitation at room temperature. The upper branch of the LOPC mode (L+ mode) was clearly observed for Bi contents from x = 3.9–8.6%, which indicates that photoexcited carriers with relatively good carrier mobility were confined in the GaAsBi/GaAs heterostructure. The photoexcited carrier density that was obtained by line shape analysis of the Raman spectra based on a dielectric model increased as the Bi content increased from 1.7 to 6.4%. This indicates that carrier overflow from the GaAsBi layer was suppressed because of the larger conduction band offset at the GaAsBi/GaAs heterointerface. In addition, the optical mobility calculated using the damping constant of the photoexcited L+ mode gradually decreased with increasing Bi content. This may be attributed to an increased defect density with decreasing growth temperature. Our findings provide valuable insight into the development of high-performance optoelectronic devices based on GaAsBi alloys and show the potential of Raman spectroscopy for evaluation of carrier confinement in heterostructures.
We have newly applied Rapid Thermal Annealing (RTA) for the post-annealing of mist chemical-vapor-deposition (CVD)-derived Hf1−xZrxO2 (HZO) thin films. A ferroelectric polarization-electric field ...(P–E) curve was confirmed typically with noticeable polarization reversal currents. These ferroelectric properties of the HZO thin films provided quantitative estimation for Pr and Ec of ∼20 µC/cm2 and 1–1.5 MV/cm, respectively, compared to those reported from other growth methods, such as atomic-layer-deposition (ALD). It was revealed that the background leakage should be further reduced in a mist-CVD HZO film compared to those by ALD recently reported. The origin of the leakage was strongly related to the oxygen vacancy (Vo) generated in the film and near the HZO/bottom electrode interface. Nonetheless, it was found effective to use atmospheric pressure in air or oxygen in the post-RTA process for reducing leakage. In general, endurance behaviors for the mist-CVD HZO film revealed similar to those for samples prepared by other methods for both “wake-up” and “fatigue” phenomena, showing that the mist-CVD HZO film endured up to 2 × 109 counts. Finally, we expect that the mist-CVD HZO thin film would become a candidate for fabricating large-scale integration-oriented ferroelectric devices due to the intrinsic merits of the method.
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