12-20 July 2017
BEXCO
Asia/Seoul timezone
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Contribution

BEXCO - Room F(201/202/203/204)

[SH121] Energy Spectra of Cosmic-ray Elements near Earth: New Results from NASA's Advanced Composition Explorer

Speakers

  • M. E. WIEDENBECK

Primary authors

  • M. E. WIEDENBECK (Jet Propulsion Laboratory, California Institute of Technology, USA)

Co-authors

Description

For almost 20 years, the Cosmic Ray Isotope Spectrometer (CRIS) on ACE has been providing high-statistics, near-Earth measurements of cosmic-ray energy spectra below the intensity maximum, which occurs at several hundred MeV/nucleon. These data, which are derived from measurements of nuclei that stop in the CRIS instrument, are a valuable resource for studying the time dependence of solar modulation, but such analyses depend on some knowledge of the spectra at higher energies where modulation effects are less significant. Previously, we have used the high-energy spectra for elements between B and Ni that were obtained from the HEAO-C2 instrument, which operated in the early 1980s, for this purpose. In order to better constrain spectral shapes in the region near the intensity maximum, we have developed a new analysis technique to identify elements and infer energies for particles that completely penetrate the CRIS instrument. We will discuss this new analysis and present ACE/CRIS energy spectra over an extended range that combine both stopping- and penetrating-particle data. Those spectra will be used to infer the time variation of the solar modulation level over nearly two full solar cycles and to compare with other cosmic-ray heavy-element spectra that have been published in recent years.