On μ Mesons in Extensive Air Showers at Sea Level

抄録

The lateral distribution of μ mesons in extensive air showers (EAS), their energy spectrum and the relation between the total number of μ mesons and that of charged particles have been studied utilizing the accurate informations of EAS. The total number of μ mesons in each EAS fluctuates over a range of one order of magnitude in a given size. The lateral distribution of μ mesons does not seem to fluctuate in spite of the fluctuation of the starting point of EAS.
The experimental results have been compared with the calculation based on a simple model of development of EAS. It is concluded that the attenuation length of the nuclear active particles which correspond to μ mensons with the average energy of about 10 Bev is (200∼250) g cm⁻² in air.