Browsing by Autor "H. Nakatani"

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Electrons in large air showers observed at 5200 m above sea level
(IOP Publishing, 1979) C. Aguirre; F. Kakimoto; K. Kamata; T. Kaneko; P. K. MacKeown; Y. Mizumoto; Kazuaki Murakami; M. Nagano; H. Nakatani; K. Nishi
Results are presented for the lateral distribution and the longitudinal development of electrons between an atmospheric depth of 550 g cm-2 and 1100 g cm-2 in air showers with sizes 3*106 to 5*109 observed at Mount Chacaltaya. The lateral distribution is compared with those determined at mountain altitudes and at sea level by other groups. The longitudinal development is also compared with the results of other groups and with theoretical predictions under various models of nuclear interactions.
Muons in large air showers observed at 5200 m above sea level
(IOP Publishing, 1979) C. Aguirre; A Treppi; F Kakimato; K Kamata; T. Kaneko; P. K. MacKeown; Y. Mizumoto; Kazuaki Murakami; H. Nakatani; K. Nishi
Results are presented for the lateral distribution of muons with energies above 600 MeV in air showers with electron sizes 107 to 109 observed at Mount Chacaltaya. Results are also presented for the muon size spectrum at 644 g cm-2 and the longitudinal development of muons from 550 g cm-2 to 990 g cm-2 for intensities 10-8 m-2 s-1 sr-1 to 10-10 m-2 s-1 sr-1.
The Energy Spectrum and the Chemical Composition of Primary Cosmic Rays with Energies from 10<sup>14</sup>to 10<sup>16</sup>eV
(IOP Publishing, 2004) S. Ogio; F. Kakimoto; Yuta Kurashina; O. Burgoa; Daiki Harada; H. Tokuno; H. Yoshii; A. Morizawa; E. Gotoh; H. Nakatani
We have measured extensive air showers with primary energies above 6 TeV at Mount Chacaltaya in Bolivia. The data were collected by an air shower array called the Minimum Air Shower (MAS) array starting in 2000 March. We applied an equi-intensity analysis method to the extensive air showers extended over the region of their maximum development. We varied the mixture of protons and iron in our simulations and compared these to the data to determine the mixing ratio of protons as a function of the primary energy. Using this, we derived the primary energy spectrum from 1014 to 5 × 1016 eV. Consequently, we conclude that the power-law index of the spectrum changes gradually around 1015.5 eV and that the obtained proton ratio decreases with increasing energy. We directly measured the longitudinal development of air showers generated by primaries with energies around the knee. We found that the average mass number of primary cosmic rays shows a steady increase with energy above 1014.5 eV and that the dominant component around the knee is not protons.