M. Nishizawa
A5106731264- Astrophysics and Cosmic Phenomena
- Dark Matter and Cosmic Phenomena
- Particle Detector Development and Performance
- Solar and Space Plasma Dynamics
- Gamma-ray bursts and supernovae
- Radio Astronomy Observations and Technology
- Radiation Therapy and Dosimetry
- Neutrino Physics Research
- scientometrics and bibliometrics research
- Radiation Detection and Scintillator Technologies
- Particle physics theoretical and experimental studies
- Particle Accelerators and Free-Electron Lasers
- Academic Publishing and Open Access
- Ionosphere and magnetosphere dynamics
- Research Data Management Practices
- Pulsars and Gravitational Waves Research
- Technology and Data Analysis
- Social Media in Health Education
- Solar Radiation and Photovoltaics
- Delphi Technique in Research
- High-Energy Particle Collisions Research
- Head and Neck Cancer Studies
- Radio Wave Propagation Studies
- Astronomy and Astrophysical Research
- Scientific Computing and Data Management
National Institute of Informatics
2015-2024
Teikyo University
2018
Bridge University
2017
Shandong University
2010
Japan Science and Technology Agency
2007
Hirosaki University
2006
Saitama University
2006
Institute of High Energy Physics
2006
Chinese Academy of Sciences
2006
Yokohama National University
1991-2006
We report, for the first time, long-awaited detection of diffuse gamma rays with energies between 100 TeV and 1 PeV in Galactic disk. Particularly, all above 398 are observed apart from known gamma-ray sources compatible expectations hadronic emission scenario which originate decay $π^0$'s produced through interaction protons interstellar medium Galaxy. This is strong evidence that cosmic accelerated beyond our Galaxy spread over
The intensity of Galactic cosmic rays is nearly isotropic because the influence magnetic fields in Milky Way. Here, we present two-dimensional high-precision anisotropy measurement for energies from a few to several hundred teraelectronvolts (TeV), using large data sample Tibet Air Shower Arrays. Besides revealing finer details known anisotropies, new component ray sidereal time uncovered around Cygnus region direction. For cosmic-ray up TeV, all components anisotropies fade away, showing...
We present an updated all-particle energy spectrum of primary cosmic rays in a wide range from 1014 to 1017 eV using 5.5 × 107 events collected 2000 November through 2004 October by the Tibet-III air-shower array located 4300 m above sea level (an atmospheric depth 606 g cm−2). The size exhibits sharp knee at corresponding around 4 PeV. This work uses increased statistics and new simulation calculations for analysis. discuss our extensive Monte Carlo model dependencies involved final result,...
We present the large-scale sidereal anisotropy ofgalactic cosmic-ray intensity in multi-TeV region observed with Tibet-IIIair shower array during period from 1999 through 2003. The daily variation of cosmic rays this experiment shows an excess relative around $4\sim7 $ hours local time, as well a deficit 12 time. While amplitude is not significant when averaged over all declinations, individual declinaton bands becomes larger and clearer viewing direction moves toward south. maximum phase...
Abstract We report on the analysis of 10–1000 TeV large-scale sidereal anisotropy Galactic cosmic rays (GCRs) with data collected by Tibet Air Shower Array from 1995 October to 2010 February. In this analysis, we improve energy estimate and extend decl. range down −30°. find that maps above 100 are distinct at a multi-TeV band. The so-called tail-in loss-cone features identified low energies get less significant, new component appears ∼100 TeV. spatial distribution GCR intensity an excess...
view Abstract Citations (85) References (25) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Cosmic-Ray Energy Spectrum between 10 14.5 and 16.3 eV Covering the ``Knee'' Region Amenomori, M. ; Cao, Z. Dai, B. Ding, L. K. Feng, Y. X. Hibino, Hotta, N. Huang, Q. Huo, A. Jia, H. Jiang, G. Jiao, S. Kajino, F. Kasahara, Labaciren Liu, Mei, D. Meng, R. Mimaciren Mizutani, Mu, J. Nanjo, Nishizawa, Ohnishi, Ohta, I. Ouchi, T. Ren, Saito, To. Sakata, Shi, Shibata,...
The Tibet-III air shower array, consisting of 533 scintillation detectors, has been operating successfully at Yangbajing in Tibet, China since 1999. Using the data set collected by this array from 1999 November through 2005 November, we obtained energy spectrum γ-rays Crab Nebula, expressed a power law as (dJ/dE) = (2.09 ± 0.32) × 10−12(E/3 TeV)−2.96±0.14 cm−2 s−1 TeV−1 range 1.7–40 TeV. This result is consistent with other independent γ-ray observations imaging Cherenkov telescopes. In...
We report on a clear solar-cycle variation of the Sun's shadow in 10 TeV cosmic-ray flux observed by Tibet air shower array during full solar cycle from 1996 to 2009. In order clarify physical implications variation, we develop numerical simulations shadow, using potential field source surface model and current sheet (CSSS) for coronal magnetic field. find that intensity deficit simulated is very sensitive structure, better reproduced CSSS model. This first successful attempt evaluate models flux.
Though the maximum energy of charged cosmic ray observations exceeds 100 EeV, frontier gamma-ray is PeV. In past years, Tibet AS𝛾, HAWC and LHAASO opened a new window astronomy in sub-PeV to PeV range, which important unveil yet unknown accelerators our galaxy. As these 3 experiments are all located northern hemisphere, southern hemisphere have been awaited. Andes Large area PArticle detector for Cosmic physics Astronomy (ALPACA) air shower array experiment under construction Bolivian...
Results on steady TeV $\gamma$-ray point source search using data taken from the Tibet HD (Feb. 1997 -- Sep. 1999) and III (Nov. 1999 Oct. 2001) arrays are presented. From $0^{\circ}$ to $60^{\circ}$ in declination, significant excesses well-known Crab Nebula high state of flare type Markarian 421 observed. Because levels significance other positions not sufficiently high, 90% confidence level upper limits flux set assuming different power law spectra. To allow crosschecking, two...
The Tibet air shower array at an altitude of 4300 m has been in operation since January 1990. We have searched for continual emission 10-TeV gamma rays from the Crab Nebula, Cygnus X-3 and Hercules X-1 during period June 1990 through 1992. No dc excess is found these three sources. Flux upper limits above 10 TeV are obtained to be 1.2×10−12 cm−2 s−1 1.1×10−12 cm−2s−1 X-3, 0.58×10−12 95% C.L. This first observation, with array, sources energy region.Received 11...
Several strong TeV γ-ray flares were detected from Mrk 421 in the years 2000 and 2001 by Tibet III air shower array at a level of statistical significance 5.1 σ. was unprecedentedly active X-ray energies during this period, positive correlation found between change all-sky monitor Rossi X-Ray Timing Explorer flux flux. When power-law energy spectrum for γ-rays source is assumed, spectral index calculated to be -3.24 ± 0.69 most phase 2001. The observed consistent with those obtained via...
We will report the observations of TeV gamma ray flares from Markarian 501 using Telescope Array Prototype. The observation were carried out continuously end March to July in 1997. energy spectrum, and time variation intensities are shown. intensity has been changed by order magnitude this period possible quasi periodic oscillation 12.7days discovered.
We report observations of gamma-ray emissions with energies in the 100 TeV energy region from Cygnus our Galaxy. Two sources are significantly detected directions OB1 and OB2 associations. Based on their positional coincidences, we associate one a pulsar PSR J2032+4127 other mainly wind nebula PWN G75.2+0.1 moving away its original birthplace situated around centroid observed emission. This work would stimulate further studies particle acceleration mechanisms at these sources.
Since 1996, a hybrid experiment consisting of the emulsion chamber and burst detector array Tibet-II air-shower has been operated at Yangbajing (4300 m above sea level, 606 g/cm2) in Tibet. This can detect cores, called events, accompanied by air showers excess about 100 TeV. We observed 4300 events during 690 days operation selected 820 proton-induced with its primary energy 200 TeV using neural network method. Using this data set, we obtained spectrum protons range from to 1000 The...
The Tibet experiment, operating at Yangbajing (4300 m above sea level), is the lowest energy air shower array, and new high-density array constructed in 1996 sensitive to gamma-ray showers energies as low 3 TeV. With this Crab Nebula was observed multi-TeV gamma-rays a signal detected 5.5 sigma level. We also obtained spectrum of region TeV which partially overlaps those with imaging atmospheric Cerenkov telescopes. can be represented by power-law fit...
Data from the Tibet air-shower array were used to examine cosmic-ray shadows of Moon and Sun at energies around 10 TeV. The shadowing effect was clearly observed $5.8\ensuremath{\sigma}$ level for Moon, while shadow found in direction away by 0.86\ifmmode^\circ\else\textdegree\fi{} west 0.43\ifmmode^\circ\else\textdegree\fi{} south. geomagnetic field has also been cosmic rays Moon. deflection Sun's is briefly discussed connection with magnetic fields between Earth. This first observation...
Journal Article Coauthorship linkages between universities and industry in Japan Get access Yuan Sun, Sun Search for other works by this author on: Oxford Academic Google Scholar Masamitsu Negishi, Negishi Masaki Nishizawa Research Evaluation, Volume 16, Issue 4, December 2007, Pages 299–309, https://doi.org/10.3152/095820207X263619 Published: 01 2007
A 100 m2 muon detector (MD) was successfully constructed under the existing Tibet air shower (AS) array in late fall of 2007. The sensitivity AS to cosmic gamma rays can be improved by selecting muon-poor events with MD. Our MC simulation MD response reasonably agrees experimental data terms charge distribution for one-muon and background rejection power. Using collected taken from 2008 March 2010 February, we search continuous gamma-ray emission Crab Nebula above ∼100 TeV. No significant...
Abstract To investigate the impact of preprints on citation counts COVID-19-related papers, this study compares number citations received by drafts initially distributed as and later published in journals with those papers directly submitted to journals. The difference median between COVID-19 preprint-distributed 184 was tested using Mann-Whitney U test. results showed that 129 had a statistically significant higher count for compared p-value less than 0.05. In contrast, no papers. This...