Chercam: A Cherenkov Imager For The Cream Experiment

The CREAM experiment (Cosmic Ray Energetics and Mass) is dedicated to the measurement of the energy spectrum of nuclear elements in cosmic rays, over the range 10(12) to 10(15) eV. It has already begun to measure high energy cosmic rays at the frontier of the statistical limits accessible to balloon-borne experiments.(1) Measurements of the cosmic ray spectrum of nuclei from proton to iron in this energy range will provide invaluable data on cosmic ray spectral characteristics and/or abundance changes, which could be related to the acceleration limit in the shock front of supernovae. The individual elements separation, which is a key feature of CREAM, requires instruments with strong identification capabilities. A proximity focused type of Cherenkov imager, CHERCAM (CHERenkov CAMera), providing both a good signature of downgoing Z = 1 particles and good single element separation through the whole range of nuclear charges considered, has been developed and will be part of the third CREAM flight in December 2007. After a brief introduction, the main features and test results of the CHERCAM are being summarized.