The invention of the neutron monitor pile for the study of cosmic-ray intensity-time and energy changes began with the discovery in 1948 that the nucleonic component cascade in the atmosphere had a huge geomagnetic latitude dependence. For example, between 0 • and 60 • this dependence was a ∼ 200-400% effect-depending on altitude-thus opening the opportunity to measure the intensity changes in the arriving cosmic-ray nuclei down to ∼1-2 GeV nucl −1 for the first time. In these measurements the fast (high energy) neutron intensity was shown to be a surrogate for the nuclear cascade intensity in the atmosphere. The development of the neutron monitor in 1948-1951 and the first geomagnetic latitude network will be discussed. Among its early applications were: (1) to prove that there exists interplanetary solar modulation of galactic cosmic-rays (1952), and; (2) to provide the evidence for a dynamical heliosphere (1956). With the worldwide distribution of neutron monitor stations that are presently operating (∼ 50) many novel investigations are still to be carried out, especially in collaborations with spacecraft experiments.
CITATION STYLE
Simpson, J. A. (2000). The Cosmic Ray Nucleonic Component: The Invention and Scientific Uses of the Neutron Monitor (pp. 11–32). https://doi.org/10.1007/978-94-017-1187-6_2
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