Atmospheric Temperature Effect for Mesons Far Underground

A continuation of measurements previously reported has led to verification of the positive temperature effect for μ mesons detected at 1574 m.w.e. underground, which are created in the atmosphere with an average energy of about 8×{}10¹¹ ev. The new result for the temperature coefficient at this depth is 0.33±{}0.13 percent per deg C; and this value combined with the previous measurement yields an average of 0.46±{}0.11 percent per degree, agreeing with the value expected if the π-μ decay process is responsible for all, or most, of these μ mesons.