Neutrons Produced in the Atmosphere by the Cosmic Radiations

The distribution of disintegration product neutrons in the atmosphere has been measured from the geomagnetic equator to 65°N and up to ∼220 g-${\mathrm{cm}}^{-2\mathrm{}}$ air. The measured exponential absorption of the neutron producing radiations in the equilibrium portion of the atmosphere is: $L\left(0\mathrm{}°\right)=212\mathrm{}$, $L\left(19\mathrm{}°\right)=206\mathrm{}$, $L\left(40\mathrm{}°\right)=181\mathrm{}$, $L\left(53\mathrm{}°\right)=157\mathrm{}$, $L\left(65\mathrm{}°\right)=157\mathrm{}$ g-${\mathrm{cm}}^{-2\mathrm{}}$. It is shown that the neutron component has the largest latitude effect of any known secondary component in the cosmic rays and that the neutrons are part of a low energy nucleonic component in the atmosphere. The yield of neutrons per incident primary particle in an air column one ${\mathrm{cm}}^2$ area extending through the atmosphere has been calculated at various latitudes. The yield increases by 400 percent between 0° and 55°N. The slow neutron absorption in air at the geomagnetic equator under 312 g-${\mathrm{cm}}^{-2\mathrm{}}$ air was measured. It is concluded that nucleon collision chains in the atmosphere are the principal process by which a low energy nucleonic and neutron component is produced. Measurements at high latitudes over a period of two years have shown that fluctuations and large changes of intensity of the neutron component may occur during solar and terrestrial disturbed days.