Time Variation of Primary Heavy Nuclei in Cosmic Radiation

The time variation of heavy nuclei in the primary cosmic radiation was investigated by using the method of a moving-plate mechanism which was flown to an altitude of 100 000 feet by a Skyhook balloon. The results obtained clearly indicate a time variation of primary heavy nuclei $Z\gtrsim 10$. The variation is characterized by its maximum at around 9:00 a.m., having an amplitude of 34±7% at the maximum. Comparisons are made with other experimental data on the same subject and also with the neutron intensity variation on the same day at Climax, Colorado. Possible consequences of this rather large fluctuation of the primary heavy nuclei are discussed.