Abstract
Observations of cosmic-ray helium energy spectra provide important constraints on cosmic ray origin and propagation. However, helium intensities measured at Earth are affected by solar modulation, especially below several GeV/nucleon. Observations of helium intensities over a solar cycle are important for understanding how solar modulation affects galactic cosmic ray intensities and for separating the contributions of anomalous and galactic cosmic rays. The Cosmic Ray Isotope Spectrometer (CRIS) on ACE has been measuring cosmic ray isotopes, including helium, since 1997 with high statistical precision. We present helium elemental intensities between ∼10 to ∼100 MeV/nucleon from the Solar Isotope Spectrometer (SIS) and CRIS observations over a solar cycle and compare these results with the observations from other satellite and balloon-borne instruments, and with GCR transport and solar modulation models.
Original language | English (US) |
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Pages | 813-816 |
Number of pages | 4 |
State | Published - 2007 |
Event | 30th International Cosmic Ray Conference, ICRC 2007 - Merida, Yucatan, Mexico Duration: Jul 3 2007 → Jul 11 2007 |
Other
Other | 30th International Cosmic Ray Conference, ICRC 2007 |
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Country/Territory | Mexico |
City | Merida, Yucatan |
Period | 7/3/07 → 7/11/07 |
ASJC Scopus subject areas
- Nuclear and High Energy Physics