Cosmic ray helium isotopes from the BESS-Polar I experiment

N. Picot-Clemente, K. Abe, H. Fuke, S. Haino, T. Hams, A. Itazaki, K. C. Kim, T. Kumazawa, M. H. Lee, Y. Makida, S. Matsuda, K. Matsumoto, J. W. Mitchell, Z. Myers, J. Nishimura, M. Nozaki, R. Orito, J. F. Ormes, M. Sasaki, E. S. SeoY. Shikaze, R. E. Streitmatter, J. Suzuki, Y. Takasugi, K. Takeuchi, K. Tanaka, T. Yamagami, A. Yamamoto, T. Yoshida, K. Yoshimura

Research output: Contribution to conferencePaperpeer-review


The first flight of the Balloon-Borne Experiment with a Superconducting Spectrometer (BESS-Polar I) in Antarctica collected about 900 million cosmic ray events during 8.5 days in 2004. Particle charge was determined from energy loss in the scintillators, rigidity by reconstructing each particle trajectory in the magnetic field, and velocity by utilizing time of flights counters. These measurements can clearly identify hydrogen and helium isotopes among the incoming particles. These isotopes are generally believed to result from nuclear interactions of primaries with the interstellar medium. Measurement of their flux is expected to provide important information on cosmic ray sources and particle propagation in interstellar space. The presentation will focus on determination of the helium isotope flux in the kinetic energy per nucleon range 0.1 GeV/n to about 1.5 GeV/n. After quickly introducing the BESS-Polar I detector, the dedicated analysis to differentiate isotopes will be described. Finally, the energy spectra will be presented and compared to previous measurements.

Original languageEnglish
Number of pages4
Publication statusPublished - 2011
Externally publishedYes
Event32nd International Cosmic Ray Conference, ICRC 2011 - Beijing, China
Duration: Aug 11 2011Aug 18 2011


Other32nd International Cosmic Ray Conference, ICRC 2011


  • BESS
  • BESS-polar I
  • Balloon-borne experiment
  • Cosmic-rays
  • Helium isotopes

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


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