Tibet AS-gamma Experiment

Present status of our research activities:

Measurement of the energy spectrum of primary cosmic rays in the "knee" region (3x1014eV-2x1016eV):

We made a precise measurement of the energy spectrum of primary cosmic rays in the "knee" region (Fig. 13).
On the other hand, the burst detectors and emulsion chambers set up at the center of the air shower array preferentially detect high-energy particles in an air shower event. We can classify primary cosmic-ray nuclei into several groups according to the energy and spatial distributions of the high-energy component of an air shower event detected with the burst detectors and emulsion chambers. We also measure the total energy of the event by the air shower array. Therefore, simultaneous observation of an air shower event by the burst detectors, emulsion chambers and air shower array gives us the energy spectrum of each group in primary cosmic rays (Fig. 13). The chemical composition in the ''knee'' region is a crucial key to clarify the mechanism how cosmic rays are generated, accelerated and propagate to the Earth.

Fig. 13
Fig. 13 Energy spectrum of primary cosmic rays in the ''knee'' region.