Observation of cosmic-ray antiprotons at energies below 500 MeV

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

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Abstract

A search for cosmic-ray antiprotons was performed using a balloon-borne experiment with a superconducting magnetic rigidity spectrometer (BESS). We have detected four antiprotons in the kinetic energy range between 300 and 500 MeV, the first antiprotons to be identified by a direct mass measurement. The corresponding p»p flux ratio at the top of the atmosphere is found to be 1.2-0.65+1.0 × 10-5. No antiprotons were observed in the range between 175 and 300 MeV, resulting in a 90% C.L. upper limit on the flux ratio of 2.9 × 10-5.

Original languageEnglish
Pages (from-to)3792-3795
Number of pages4
JournalPhysical review letters
Volume75
Issue number21
DOIs
Publication statusPublished - 1995

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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    Yoshimura, K., Orito, S., Ueda, I., Anraku, K., Golden, R., Imori, M., Inaba, S., Kimbell, B., Kimura, N., Makida, Y., Matsumoto, H., Matsunaga, H., Mitchell, J., Motoki, M., Nishimura, J., Nozaki, M., Ormes, J., Saeki, T., Streitmatter, R., ... Yoshida, T. (1995). Observation of cosmic-ray antiprotons at energies below 500 MeV. Physical review letters, 75(21), 3792-3795. https://doi.org/10.1103/PhysRevLett.75.3792