On the Seasonal and the Atmospheric Temperature Effect in Cosmic Radiation

By analysis of the observations of the cosmic-ray ionization on the Hafelekar (2300 meters above sea level, 48 North geomagnetic lat, ) during five years the existence of a seasonal variation with an amplitude of &0.9 percent has been proved. Reduction of the monthly means to the annual mean temperature diminishes the amplitude of the 12-month wave to one-half without eliminating it. This agrees with Vallarta and Godart's interpretation of the seasonal effect:. A very marked seasonal change in the temperature coefficient of the cosmic radiation has been found, recurring every year. In winter the coefficients are about —0.12, in summer —0.055 percent per degree centigrade. The correlation between temperature and ionization is in winter twice as great as in summer. Derivation of the temperature coefficient from hourly observations gives too low absolute values because of the diurnal changes involved. With unscreened ionization chambers and also with coincidence counter arrangements (triangle position), smaller temperature coefficients are found, which become positive in summer. It is thus not possible to explain the normal negative temperature effect of cosmic radiation completely on the basis of the mesotron disintegration hypothesis.