Approaching the Spectral Knee in High Energy Cosmic Rays with CREAM

The balloon-borne Cosmic Ray Energetics And Mass (CREAM) experiment flew for the third time in Antarctica between 19 December 2007 and 16 January 2008. This ∼ 29-day flight resulted in an accumulation of almost 100 days of exposure for the CREAM payload. The instrument included double layers of finely segmented Silicon detectors and an imaging Cherenkov Camera for charge measurements. A finely segmented tungsten-scintillator fiber ionization calorimeter was used for energy measurements. Energy spectra of cosmic ray particles for 1 < Z < 26 were measured at the top of atmosphere with excellent charge and energy resolution. CREAM extends direct measurements of cosmic-ray composition to energies where ground-based air shower measurements are possible, thereby providing calibration for those indirect measurements. The instrument performance during the flight and results from the ongoing data analysis are presented. The project status, including preparations for the next flight and results from the beam test carried out at CERN in 2007, are also be reported. © 2009 The Physical Society of Japan