Atmospheric Temperature Effect forμMesons Observed at a Depth of 846 m.w.e.

The experiment reported was a measurement of the effect of variations in atmospheric temperatures on the intensity of $\mu$ mesons observed underground at a depth of 846 m.w.e. The average energy of these particles is known to be ∼2×${10}^{11}$ ev. A total of ∼1.2×${10}^6$ coincidences, between two large trays of Geiger counters located in a salt mine, was collected over a two-year period. The correlation between variations in counting rate and simultaneous variations in effective atmospheric temperature was analyzed. The effective temperature was determined from radiosonde measurements of atmospheric temperatures at pressure levels up to 20 millibars performed by a U. S. Air Force weather observation unit near the salt mine. The resulting temperature coefficient is 0.22±0.06 percent per degree and the correlation coefficient is 0.75. The results are compared with those obtained from similar measurements at 1574 m.w.e. and with the theoretical values of the temperature coefficient derived from various schemes describing the production of $\mu$ mesons with high energies.