Precise measurements of cosmic-ray antiproton spectrum in a positive phase of the solar cycle

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

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


The BESS spectrometer has measured the energy spectrum of cosmic-ray antiprotons successively in 1993, 1995, 1997 and 1998. In total, 848 antiprotons were clearly identified in energy range 0.18 to 4.20 GeV based on magnetic-rigidity, time-of-flight, energy loss, and Cherenkov radiation measurements. The measured antiproton spectra and antiproton/proton ratios were nearly identical at the upper end of the instrumental energy range, which is consistent with theoretical calculations. In the low energy region, our data show variations that are somewhat larger than expected. This might be due to statistical fluctuation, or might suggest a contribution of primary antiprotons from novel sources.

Original languageEnglish
Pages (from-to)711-716
Number of pages6
JournalAdvances in Space Research
Issue number4
Publication statusPublished - 2001
Externally publishedYes

ASJC Scopus subject areas

  • Aerospace Engineering
  • Astronomy and Astrophysics
  • Geophysics
  • Atmospheric Science
  • Space and Planetary Science
  • General Earth and Planetary Sciences


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