Nuclear Disintegrations Induced by<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>μ</mml:mi></mml:math>-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, $\ensuremath{\mu}$-mesons are the particles causing either directly or indirectly most of the events recorded at depths greater than \ensuremath{\sim}10 m water. The cross section of $\ensuremath{\mu}$-mesons for nuclear interactions is found to be \ensuremath{\sim}1\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}29}$ ${\mathrm{cm}}^{2}$/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 $\ensuremath{\mu}$-mesons and $N$-component at sea level are given.