P. N. Lebedev Physical Institute, Moscow, Rusian Academy of Sicences
Department of Physics, Moscow State University
D. N. Skobeltsyn Institute of Nuclear Physics, Moscow State University
P. N. Lebedev Physical Institute, Moscow, Rusian Academy of Sicences
D. N. Skobeltsyn Institute of Nuclear Physics, Moscow State University
P. N. Lebedev Physical Institute, Moscow, Rusian Academy of Sicences
Institute for Nuclear Research of Russian Academy of Science
P. N. Lebedev Physical Institute, Moscow, Rusian Academy of Sicences
Department of Physics, Moscow State University
Department of Physics, Moscow State University
Department of Physics, Moscow State University
D. N. Skobeltsyn Institute of Nuclear Physics, Moscow State University
D. N. Skobeltsyn Institute of Nuclear Physics, Moscow State University
D. N. Skobeltsyn Institute of Nuclear Physics, Moscow State University
Volsk Expeditionary Base of Lebedev Physical Institute
D. N. Skobeltsyn Institute of Nuclear Physics, Moscow State University
D. N. Skobeltsyn Institute of Nuclear Physics, Moscow State University
Department of Physics, Moscow State University
P. N. Lebedev Physical Institute, Moscow, Rusian Academy of Sciences
We report experimental results obtained by the wide-gap type emulsion chamber on board the first Japanese-Russo joint balloon, called RUNJOB (RUssia-Nippon JOint Balloon-program). Two balloons were launched subsequently from Kamchatka on July 1995,and the both were recovered successfully near Volga River. The exposure time is 130hrs for the first flight and 168hrs for the second. Altitude of the level flight is both approximately 32km on average, corresponding to 10g/cm^2. Total area of the emulsion chamber is 0.8m^2,and the thickness is 0.385 and 2.28 collision m.f.p.'s in vertical for proton- and iron-primaries, respectively. We detected 381 showers on Fuji-#200-type X-ray film, among which 174 showers originate in atmospheric secondary γ's, and the rest 207 come from nuclear components. The energy range covers 20∿200TeV for proton-primary, 3∿30TeV/nucleon for helium-primary, and 0.7∿5TeV/nucleon for iron-primary. It is remarkable that a very high energy proton with a few PeV is detected in the present experiment. It means no spectral break appears at around 10^<14>eV, in contrast to the maximum energy predicted by the current shock wave acceleration (first stage acceleration). This evidence indicates either some second stage acceleration occurs beyond a few hundreds TeV, or an extragalactic proton is detected directly. We give energy spectra for various elements (proton, helium, ..., iron) as well as a new method for the energy determination using the opening-angle of γ-ray core. We show also the feature of the PeV proton and discuss the estimation of primary energy. All-particle spectrum and the average mass of primary cosmic ray are also presented.
日露共同気球実験による高エネルギー 1 次宇宙線の観測
SA0167116.pdf
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