Proton and helium spectra from the CREAM-III flight
- Y. S. Yoond(Author),
- H. S. Ahnd(Author),
- T. Andersona(Author),
- A. Barrauh(Author),
- R. Bazer-Bachi(Author),
- J. J. Beattyc(Author)
- aPenn State University,
- bUniversidad Nacional Autónoma de México,
- cOhio State University,
- dUniversity of Maryland, College Park,
- eNASA Goddard Space Flight Center,
- fNorthern Kentucky University
Abstract
The primary cosmic-ray elemental spectra have been measured by the balloon-borne Cosmic Ray Energetics And Mass (CREAM) instrument. CREAM has flown six times over Antarctica since 2004. The CREAM-III payload, comprised of a tungsten/scintillating fiber calorimeter, silicon charge detector (SCD), Cherenkov camera, and timing charge detector, flew for 29 days during the 2007-2008 Antarctic season. The flight accumulated significantly more calorimeter data than the two previous flights at lower energies due to a lower electronics noise level of the calorimeter and improved read-out electronics with 16-bit analog-digital conversion. The SCD provided better resolution with reduced electronics noise than for the CREAM-I flight data. In addition, two silicon layers in the SCD provided two independent charge measurements. Charge identification with the two independent charge measurements is included in this analysis, as are estimates of efficiencies, backgrounds, and energy conversion using updated Monte Carlo (MC) simulations (with the CREAM-III flight detector configuration). These refinements had not been included in previously reported results. Proton and helium energy spectra from CREAM-III flight are presented.