Cosmic Rays at the "Knee": The KASCADE experiment (with its extension KASCADE-Grande) in Karlsruhe/Germany aims at the precise measurement of the cosmic ray energy spectrum and mass composition in the range from 1014 to 1018 eV. In this range the spectrum exhibits a marked change in its slope, the so-called knee, which is the only structure observable over many orders of magnitude in energy. Its origin seems to be a loss of light elements from the cosmic ray spectrum. The measurement of the composition gave this important information. KASCADE-Grande is a high-energy extension to see also the "second knee", expected at an energy where the heavy component of galactic cosmic rays cuts off. This experiment is running until 2009.
