Measurement of the cosmic-ray antiproton spectrum in the range 0.12 to 0.4 GeV with BESS-Polar II

K. Sakai, J. K. Abe, H. Fuke, S. Haino, T. Hams, M. Hasegawa, K. C. Kim, M. H. Lee, Y. Makida, J. W. Mitchell, J. Nishimura, M. Nozaki, R. Orito, J. F. Ormes, N. Picot-Clemente, M. Sasaki, E. S. Seo, R. E. Streitmatter, J. Suzuki, K. TanakaN. Thakur, A. Yamamoto, T. Yoshida, K. Yoshimura

Research output: Contribution to journalConference article

Abstract

The energy spectra of cosmic-ray antiprotons and protons near solar minimum were precisely measured with BESS-Polar II (Balloon-borne Experiment with a Superconducting Spectrometer) during a long-duration flight over Antarctica in December 2007 and January 2008. The upper-TOF (UTOF) and lower-TOF (LTOF) scintillator hodoscopes measure the charge and velocity of incident particles. A thin plastic scintillator middle-TOF (MTOF) hodoscope is installed on the lower surface of the magnet bore to measure low-energy particles that cannot reach the LTOF. The MTOF further lowers the threshold energy to about 120 MeV for antiproton or proton measurements. We report absolute spectra of the cosmic-ray antiproton in the range 0.12 to 0.4 GeV and the antiproton/proton ratio calculated with UTOF-MTOF trigger events. These new results are independent of the UTOF-LTOF triggered antiproton spectrum published in 2012 and proton spectrum published in 2016.

Original languageEnglish
JournalProceedings of Science
Publication statusPublished - 2017
Event35th International Cosmic Ray Conference, ICRC 2017 - Bexco, Busan, Korea, Republic of
Duration: Jul 10 2017Jul 20 2017

ASJC Scopus subject areas

  • General

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    Sakai, K., Abe, J. K., Fuke, H., Haino, S., Hams, T., Hasegawa, M., Kim, K. C., Lee, M. H., Makida, Y., Mitchell, J. W., Nishimura, J., Nozaki, M., Orito, R., Ormes, J. F., Picot-Clemente, N., Sasaki, M., Seo, E. S., Streitmatter, R. E., Suzuki, J., ... Yoshimura, K. (2017). Measurement of the cosmic-ray antiproton spectrum in the range 0.12 to 0.4 GeV with BESS-Polar II. Proceedings of Science.