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10 results on '"YAJIMA, N."'

1. Precise Measurements of Atmospheric Muon Fluxes with the BESS Spectrometer

Author

Motoki, M., Sanuki, T., Orito, S., Abe, K., Anraku, K., Asaoka, Y., Fujikawa, M., Fuke, H., Haino, S., Imori, M., Izumi, K., Maeno, T., Makida, Y., Matsui, N., Matsumoto, H., Matsunaga, H., Mitchell, J., Mitsui, T., Moiseev, A., Nishimura, J., Nozaki, M., Ormes, J., Saeki, T., Sasaki, M., Seo, E. S., Shikaze, Y., Sonoda, T., Streitmatter, R., Suzuki, J., Tanaka, K., Ueda, I., Wang, J. Z., Yajima, N., Yamagami, T., Yamamoto, A., Yamamoto, Y., Yamato, K., Yoshida, T., Yoshimura, K., Motoki, M., Sanuki, T., Orito, S., Abe, K., Anraku, K., Asaoka, Y., Fujikawa, M., Fuke, H., Haino, S., Imori, M., Izumi, K., Maeno, T., Makida, Y., Matsui, N., Matsumoto, H., Matsunaga, H., Mitchell, J., Mitsui, T., Moiseev, A., Nishimura, J., Nozaki, M., Ormes, J., Saeki, T., Sasaki, M., Seo, E. S., Shikaze, Y., Sonoda, T., Streitmatter, R., Suzuki, J., Tanaka, K., Ueda, I., Wang, J. Z., Yajima, N., Yamagami, T., Yamamoto, A., Yamamoto, Y., Yamato, K., Yoshida, T., and Yoshimura, K.

Abstract

The vertical absolute fluxes of atmospheric muons and muon charge ratio have been measured precisely at different geomagnetic locations by using the BESS spectrometer. The observations had been performed at sea level (30 m above sea level) in Tsukuba, Japan, and at 360 m above sea level in Lynn Lake, Canada. The vertical cutoff rigidities in Tsukuba (36.2 N, 140.1 E) and in Lynn Lake (56.5 N, 101.0 W) are 11.4 GV and 0.4 GV, respectively. We have obtained vertical fluxes of positive and negative muons in a momentum range from 0.6 to 20 GeV/c with systematic errors less than 3 % in both measurements. By comparing the data collected at two different geomagnetic latitudes, we have seen an effect of cutoff rigidity. The dependence on the atmospheric pressure and temperature, and the solar modulation effect have been also clearly observed. We also clearly observed the decrease of charge ratio of muons at low momentum side with at higher cutoff rigidity region., Comment: 35 pages, 9 figures. Submitted to Astroparticle Physics

Published
2002
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2. Precise Measurements of Atmospheric Muon Fluxes with the BESS Spectrometer

Author

Motoki, M., Sanuki, T., Orito, S., Abe, K., Anraku, K., Asaoka, Y., Fujikawa, M., Fuke, H., Haino, S., Imori, M., Izumi, K., Maeno, T., Makida, Y., Matsui, N., Matsumoto, H., Matsunaga, H., Mitchell, J., Mitsui, T., Moiseev, A., Nishimura, J., Nozaki, M., Ormes, J., Saeki, T., Sasaki, M., Seo, E. S., Shikaze, Y., Sonoda, T., Streitmatter, R., Suzuki, J., Tanaka, K., Ueda, I., Wang, J. Z., Yajima, N., Yamagami, T., Yamamoto, A., Yamamoto, Y., Yamato, K., Yoshida, T., Yoshimura, K., Motoki, M., Sanuki, T., Orito, S., Abe, K., Anraku, K., Asaoka, Y., Fujikawa, M., Fuke, H., Haino, S., Imori, M., Izumi, K., Maeno, T., Makida, Y., Matsui, N., Matsumoto, H., Matsunaga, H., Mitchell, J., Mitsui, T., Moiseev, A., Nishimura, J., Nozaki, M., Ormes, J., Saeki, T., Sasaki, M., Seo, E. S., Shikaze, Y., Sonoda, T., Streitmatter, R., Suzuki, J., Tanaka, K., Ueda, I., Wang, J. Z., Yajima, N., Yamagami, T., Yamamoto, A., Yamamoto, Y., Yamato, K., Yoshida, T., and Yoshimura, K.

Abstract

The vertical absolute fluxes of atmospheric muons and muon charge ratio have been measured precisely at different geomagnetic locations by using the BESS spectrometer. The observations had been performed at sea level (30 m above sea level) in Tsukuba, Japan, and at 360 m above sea level in Lynn Lake, Canada. The vertical cutoff rigidities in Tsukuba (36.2 N, 140.1 E) and in Lynn Lake (56.5 N, 101.0 W) are 11.4 GV and 0.4 GV, respectively. We have obtained vertical fluxes of positive and negative muons in a momentum range from 0.6 to 20 GeV/c with systematic errors less than 3 % in both measurements. By comparing the data collected at two different geomagnetic latitudes, we have seen an effect of cutoff rigidity. The dependence on the atmospheric pressure and temperature, and the solar modulation effect have been also clearly observed. We also clearly observed the decrease of charge ratio of muons at low momentum side with at higher cutoff rigidity region., Comment: 35 pages, 9 figures. Submitted to Astroparticle Physics

Published
2002
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3. Precise Measurement of Cosmic-Ray Proton and Helium Spectra with the BESS Spectrometer

Author

Sanuki, T., Motoki, M., Matsumoto, H., Seo, E. S., Wang, J. Z., Abe, K., Anraku, K., Asaoka, Y., Fujikawa, M., Imori, M., Maeno, T., Makida, Y., Matsui, N., Matsunaga, H., Mitchell, J., Mitsui, T., Moiseev, A., Nishimura, J., Nozaki, M., Orito, S., Ormes, J., Saeki, T., Sasaki, M., Shikaze, Y., Sonoda, T., Streitmatter, R., Suzuki, J., Tanaka, K., Ueda, I., Yajima, N., Yamagami, T., Yamamoto, A., Yoshida, T., Yoshimura, K., Sanuki, T., Motoki, M., Matsumoto, H., Seo, E. S., Wang, J. Z., Abe, K., Anraku, K., Asaoka, Y., Fujikawa, M., Imori, M., Maeno, T., Makida, Y., Matsui, N., Matsunaga, H., Mitchell, J., Mitsui, T., Moiseev, A., Nishimura, J., Nozaki, M., Orito, S., Ormes, J., Saeki, T., Sasaki, M., Shikaze, Y., Sonoda, T., Streitmatter, R., Suzuki, J., Tanaka, K., Ueda, I., Yajima, N., Yamagami, T., Yamamoto, A., Yoshida, T., and Yoshimura, K.

Abstract

We report cosmic-ray proton and helium spectra in energy ranges of 1 to 120 GeV and 1 to 54 GeV/nucleon, respectively, measured by a balloon flight of the BESS spectrometer in 1998. The magnetic-rigidity of the cosmic-rays was reliably determined by highly precise measurement of the circular track in a uniform solenoidal magnetic field of 1 Tesla. Those spectra were determined within overall uncertainties of +-5 % for protons and +- 10 % for helium nuclei including statistical and systematic errors., Comment: 12 pages, 4 figures

Published
2000
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4. Precise Measurement of Cosmic-Ray Proton and Helium Spectra with the BESS Spectrometer

Author

Sanuki, T., Motoki, M., Matsumoto, H., Seo, E. S., Wang, J. Z., Abe, K., Anraku, K., Asaoka, Y., Fujikawa, M., Imori, M., Maeno, T., Makida, Y., Matsui, N., Matsunaga, H., Mitchell, J., Mitsui, T., Moiseev, A., Nishimura, J., Nozaki, M., Orito, S., Ormes, J., Saeki, T., Sasaki, M., Shikaze, Y., Sonoda, T., Streitmatter, R., Suzuki, J., Tanaka, K., Ueda, I., Yajima, N., Yamagami, T., Yamamoto, A., Yoshida, T., Yoshimura, K., Sanuki, T., Motoki, M., Matsumoto, H., Seo, E. S., Wang, J. Z., Abe, K., Anraku, K., Asaoka, Y., Fujikawa, M., Imori, M., Maeno, T., Makida, Y., Matsui, N., Matsunaga, H., Mitchell, J., Mitsui, T., Moiseev, A., Nishimura, J., Nozaki, M., Orito, S., Ormes, J., Saeki, T., Sasaki, M., Shikaze, Y., Sonoda, T., Streitmatter, R., Suzuki, J., Tanaka, K., Ueda, I., Yajima, N., Yamagami, T., Yamamoto, A., Yoshida, T., and Yoshimura, K.

Abstract

We report cosmic-ray proton and helium spectra in energy ranges of 1 to 120 GeV and 1 to 54 GeV/nucleon, respectively, measured by a balloon flight of the BESS spectrometer in 1998. The magnetic-rigidity of the cosmic-rays was reliably determined by highly precise measurement of the circular track in a uniform solenoidal magnetic field of 1 Tesla. Those spectra were determined within overall uncertainties of +-5 % for protons and +- 10 % for helium nuclei including statistical and systematic errors., Comment: 12 pages, 4 figures

Published
2000
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5. Precision Measurement of Cosmic-Ray Antiproton Spectrum

Author

Orito, S., Maeno, T., Matsunaga, H., Abe, K., Anraku, K., Asaoka, Y., Fujikawa, M., Imori, M., Ishino, M., Makida, Y., Matsui, N., Matsumoto, H., Mitchell, J., Mitsui, T., Moiseev, A., Motoki, M., Nishimura, J., Nozaki, M., Ormes, J., Saeki, T., Sanuki, T., Sasaki, M., Seo, E. S., Shikaze, Y., Sonoda, T., Streitmatter, R., Suzuki, J., Tanaka, K., Ueda, I., Yajima, N., Yamagami, T., Yamamoto, A., Yoshida, T., Yoshimura, K., Orito, S., Maeno, T., Matsunaga, H., Abe, K., Anraku, K., Asaoka, Y., Fujikawa, M., Imori, M., Ishino, M., Makida, Y., Matsui, N., Matsumoto, H., Mitchell, J., Mitsui, T., Moiseev, A., Motoki, M., Nishimura, J., Nozaki, M., Ormes, J., Saeki, T., Sanuki, T., Sasaki, M., Seo, E. S., Shikaze, Y., Sonoda, T., Streitmatter, R., Suzuki, J., Tanaka, K., Ueda, I., Yajima, N., Yamagami, T., Yamamoto, A., Yoshida, T., and Yoshimura, K.

Abstract

The energy spectrum of cosmic-ray antiprotons has been measured in the range 0.18 to 3.56 GeV, based on 458 antiprotons collected by BESS in recent solar-minimum period. We have detected for the first time a distinctive peak at 2 GeV of antiprotons originating from cosmic-ray interactions with the interstellar gas. The peak spectrum is reproduced by theoretical calculations, implying that the propagation models are basically correct and that different cosmic-ray species undergo a universal propagation. Future BESS flights toward the solar maximum will help us to study the solar modulation and the propagation in detail and to search for primary antiproton components., Comment: REVTeX, 4 pages including 4 eps figures

Published
1999
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6. Precision Measurement of Cosmic-Ray Antiproton Spectrum

Author

Orito, S., Maeno, T., Matsunaga, H., Abe, K., Anraku, K., Asaoka, Y., Fujikawa, M., Imori, M., Ishino, M., Makida, Y., Matsui, N., Matsumoto, H., Mitchell, J., Mitsui, T., Moiseev, A., Motoki, M., Nishimura, J., Nozaki, M., Ormes, J., Saeki, T., Sanuki, T., Sasaki, M., Seo, E. S., Shikaze, Y., Sonoda, T., Streitmatter, R., Suzuki, J., Tanaka, K., Ueda, I., Yajima, N., Yamagami, T., Yamamoto, A., Yoshida, T., Yoshimura, K., Orito, S., Maeno, T., Matsunaga, H., Abe, K., Anraku, K., Asaoka, Y., Fujikawa, M., Imori, M., Ishino, M., Makida, Y., Matsui, N., Matsumoto, H., Mitchell, J., Mitsui, T., Moiseev, A., Motoki, M., Nishimura, J., Nozaki, M., Ormes, J., Saeki, T., Sanuki, T., Sasaki, M., Seo, E. S., Shikaze, Y., Sonoda, T., Streitmatter, R., Suzuki, J., Tanaka, K., Ueda, I., Yajima, N., Yamagami, T., Yamamoto, A., Yoshida, T., and Yoshimura, K.

Abstract

The energy spectrum of cosmic-ray antiprotons has been measured in the range 0.18 to 3.56 GeV, based on 458 antiprotons collected by BESS in recent solar-minimum period. We have detected for the first time a distinctive peak at 2 GeV of antiprotons originating from cosmic-ray interactions with the interstellar gas. The peak spectrum is reproduced by theoretical calculations, implying that the propagation models are basically correct and that different cosmic-ray species undergo a universal propagation. Future BESS flights toward the solar maximum will help us to study the solar modulation and the propagation in detail and to search for primary antiproton components., Comment: REVTeX, 4 pages including 4 eps figures

Published
1999
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7. Measurement of Low-Energy Cosmic-Ray Antiprotons at Solar Minimum

Author

Matsunaga, H., Orito, S., Matsumoto, H., Yoshimura, K., Moiseev, A., Anraku, K., Golden, R., Imori, M., Makida, Y., Mitchell, J., Motoki, M., Nishimura, J., Nozaki, M., Ormes, J., Saeki, T., Sanuki, T., Streitmatter, R., Suzuki, J., Tanaka, K., Ueda, I., Yajima, N., Yamagami, T., Yamamoto, A., Yoshida, T., Matsunaga, H., Orito, S., Matsumoto, H., Yoshimura, K., Moiseev, A., Anraku, K., Golden, R., Imori, M., Makida, Y., Mitchell, J., Motoki, M., Nishimura, J., Nozaki, M., Ormes, J., Saeki, T., Sanuki, T., Streitmatter, R., Suzuki, J., Tanaka, K., Ueda, I., Yajima, N., Yamagami, T., Yamamoto, A., and Yoshida, T.

Abstract

The absolute fluxes of the cosmic-ray antiprotons at solar minimum are measured in the energy range 0.18 to 1.4 GeV, based on 43 events unambiguously detected in BESS '95 data. The resultant energy spectrum appears to be flat below 1 GeV, compatible with a possible admixture of primary antiproton component with a soft energy spectrum, while the possibility of secondary antiprotons alone explaining the data cannot be excluded with the present accuracy. Further improvement of statistical accuracy and extension of the energy range are planned in future BESS flights., Comment: REVTeX, 4 pages including 4 eps figures. Submitted to PRL

Published
1998
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8. Measurement of Low-Energy Cosmic-Ray Antiprotons at Solar Minimum

Author

Matsunaga, H., Orito, S., Matsumoto, H., Yoshimura, K., Moiseev, A., Anraku, K., Golden, R., Imori, M., Makida, Y., Mitchell, J., Motoki, M., Nishimura, J., Nozaki, M., Ormes, J., Saeki, T., Sanuki, T., Streitmatter, R., Suzuki, J., Tanaka, K., Ueda, I., Yajima, N., Yamagami, T., Yamamoto, A., Yoshida, T., Matsunaga, H., Orito, S., Matsumoto, H., Yoshimura, K., Moiseev, A., Anraku, K., Golden, R., Imori, M., Makida, Y., Mitchell, J., Motoki, M., Nishimura, J., Nozaki, M., Ormes, J., Saeki, T., Sanuki, T., Streitmatter, R., Suzuki, J., Tanaka, K., Ueda, I., Yajima, N., Yamagami, T., Yamamoto, A., and Yoshida, T.

Abstract

The absolute fluxes of the cosmic-ray antiprotons at solar minimum are measured in the energy range 0.18 to 1.4 GeV, based on 43 events unambiguously detected in BESS '95 data. The resultant energy spectrum appears to be flat below 1 GeV, compatible with a possible admixture of primary antiproton component with a soft energy spectrum, while the possibility of secondary antiprotons alone explaining the data cannot be excluded with the present accuracy. Further improvement of statistical accuracy and extension of the energy range are planned in future BESS flights., Comment: REVTeX, 4 pages including 4 eps figures. Submitted to PRL

Published
1998
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9. A New Limit on the Flux of Cosmic Antihelium

Author

Saeki, T., Anraku, K., Orito, S., Ormes, J., Imori, M., Kimbell, B., Makida, Y., Matsumoto, H., Matsunaga, H., Mitchell, J., Motoki, M., Nishimura, J., Nozaki, M., Otoba, M., Sanuki, T., Streitmatter, R., Suzuki, J., Tanaka, K., Ueda, I., Yajima, N., Yamagami, T., Yamamoto, A., Yoshida, T., Yoshimura, K., Saeki, T., Anraku, K., Orito, S., Ormes, J., Imori, M., Kimbell, B., Makida, Y., Matsumoto, H., Matsunaga, H., Mitchell, J., Motoki, M., Nishimura, J., Nozaki, M., Otoba, M., Sanuki, T., Streitmatter, R., Suzuki, J., Tanaka, K., Ueda, I., Yajima, N., Yamagami, T., Yamamoto, A., Yoshida, T., and Yoshimura, K.

Abstract

A very sensitive search for cosmic-ray antihelium was performed using data obtained from three scientific flights of BESS magnetic rigidity spectrometer. We have not observed any antihelium; this places a model-independent upper limit (95 % C.L.) on the antihelium flux of 6*10**(-4) m**(-2)sr**(-1)s**(-1) at the top of the atmosphere in the rigidity region 1 to 16 GV, after correcting for the estimated interaction loss of antihelium in the air and in the instrument. The corresponding upper limit on the Hebar/He flux ratio is 3.1*10**(-6), 30 times more stringent than the limits obtained in similar rigidity regions with magnetic spectrometers previous to BESS., Comment: REVTeX, 4 pages (including 5 EPS figures). Submitted to PRL

Published
1997
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10. A New Limit on the Flux of Cosmic Antihelium

Author

Saeki, T., Anraku, K., Orito, S., Ormes, J., Imori, M., Kimbell, B., Makida, Y., Matsumoto, H., Matsunaga, H., Mitchell, J., Motoki, M., Nishimura, J., Nozaki, M., Otoba, M., Sanuki, T., Streitmatter, R., Suzuki, J., Tanaka, K., Ueda, I., Yajima, N., Yamagami, T., Yamamoto, A., Yoshida, T., Yoshimura, K., Saeki, T., Anraku, K., Orito, S., Ormes, J., Imori, M., Kimbell, B., Makida, Y., Matsumoto, H., Matsunaga, H., Mitchell, J., Motoki, M., Nishimura, J., Nozaki, M., Otoba, M., Sanuki, T., Streitmatter, R., Suzuki, J., Tanaka, K., Ueda, I., Yajima, N., Yamagami, T., Yamamoto, A., Yoshida, T., and Yoshimura, K.

Abstract

A very sensitive search for cosmic-ray antihelium was performed using data obtained from three scientific flights of BESS magnetic rigidity spectrometer. We have not observed any antihelium; this places a model-independent upper limit (95 % C.L.) on the antihelium flux of 6*10**(-4) m**(-2)sr**(-1)s**(-1) at the top of the atmosphere in the rigidity region 1 to 16 GV, after correcting for the estimated interaction loss of antihelium in the air and in the instrument. The corresponding upper limit on the Hebar/He flux ratio is 3.1*10**(-6), 30 times more stringent than the limits obtained in similar rigidity regions with magnetic spectrometers previous to BESS., Comment: REVTeX, 4 pages (including 5 EPS figures). Submitted to PRL

Published
1997
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