Neutron high-energy spectra at 5 mbar near the geomagnetic equator

Abstract

Ilford G5 emulsions were exposed at 4 and 6 mbar on balloon flights from Hyderabad, India, at λ = 7.8°N. Atmospheric neutrons in the energy range ∼8–200 MeV are studied. Two independent parameters are used: knock‐on protons covering the neutron energy range 8–160 MeV and low‐energy evaporation stars for ∼40–200 MeV. Neutron fluxes and up/down ratios near 5 mbar are given for different energy ranges. Neutron energy spectra at 5 mbar and the energy range 15–160 MeV are given, and these spectra show a structure. A power law of the form AE−n is fitted to the experimental data, and values of the spectral index n are given. Neutron energy spectra at 5 mbar for the up and down components as well as for the total are presented. These results are compared with theoretical and experimental results reported by other workers. Our albedo neutron results are in good agreement with the published results and strongly support the Crand theory.