Earth albedo and solar neutrons.

Abstract

Abstract : The measurements of the energy spectra and angular distributions of earth albedo neutrons from 10 to 100 MeV are reported. The measurements were made at 40 degrees N. geomagnetic latitude from a balloon at 120,000 ft. (below 4.6 g/sq. cm. of the residual atmosphere). The fluxes of upward moving neutrons at angles of 20 degrees to 70 degrees to the vertical show that the intensities of lower energy neutrons are peaked near the vertical. The distributions are integrated over angle to give a vertical energy distribution for upward moving neutrons that is flat to 50 MeV, then drops off with energy. The absolute neutron flux is of the correct strength and the energy distribution is of the correct shape for the albedo neutrons to be the source of the protons trapped in the earth's inner radiation belt. An upper limit for solar neutrons from 20 to 60 MeV for the quiet sun on September 26, 1971 is 1.0 x 10 to the minus 3rd power neutrons/sq. cm.-s with a 95% confidence limit. (Author)