Characteristics and fine structure of the large cosmic-ray fluctuations in November 1960

Measurements obtained at Deep River, Canada, from two large neutron monitors, and at Cambridge, Massachusetts, from a high counting rate meson monitor, during the solar cosmic-ray injections of November 12 and 15, 1960, are reported. In addition, rate-meter pen traces of the neutron increases and a magnetometer trace of H, obtained at Deep River, are reproduced. The solar cosmic-ray increase of November 12 appears to be unique in that while it was in progress a sharp Forbush decrease happened to occur as shown by the MIT meson intensity. Half an hour before the onset of the Forbush decrease, and coincident with a conspicuous increase of H, the intensity of the solar cosmic radiation doubled and then exhibited strong rapid oscillations. We advance arguments that the changes of intensity of the solar cosmic rays observed at high latitudes at the time of the magnetic disturbance and Forbush decrease are due to the earth sampling solar cosmic rays trapped in the gas cloud responsible for these latter effects. The events of November 12 and 15 are both shown to be in agreement with a recent model for the magnetic fields in the inner solar system. At the time of the solar cosmic-ray increase of November 15, the earth was already inside a trapping region, and periodic oscillations of the solar cosmic-ray intensity were observed lasting for about 2 hours. It is suggested that these oscillations may be closely connected with the storage mechanism.