Browsing by Autor "N. Ohmori"

Now showing 1 - 13 of 13

A halo event observed by hybrid detectors at Mt. Chacaltaya
(Elsevier BV, 2003) Hiroshi Aoki; K. Hashimoto; K. Honda; N. Inoue; N. Kawasumi; N. Martinić; C. E. Navia; N. Ohmori; A. Ohsawa; L. C. S. Oliveira
A Halo Event observed by the Hybrid Experiment at Mt. Chacaltaya
(Elsevier BV, 2005) Hiroshi Aoki; K. Hashimoto; K. Honda; N. Inoue; N. Kawasumi; N. Martinić; Christopher O'; Nobuaki Ochi; N. Ohmori; A. Ohsawa
A halo event observed with an emulsion chamber and air shower array at Mt Chacaltaya
(IOP Publishing, 2004) Hiroshi Aoki; K. Hashimoto; K. Honda; N. Inoue; N. Kawasumi; N. Martinić; Christopher O'; Nobuaki Ochi; N. Ohmori; A. Ohsawa
A hybrid experiment to operate simultaneously an air shower array, a hadron calorimeter and an emulsion chamber is under way at Mt Chacaltaya (5200 m, Bolivia). An event with a halo, a blackened area of ~1 cm on x-ray film of the emulsion chamber, was observed with the experiment. Information about the halo (Ehalo = 850 TeV) and on high energy particles of electromagnetic and hadronic components outside the halo (?E? = 632.5 TeV and ?E(?)h = 278.8 TeV with a detection threshold of 2 TeV) was obtained from emulsion chamber data. Details about low energy hadrons were determined from the hadron calorimeter data, and characteristics of the accompanying air shower (Ne = 7.0 ? 107, s = 0.59) were determined by the air shower array. We reconstruct the event, based on the observed data. The event is compared with simulated events, which supports the conclusion that nuclear interactions change their characteristics in the high energy region so as to result in stronger energy subdivision.
A systematic study of the hybrid experiment at Mt.Chacaltaya
(EDP Sciences, 2013) M. Tamada; Hiroshi Aoki; K. Honda; N. Inoue; N. Kawasumi; N. Martinić; Nobuaki Ochi; N. Ohmori; A. Ohsawa; H. Semba
In the hybrid experiment on Mt.Chacaltaya, we can observe three different components of airshowers, that is, air-shower size, burst-density and high energy families (a bundle of high energy particles). Burst-density in each block of hadron calorimeters are newly recalculated in simulations in oder to compare directly to the experimental data. Energy deposits in the scintillators of the hadron calorimeters are calculated using GEANT4 for every particle, incident upon the hadron calorimeter, in the air-showers simulated using CORSIKA, and are converted into burst-density, taking into consideration the exact structure of experimental hadron calorimeter. We study correlations among three observable components in the air-showers. Correlations between air-shower size and burst-density and those between air-shower size and accompanied family energy can be explained by model calculations by adjusting primary particle composition, the former correlation is in favor of proton-primaries but the latter iron-primaries. No model can describe well observed correlations between burst-density and family energy. That is, the observed family energy accompanied by the air-showers with larger burst-density is systematically smaller than that expected in the simulated events. Effects of a fluctuation in the cross-section of hadronic interactions are studied to settle the disagreement between experimental data and simulations.
A systematic study of the hybrid experiment at Mt.Chacaltaya
(EDP Sciences, 2013) M. Tamada; Hiroshi Aoki; K. Honda; N. Inoue; N. Kawasumi; N. Martinić; Nobuaki Ochi; N. Ohmori; A. Ohsawa; H. Semba
In the hybrid experiment on Mt.Chacaltaya, we can observe three different components of airshowers, that is, air-shower size, burst-density and high energy families (a bundle of high energy particles). Burst-density in each block of hadron calorimeters are newly recalculated in simulations in oder to compare directly to the experimental data. Energy deposits in the scintillators of the hadron calorimeters are calculated using GEANT4 for every particle, incident upon the hadron calorimeter, in the air-showers simulated using CORSIKA, and are converted into burst-density, taking into consideration the exact structure of experimental hadron calorimeter. We study correlations among three observable components in the air-showers. Correlations between air-shower size and burst-density and those between air-shower size and accompanied family energy can be explained by model calculations by adjusting primary particle composition, the former correlation is in favor of proton-primaries but the latter iron-primaries. No model can describe well observed correlations between burst-density and family energy. That is, the observed family energy accompanied by the air-showers with larger burst-density is systematically smaller than that expected in the simulated events. Effects of a fluctuation in the cross-section of hadronic interactions are studied to settle the disagreement between experimental data and simulations.
Cosmic ray nuclear interactions and EAS-triggered families observed by the Chacaltaya hybrid experiment
(Elsevier BV, 2008) Hiroshi Aoki; K. Honda; N. Inoue; Takaaki Ishii; N. Kawasumi; N. Martinić; Nobuaki Ochi; N. Ohmori; A. Ohsawa; M. Tamada
Simultaneous observation of families and accompanied air showers at Mt. Chacaltaya
(American Physical Society, 1996) N. Kawasumi; I. Tsushima; K. Honda; K. Hashimoto; T. Matano; N. Inoue; K. Mori; A. Ohsawa; M. Tamada; N. Ohmori
Simultaneous observations of families and accompanied air showers with emulsion chambers and the air shower array of electronic equipment at Mt. Chacaltaya (5200 m, 540 g/${\mathrm{cm}}^{2}$) reveal that families bear the data of nuclear interactions generated deep in the atmosphere. 47 outstanding families with \ensuremath{\Sigma}${\mathit{E}}_{\ensuremath{\gamma}}$\ensuremath{\ge}10 TeV are correlated with the accompanied air showers of the size ${10}^{5}$--${10}^{8}$. A scatter plot of the average family energy versus the size of the relative air shower requires further energy fractionizing process(es) in the propagation of high energy cosmic rays in the atmosphere, such as a larger dissipative mechanism in nuclear interaction, heavier chemical composition of the primary cosmic rays, etc. We reach the conclusion that nuclear interaction changes its features in the energy region ${\mathit{E}}_{0}$\ensuremath{\gtrsim}${10}^{16}$ eV, because the heavier composition, proposed so far, is not sufficient for the required dissipative process. A comparison with the data from the HADRON experiment at a similar altitude with a similar technique shows that no larger deviations are present between both experiments. \textcopyright{} 1996 The American Physical Society.
Simultaneous observation of families and accompanied air showers at Mt. Chacaltaya I
(Elsevier BV, 1997) K. Honda; N. Kawasumi; I. Tsushima; K. Hashimoto; T. Nishida; T. Matano; N. Inoue; A. Ohsawa; M. Tamada; N. Ohmori
Simultaneous observation of families and accompanied air showers at Mt. Chacaltaya II
(Elsevier BV, 1997) C. Aguirre; K. Hashimoto; K. Honda; N. Inoue; N. Kawasumi; N. Martinic; T. Matano; N. Ohmori; A. Ohsawa; F. Osco
Simultaneous observation of families and accompanied air showers at Mt. Chacaltaya. II. Study of the hadronic component in air showers
(American Physical Society, 2000) C. Aguirre; Hiroshi Aoki; K. Hashimoto; K. Honda; N. Inoue; N. Kawasumi; Yoshikazu Maeda; N. Martinić; T. Matano; N. Ohmori
An experimental setup of an air shower array, hadron calorimeter, and emulsion chamber is being carried out at Mt. Chacaltaya (5200 m, Bolivia), in order to study the hadron interaction and the primary cosmic rays in the energy region exceeding ${10}^{15}$ eV. The number of hadrons in the air shower, detected by the hadron calorimeter, is discussed mainly in this paper. A comparison with the simulation shows that the number of hadrons in the air shower is not compatible with that of the simulation, indicating that the Feynman scaling law is violated more strongly than the one assumed in the simulation at ${10}^{16}$ eV. The average mass number of the primary cosmic rays, estimated from the distribution of the number of hadrons, is $〈\mathrm{ln}A〉=2.8\ifmmode\pm\else\textpm\fi{}0.5$ at ${10}^{16}$ eV.
Solar Neutron Event in Association with a Large Solar Flare on 2000 November 24
(IOP Publishing, 2003) K. Watanabe; Y. Muraki; Y. Matsubara; Kazuaki Murakami; T. Sako; H. Tsuchiya; S. Masuda; M. Yoshimori; N. Ohmori; P. Miranda
Solar neutrons have been detected using the neutron monitor located at Mt. Chacaltaya, Bolivia, in association with a large solar flare on November 24, 2000. This is the first detection of solar neutrons by the neutron monitor that have been reported so far in solar cycle 23. The statistical significance of the detection is 5.5 sigma. In this flare, the intense emission of hard X-rays and gamma-rays has been observed by the Yohkoh Hard X-ray Telescope (HXT) and Gamma Ray Spectrometer (GRS), respectively. The production time of solar neutrons is better correlated with those of hard X-rays and gamma-rays than with the production time of soft X-rays. The observations of the solar neutrons on the ground have been limited to solar flares with soft X-ray class greater than X8 in former solar cycles. In this cycle, however, neutrons were detected associated with an X2.3 solar flare on November 24, 2000. This is the first report of the detection of solar neutrons on the ground associated with a solar flare with its X-ray class smaller than X8.
Study of hadronic component in air showers at Mt. Chacaltaya
(Elsevier BV, 2001) C. Aguirre; Hiroshi Aoki; K. Hashimoto; K. Honda; N. Inoue; N. Kawasumi; Yoshikazu Maeda; N. Martinić; N. Ohmori; A. Ohsawa
Study of primary cosmic ray composition from gamma ray families in air shower cores
(Elsevier BV, 1997) K. Honda; N. Kawasumi; I. Tsushima; K. Hashimoto; T. Nishida; T. Matano; N. Inoue; A. Ohsawa; M. Tamada; N. Ohmori