KASCADE

KASCADE (KArlsruhe Shower Core and Array Detector) was a large-scale air shower experiment located at the Karlsruhe Institute of Technology (KIT) in Germany. Its primary scientific goal was the study of the origin, composition, and energy spectrum of primary cosmic rays in the energy range from approximately 10¹⁴ eV to 10¹⁸ eV. KASCADE operated from 1996 to 2012.

The experiment consisted of a central detector, the KASCADE calorimeter, and an array of 252 detector stations spread over an area of 200 x 200 square meters. The array detected the electromagnetic component of air showers (electrons, positrons, and photons), while the central calorimeter was designed to measure the hadronic component (protons, neutrons, and pions).

By simultaneously measuring the electron and muon numbers in the air showers, KASCADE was able to provide information on the mass composition of primary cosmic rays. The experiment contributed significantly to understanding the "knee" in the cosmic ray energy spectrum, a break in the power-law distribution around 3 x 10¹⁵ eV. The knee is believed to be related to the maximum energy to which galactic accelerators, such as supernova remnants, can accelerate cosmic rays.

Data from KASCADE have been used to test different models of high-energy hadronic interactions, which are essential for interpreting air shower measurements. The experiment also provided important inputs for the development of more advanced air shower experiments like KASCADE-Grande and the Pierre Auger Observatory. KASCADE-Grande, which extended the area of the original KASCADE array, studied cosmic rays at even higher energies, up to 10¹⁸ eV.