The Structure of the Solar Cycle Maximum Phase in the Galactic Cosmic Ray 11-year Variation

The maximum phase in the solar cycle variation of the galactic cosmic ray (GCR) intensity, J(t), is considered using neutron monitor, balloon and spacecraft data for the last five solar cycles (Nos. 19-23). For all time series considered the double peak structure (DPS) with the gap between the peaks is observed in the GCR modulation, M(t)=[J(t₀)-J(t)]/J(t₀), which proves that M belongs to a wide class of solar and heliospheric parameters demonstrating a so called Gnevyshev Gap (GG) effect. The start of the GG-effect in the cosmic ray modulation agrees closely with a change in the energy dependence of the cosmic ray modulation (the so called energy hysteresis). In recent years two hypotheses were formed about the nature of the GG-effect. One view (rooting in the pioneer work of M.N. Gnevyshev) holds that the DPS is inherent in the maximum phase of a solar cycle and its two peaks are either due to specific for each peak processes on the Sun or the results of some attenuation (Gnevyshev Gap) in the solar activity. The latter may be probably associated with the reversal of the high-latitude heliomagnetic field. The other view suggests that there is no particular difference between the sub-peaks inside the 11-year cycle, the DPS just being the result of the superposition of two quasi-oscillating processes in the solar activity with the characteristic time scales of 11 years and 1-3 years. In this paper we are trying to choose between the above hypotheses for the GCR modulation considering the dependence of the details of its DPS on the particle energy and on the heliocentric distance.