Nuclear Disintegrations Induced byμ-Mesons

The absorption curve in water of the cosmic radiation producing nuclear disintegrations was obtained by recording the neutron showers occurring in an absorber surrounded by B${\mathrm{F}}_3$ counters. It was found that, while the $N$-component of the cosmic radiation is responsible for most of the disintegrations observed under the first few meters of water, $\mu$-mesons are the particles causing either directly or indirectly most of the events recorded at depths greater than ∼10 m water. The cross section of $\mu$-mesons for nuclear interactions is found to be ∼1×${10}^{-29\mathrm{}}$ ${\mathrm{cm}}^2$/nucleon at a depth of 20 m water. Estimates of the absolute intensity of the $N$-component and of the relative contribution to nuclear disintegrations by $\mu$-mesons and $N$-component at sea level are given.