Browsing by Autor "Nobuaki Ochi"

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    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
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    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.
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    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.
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    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.
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    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
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    Un evento de tipo halo detectado con cámara de emulsiones y arreglo para chubascos en el Monte Chacaltaya
    (2004) Hiroshi Aoki; K. Hashimoto; N. Kawasumi; K. Honda; N. Inoue; N. Martinić; C. E. Navia; Nobuaki Ochi