Atmospheric neutron flux measurements

The energetic neutron flux at atmospheric depths from 160 to 300 g/cm−2 has been measured over latitudes extending from the equator to 55°N geomagnetic. Comparison of data with previous measurements indicates that at the time of these measurements the neutron spectrum was steeper than that determined by Hess et al. for neutrons of E > 60 Mev but was of the same form for E < 10 Mev. An anomalous increase in the flux of neutrons of E > 60 Mev was detected on July 21, 1962, over a region from 50° to 55°N geomagnetic. The increase is possibly attributable to a dumping of protons temporarily trapped in the slot between the inner and outer Van Allen zones.