CREAM: Results, Implications and Outlook

The Cosmic Ray Energetics And Mass (CREAM) balloon-borne experiment has accumulated ∼161 days of exposure during six successful flights over Antarctica. Energy measurements are made with a transition radiation detector and an ionization calorimeter. Charge measurements are made with timing scintillators, pixelated Si, and Cherenkov detectors to minimize the effect of backscattered particles. High energy cosmicray data were collected over a wide energy range from ∼ 1010 to ∼ 1015 eV at an average altitude of ∼ 38.5 km, with ∼ 3.9 g/cm2 atmospheric overburden. All cosmic-ray elements from protons (Z = 1) to iron nuclei (Z = 26) are separated with excellent charge resolution. Recent results from the ongoing analysis including the discrepant hardening of elemental spectra at ∼ 200 GeV/n are presented and their implications on cosmic-ray origin, acceleration and propagation are discussed. The project status and plans are also presented.