Proton and Helium Spectra from the CREAM-III Flight

• Published in: The Astrophysical Journal
• Main Authors: Yoon, Y.S., Anderson, T., Barrau, A., Conklin, N.B., Coutu, S., Derome, L., Han, J.H., Jeon, J.A., Kim, K.C., Kim, M.H., Lee, H.Y., Lee, J., Lee, M.H., Lee, S.E., Link, J.T., Menchaca-Rocha, A., Mitchell, J.W., Mognet, S.I., Nutter, S., Park, I.H., Picot-Clemente, N., Putze, A., Seo, E.S., Smith, J., Wu, J.
• Other Authors: Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2017
• Subjects: charge: resolution; helium: energy spectrum; cosmic radiation: primary; helium: spectrum; helium: nucleus; methods: data analysis; cosmic rays; balloons; astroparticle physics; CREAM; statistical; calorimeter; atmosphere; silicon; 5/3; [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]; Antarctic; Antarc*
• Online Access: https://hal.archives-ouvertes.fr/hal-01554604; https://doi.org/10.3847/1538-4357/aa68e4

International audience Primary cosmic-ray elemental spectra have been measured with the balloon-borne Cosmic Ray Energetics And Mass (CREAM) experiment since 2004. The third CREAM payload (CREAM-III) flew for 29 days during the 2007–2008 Antarctic season. Energies of incident particles above 1 TeV are measured with a calorimeter. Individual elements are clearly separated with a charge resolution of ∼0.12 e (in charge units) and ∼0.14 e for protons and helium nuclei, respectively, using two layers of silicon charge detectors. The measured proton and helium energy spectra at the top of the atmosphere are harder than other existing measurements at a few tens of GeV. The relative abundance of protons to helium nuclei is 9.53 ± 0.03 for the range of 1 TeV/n to 63 TeV/n. This ratio is considerably smaller than other measurements at a few tens of GeV/n. The spectra become softer above ∼20 TeV. However, our statistical uncertainties are large at these energies and more data are needed.