Stable beams  How to Proceed  Neutrino detectors

Cosmic ray observations

The largest European CR activities are (from north to south): the KASCADE experiment at Karlsruhe (mainly aiming at solving the long standing question of the chemical composition above 10¹⁴ eV by performing high resolution large scale calorimetry, combined with precise electron and muon measurements in a scintillator matrix), the CAT detector, a recently started high performance air Cerenkov telescope in the French Pyrenees, the EAS-TOP installation on top of the Gran Sasso Laboratory, and the HEGRA experiment on La Palma, a combination of 6 air Cerenkov telescopes, a scintillator matrix, a wide angle Cerenkov array and Geiger towers for muon detection and some calorimetry. In addition, a British group operates large Cerenkov telescopes in Australia since 1979. Some groups participate in international activities, the most successful being an Irish-UK collaboration with the Harvard-Smithsonian groups operating the 10 m WHIPPLE air Cerenkov telescope. The low expected flux of >10²⁰ eV CR's (1 particle/100 square km/year) requires large detectors. Therefore, a large world-wide collaboration with a significant European participation is studying the construction of two 2500 km² detectors (one on the southern hemisphere in Argentina, one on the northern hemisphere in Utah), the so-called AUGER-project. Gamma-astronomy promises fast and rich results and quite a few new activities are under discussion. Solar farms open a door for quick and cost-effective experiments in the energy range below 3 $\times 10^{11}$ eV but with modest gamma/hadron separation and also relatively small collection area (Celeste in the French Pyrenees, Graal at CESA I in Spain). The most ambitious plan is to build a 17 m Cerenkov telescope (MAGIC). This telescope, involving many new technologies, allows to explore the last 'white spot' in the energy scale between 20 GeV and 300 GeV with high efficiency. One expects to find between 100 and 1000 new gamma sources. These next generation experiments in earthbound gamma-ray astronomy will overlap with the next generation satellites and permit multiwavelength observations from radiowaves up to energies of at least 10¹⁴ eV.