Cosmic Ray Planetary Surveys on Ships, Trains, Tracks, Planes, Balloons, and Satellites

Within the framework of the project “Japanese Antarctic Research Expedition,” measurements were taken of CR intensities (nucleonic – by a Simpson-type neutron monitor described in Simpson (1951), and muonic – by a Neher-type ionization chamber which was used in previous Japanese expeditions by Sekido et al., 1943) on the expedition ship Soya along a constant route between Japan and Antarctica (see Fig. 4.1), during five surveys between 1956 and 1962 (Kodama, 1960; Fukushima et al., 1963).

This route passes through two intense geomagnetic anomalies around Singapore and Cape Town. Each survey started in October or November and finished the following April or May every year excepting 1957/58. The period of these latitude surveys corresponds to periods from the maximum of solar activity to near the minimum. Importantly, the obtained data are useful for investigation of threshold rigidity distribution, for determining the position of the CR equator, for estimation of coupling functions for neutron and muon components, as well as for research of longterm CR modulation depending on particle rigidities. In Fig. 4.2 voyage courses are shown along which CR measurements were carried out and in Table 4.1 gives short information on these CR latitude surveys for the period 1936–1957.