TY - GEN
T1 - Short-term variations in cosmic ray proton fluxes from BESS-polar I
AU - FOR THE BESS-POLAR COLLABORATION.
AU - Thakur, N.
AU - Abe, K.
AU - Fuke, H.
AU - Haino, S.
AU - Hams, T.
AU - Itazaki, A.
AU - Kim, K. C.
AU - Kumazawa, T.
AU - Lee, M. H.
AU - Makida, Y.
AU - Matsuda, S.
AU - Matsumoto, K.
AU - Mitchell, J. W.
AU - Myers, Z.
AU - Nishimura, J.
AU - Nozaki, M.
AU - Orito, R.
AU - Ormes, J. F.
AU - Sasaki, M.
AU - Seo, E. S.
AU - Shikaze, Y.
AU - Streitmatter, R. E.
AU - Suzuki, J.
AU - Takasugi, Y.
AU - Takeuchi, K.
AU - Tanaka, K.
AU - Yamagami, T.
AU - Yamamoto, A.
AU - Yoshida, T.
AU - Yoshimura, K.
N1 - Funding Information:
uous encouragement in this US-Japan cooperative project. Sincere thanks are expressed to the NASA Balloon Program Office at GSFC/WFF and CSBF for their experienced support. They also thank ISAS/JAXA and KEK for their continuous support and encouragement. Special thanks go to the National Science Foundation (NSF), U.S.A., and Raytheon Polar Service Company for their professional support in U.S.A. and in Antarctica. The BESS-Polar experiment, a Japan-U.S. collaboration, is supported by a KAK-ENHI(13001004 and 18104006) in Japan, and by NASA in U.S.A.
Publisher Copyright:
© 2013 Sociedade Brasileira de Fisica. All Rights Reserved.
PY - 2013
Y1 - 2013
N2 - BESS (Balloon-borne Experiment with a Superconducting Spectrometer) had its first circumpolar flight from Williams Field near McMurdo Station, Antarctica from Dec. 13 to 21, 2004. We have analyzed proton fluxes for this flight to study short-term variations in their intensities. Throughout a balloon flight, altitude varies, and, as a result, the atmospheric overburden changes. Precise determination of primary particle fluxes at the top of Earth’s atmosphere, requires a detailed correction for the effects of atmosphere on the fluxes observed by the detector. We carried out a careful analysis of BESS-Polar I data by dividing the whole flight data set into intervals of 4 hours. Then primary proton fluxes were individually determined for each of these time intervals after applying individual atmospheric corrections for each of these 4-hour intervals. Our sub-1% precision measurements of BESS Polar-I proton relative fluxes exhibit short-term variations after all instrumental effects are removed. The time progression of proton flux has two main features; a rising flux at the beginning of the flight, followed by quasi-periodic variation. Although the Sun was primarily quiet, arrival of a high-speed solar wind stream, enhancement of the interplanetary magnetic field, and a high energy multiple eruption solar energetic particle event occurred around this flight. In addition, the BESS-Polar I flight commenced during the recovery phase of a Forbush decrease. We present BESS-Polar I proton flux progression as a function of energy between 0.1 - 100.0 GeV and suggest possible physical interpretations of the observed variations in relation with interplanetary structures in the near-Earth space.
AB - BESS (Balloon-borne Experiment with a Superconducting Spectrometer) had its first circumpolar flight from Williams Field near McMurdo Station, Antarctica from Dec. 13 to 21, 2004. We have analyzed proton fluxes for this flight to study short-term variations in their intensities. Throughout a balloon flight, altitude varies, and, as a result, the atmospheric overburden changes. Precise determination of primary particle fluxes at the top of Earth’s atmosphere, requires a detailed correction for the effects of atmosphere on the fluxes observed by the detector. We carried out a careful analysis of BESS-Polar I data by dividing the whole flight data set into intervals of 4 hours. Then primary proton fluxes were individually determined for each of these time intervals after applying individual atmospheric corrections for each of these 4-hour intervals. Our sub-1% precision measurements of BESS Polar-I proton relative fluxes exhibit short-term variations after all instrumental effects are removed. The time progression of proton flux has two main features; a rising flux at the beginning of the flight, followed by quasi-periodic variation. Although the Sun was primarily quiet, arrival of a high-speed solar wind stream, enhancement of the interplanetary magnetic field, and a high energy multiple eruption solar energetic particle event occurred around this flight. In addition, the BESS-Polar I flight commenced during the recovery phase of a Forbush decrease. We present BESS-Polar I proton flux progression as a function of energy between 0.1 - 100.0 GeV and suggest possible physical interpretations of the observed variations in relation with interplanetary structures in the near-Earth space.
KW - BESS-Polar I
KW - CIR
KW - Diurnal variations
KW - Proton fluxes
KW - Short-term variations
UR - http://www.scopus.com/inward/record.url?scp=85052473366&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85052473366&partnerID=8YFLogxK
M3 - Conference contribution
AN - SCOPUS:85052473366
T3 - Proceedings of the 33rd International Cosmic Rays Conference, ICRC 2013
BT - Proceedings of the 33rd International Cosmic Rays Conference, ICRC 2013
PB - Sociedade Brasileira de Fisica
T2 - 33rd International Cosmic Rays Conference, ICRC 2013
Y2 - 2 July 2013 through 9 July 2013
ER -