A5048965764- Geology and Paleoclimatology Research
- Geomagnetism and Paleomagnetism Studies
- Muon and positron interactions and applications
- Geological and Geochemical Analysis
- Geological and Geophysical Studies
- Geochemistry and Elemental Analysis
- Methane Hydrates and Related Phenomena
- Atomic and Molecular Physics
- earthquake and tectonic studies
- Geological formations and processes
- Paleontology and Stratigraphy of Fossils
- Advanced NMR Techniques and Applications
- Quantum, superfluid, helium dynamics
- Reservoir Engineering and Simulation Methods
- High-pressure geophysics and materials
- Atomic and Subatomic Physics Research
- Cold Atom Physics and Bose-Einstein Condensates
- Geophysical and Geoelectrical Methods
- Particle accelerators and beam dynamics
- Advanced Chemical Physics Studies
- Drilling and Well Engineering
- Hydraulic Fracturing and Reservoir Analysis
- Rare-earth and actinide compounds
- Magnetic and Electromagnetic Effects
- Superconducting Materials and Applications
The University of Tokyo
2016-2025
Sphere Institute
2013-2025
Kanagawa University
2006-2024
Geological Survey of Japan
2007-2022
Tokyo Institute of Technology
1998-2022
The Open University of Japan
2018
Japan Agency for Marine-Earth Science and Technology
2017
University of Tsukuba
2010-2016
National Institute of Advanced Industrial Science and Technology
1997-2016
Hosei University
2004-2016
Zero- and low-field spin-relaxation functions have been studied for the first time by using positive muons, results are compared with stochastic theory of relaxation formulated Kubo Toyabe. The dipolar broadening zero-field has in detail. In Zr${\mathrm{H}}_{2}$, function ${\ensuremath{\mu}}^{+}$ found to decay ${(5)}^{\mathrm{\textonehalf{}}}$ times faster than high-field function, which is explained terms contribution nonsecular part interaction. Advantages method over conventional...
Zero- and longitudinal-field muon-spin relaxation (ZF \ensuremath{\mu}SR LF \ensuremath{\mu}SR) measurements have been applied to dilute-alloy spin glasses AuFe(1.0 1.4 at %) CuMn(1.1, 3, 5 at. %). A stochastic theory of has formulated, an analytic form zero-field (ZF) muon-spin-relaxation function derived describe the depolarization muon spins in static, dynamic, coexisting static dynamic random local fields from magnetic impurities. The observed experimental results for ${G}_{z}$(t) all...
A rock-magnetic and paleomagnetic study was conducted on a sediment core of about 4.4 m long taken from the northeastern part Japan Sea. The covers last 30 kyrs, which dated by nineteen radiocarbon (14C) ages. Remanent magnetization is carried dominantly magnetite. Reductive dissolution magnetic minerals occurs between 1.2 1.6 in depth (about 5–8 ka age). rapid downcore decrease anhysteretic remanent (ARM) begins at shallowest depth. Saturation isothermal (SIRM) follows, susceptibility (k)...
Increasing Asian dust fluxes, associated with late Cenozoic cooling and intensified glaciations, are conventionally thought to drive iron fertilization of phytoplankton productivity in the North Pacific, contributing ocean carbon storage drawdown atmospheric CO 2 . During early Pleistocene however, remained low despite higher only displaying glacial stage increases after mid-Pleistocene climate transition (~800 ka B.P.). We solve this paradox by analyzing an sequence, spanning last 3.6 My,...
We have observed the first laser-induced resonant transitions in antiprotonic helium atoms. These occur between metastable states and Auger dominated short lived states, show that anomalous longevity of antiprotons previously media results from formation high-n high-l atomic p\ifmmode\bar\else\textasciimacron\fi{}${\mathrm{He}}^{+}$. The transition with vacuum wavelength 597.259\ifmmode\pm\else\textpm\fi{}0.002 nm is tentatively assigned to (n,l)=(39,35)\ensuremath{\rightarrow}(38,34).
We have conducted a paleomagnetic study of six sediment cores taken from the equatorial Pacific, three West Caroline Basin and Manihiki Plateau, in order to make relative paleointensity stack during Matuyama late Gauss Chrons. The age bottom ranges 1.2 3.0 Ma. sediments show little downcore changes proxies magnetic grain size mineralogy are hence suitable for estimating paleointensity. is controlled by correlating variations concentration (magnetic susceptibility and/or anhysteretic remanent...
In the Southern Ocean, magnetic mineral concentration increases in glacial periods. The variation pattern closely resembles eolian dust flux records from Antarctic ice cores, but cause of linkage remains unclear, as is too small for source terrigenous materials Ocean. We have conducted an environmental study late Pleistocene sediments south Indian Ocean to investigate origin changes. Biogenic magnetites can be detected using characteristics almost no magnetostatic interactions and narrow...
We have discovered deep-sea mud that is extremely enriched in rare-earth elements and yttrium (together called REY) the Japanese Exclusive Economic Zone around Minamitorishima Island, western North Pacific Ocean. The maximum total REY concentration reaches approximately 7000 ppm, which much higher than reported for conventional deposits on land other known potential resources ocean. REY-rich characterized by abundant phillipsite biogenic calcium phosphate. In addition, stratigraphic layer...
Six laser-resonant transitions have been detected in metastable antiprotonic helium atoms produced at the CERN Antiproton Decelerator. They include UV from last states $v\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}n\ensuremath{-}\ensuremath{\ell}\ensuremath{-}1\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0$ and 1 cascades. Zero-density frequencies were obtained measured pressure shifts with fractional precisions between...
A continuous record of the inclination and intensity Earth's magnetic field, during past 2.25 million years, was obtained from a marine sediment core 42 meters in length. This reveals presence 100,000-year periodicity intensity, which suggests that field is modulated by orbital eccentricity. The correlation between shifted antiphase to in-phase, corresponding polarity change reversed normal. To explain observation, we propose model strength geocentric axial dipole varies with periodicity,...
A radio frequency quadrupole decelerator and achromatic momentum analyzer were used to decelerate antiprotons produce $\overline{p}^{4}\mathrm{H}\mathrm{e}^{+}$ $\overline{p}^{3}\mathrm{H}\mathrm{e}^{+}$ atoms in ultra-low-density targets, where collision-induced shifts of the atomic transition frequencies negligible. The at near-vacuo conditions measured by laser spectroscopy fractional precisions $(6--19)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}$. By comparing these with QED...
The Mariana Trough is an actively opening backarc basin in the western Pacific. trough formed by extension which longitudinally split earlier arc massif creating a crescent‐shaped between remnant West Ridge and eastern active volcanoes of Arc. Opening increases southward from Volcano Islands near 24°N where two arcs join. At 18°N central widest may be primarily seafloor spreading. We present synthesis closely spaced shipboard gravity, magnetic, bathymetry measurements northern (20°–24°N),...
High-resolution spectroscopy of ${\ensuremath{\pi}}^{+}$ from ${K}^{\ensuremath{-}}$ absorption at rest has been used for the first time to identify ${\ensuremath{\Sigma}}^{\ensuremath{-}}$ hypernuclear states. The observed spectrum a ${(\mathrm{CH})}_{n}$ target revealed ${p}_{\frac{3}{2}}\ensuremath{-}{p}_{\frac{1}{2}}$ doublet $_{{\ensuremath{\Sigma}}^{\ensuremath{-}}}^{12}\mathrm{Be}$ with narrow widths. spin-orbit splitting is deduced be 5 MeV, 0.8 times that nucleons.
The diffusion of positive muons (${\ensuremath{\mu}}^{+}$\ensuremath{\approxeq}0.11\ifmmode\times\else\texttimes\fi{}proton mass) in copper was studied experimentally by the zero-field muon-spin-relaxation method a temperature (T) range from 70 mK to 190 K, using pulsed muon beam suitable for present method. measurements were performed three samples different purities see effect impurities on nature ${\ensuremath{\mu}}^{+}$ diffusion. We find that (hopping) rate \ensuremath{\nu} ultrapure...