Fluxes and energy spectra of secondary neutrons with energies >20 MeV as measured by the MIR orbital station, the SALYUT-7-KOSMOS-1686 orbital complex, and the KORONAS-I satellite:: Comparison of experimental data and model calculations

Data on fluxes and spectra of neutrons with E-n > 20 MeV under the Earth's radiation belts obtained during experiments aboard the MIR orbital station, the SALYUT-7-KOSMOS-1686 orbital complex, and the KORONAS-I satellite are presented. Instruments based on the CsI(T1) scintillation crystal were used in these experiments for detecting the neutrons. Moreover, the method of particle discrimination by the pulse shape in CsI(Tl) allowed us to detect neutrons against an intensive gamma-ray background. Latitude dependences of neutron fluxes and their spectra were obtained aboard heavy spacecraft, the experimental data coinciding rather well with model calculations. Additionally, it was shown that neutron fluxes depend on the spacecraft mass and can be approximated by a linear function in a wide range of masses.