Revised energy spectra for primary elements (H - Si) above 50 GeV from the ATIC-2 science flight

J. P. Wefel, Louisiana State University
J. H. Adams, NASA Marshall Space Flight Center
H. S. Ahn, University of Maryland, College Park
G. Bashindzhagyan, Lomonosov Moscow State University
J. Chang, Purple Mountain Observatory Chinese Academy of Sciences
M. Christl, NASA Marshall Space Flight Center
A. R. Fazely, Southern University and A&M College
O. Ganel, University of Maryland, College Park
R. M. Gunashingha, Southern University and A&M College
T. G. Guzik, Louisiana State University
J. B. Isbert, Louisiana State University
K. C. Kim, University of Maryland, College Park
E. N. Kouznetsov, Lomonosov Moscow State University
M. Panasyuk, Lomonosov Moscow State University
A. Panov, Lomonosov Moscow State University
W. K.H. Schmidt, Max Planck Institute for Solar System Research
E. S. Seo, University of Maryland, College Park
N. Sokolskaya, Lomonosov Moscow State University
J. Watts, NASA Marshall Space Flight Center
J. Wu, University of Maryland, College Park
V. I. Zatsepin, Lomonosov Moscow State University

Abstract

The Advanced Thin Ionization Calorimeter (ATIC) long duration balloon experiment had a successful science flight (12/02 -1/03) accumulating 18 days of data during a single circumnavigation of Antarctica. ATIC measures the energy spectra of elements from H to Fe in primary cosmic rays using a fully active Bismuth Germanate calorimeter preceded by a carbon target, with embedded scintillator hodoscopes, and a silicon matrix charge detector at the top. Preliminary results from ATIC have been reported in previous conferences. The revised results reported here are derived from a new analysis of the data with improved charge resolution, lower background and revised energy calibration. The raw energy deposit spectra are de-convolved into primary energy spectra and extrapolated to the top of the atmosphere. We compare these revised results to previous data.