Nami Kawasumi

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With the Akeno Giant Air Shower Array (AGASA), 581 cosmic rays above 10 19 eV, 47 above 4 × 10 19 eV, and 7 above 10 20 eV are observed until August 1998. Arrival direction distribution of these extremely high energy cosmic rays has been studied. While no significant large-scale anisotropy is found on the celestial sphere, some interesting clusters of(More)
The cosmic-ray energy spectrum above 10 18.5 eV is reported using the updated data set of the Akeno Giant Air Shower Array (AGASA) from February 1990 to October 1997. The energy spectrum extends beyond 10 20 eV and the energy gap between the highest energy event and the others is being filled up with recently observed events. The spectral shape suggests the(More)
Using data from more than ten-years of observations with the Akeno Giant Air Shower Array (AGASA), we published a result that the energy spectrum of ultra-high energy cosmic rays extends beyond the cutoff energy predicted by Greisen [1], and Zatsepin and Kuzmin [2]. In this paper, we reevaluate the energy determination method used for AGASA events with(More)
With the Akeno Giant Air Shower Array (AGASA), 581 cosmic rays above 10 19 eV, 47 above 4 × 10 19 eV, and 7 above 10 20 eV are observed until August 1998. Arrival direction distribution of these extremely high energy cosmic rays has been studied. While no significant large-scale anisotropy is found on the celestial sphere, some interesting clusters of(More)
Anisotropy in the arrival directions of cosmic rays with energies above 10 17 eV is studied using data from the Akeno 20 km 2 array and the Akeno Giant Air Shower Array (AGASA), using a total of about 114,000 showers observed over 11 years. In the first harmonic analysis, we have found strong anisotropy of ∼ 4% around 10 18 eV, corresponding to a chance(More)
We report a rst result on the cosmic ray energy spectrum above 3 10 18 eV measured by the Akeno Giant Air Shower Array (AGASA) from July 1990 to February 1994. The analysis method and the energy resolution of the AGASA experiment are described in some detail. The attening of the spectrum around 10 19 eV (ankle) is observed with a signicance of 2.9. If we(More)
A very energetic cosmic ray of energy about (1.72.6)10 20 eV was observed by the Akeno Giant Air Shower Array (AGASA) on December 3, 1993 from the direction of galactic longitude l=131 and galactic latitude b=-41 within an error circle of 1.0 radius. Shower characteristics such as lateral distribution and arrival time spread of charged particles, and(More)
We will report the observations of TeV gamma ray flares from Markarian 501 using Telescope Array Prototype. The observation were carried out continuously from the end of March to the end of July in 1997. The energy spectrum, and the time variation of the gamma ray intensities are shown. The intensity has been changed by the order of magnitude in this period(More)
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