Production of Mesotrons up to 30,000 Feet at a Magnetic Latitude of 22° North

The production of mesotrons by non-ionizing radiation in a lead thickness of 2 cm was measured in an airplane at a magnetic latitude of 22° North. In general the results are in agreement with those obtained by Schein, Jesse, and Wollan. In addition it was found that mesotrons passing through 8 cm of lead exhibit in the intensity $\mathrm{vs}$. altitude curve a marked hump in the neighborhood of a pressure of 530 millibars.