High energy cosmic rays composition measurements by CREAM experiment

The balloon-borne experiment Cosmic Ray Energetics And Mass (CREAM) investigates very high energy (10e10 to 10e15 eV) cosmic rays over the elemental range from protons to iron. This energy range offers promising prospects for answering fundamental questions related with the source, acceleration mechanism and propagation conditions of the cosmic-ray flux. This should also help constraining the astrophysical parameters mandatory to search for dark-matter signals in the GeV range. The first CREAM flight was launched from the McMurdo Station, Antarctica, aboard a NASA research balloon on December 16, 2004. Floating for nearly 42 days at altitudes between 36 and 39 km, CREAM collected over 4 x 10e7 events. CREAM-II was launched on December 16, 2005 and flew for 28 days. The preliminary analysis already show some very interesting results emerging from this set of data. The CREAM III flight is scheduled to fly next winter 2007 with, among others instrumental improvements, a Cherenkov imager (RICH) detector, providing individual separation of nuclear cosmic-ray elements through the whole range of interest, in account of its excellent charge resolution over this range. This upgrade should improve significantly the instrument performances, especially in the high mass range of the detected particles