Some Measurements of Atmospheric Neutrons

A series or airplane flights carrying neutron counters to an altitude of 700 g cm/sup -2/ was made at 52 20 north geomagnetic latitude in 1955. Enriched and normal BF/sub 3/ counters were covered with Cd, Sn, Pyrex, and limeglass shields. the ratios or the counting rates of the variously shielded counters are compared with the ratios calculated theoretically on a thick-shield basis using the neutron energy distribution function derived by Freese and Meyer. The neutron-production data taken by Davis and by Staker and Pyrex-glanss- envelope BF/sub 3/ counters are corrected for the absorption of neutrons by the boron in the Pyrex. The corrected neutron-production rates are recalculated to be 2.1 plus or minus 0.4 cm/sup -2/ sec/sup -1/ and 0.9 plus or minus 0.2 cm/ sup -2/ sec/sup -1/ at 54 36 and 30 24 north geomagnetic latitude, respectively, using recent values for the various neutron cross sections. These corrected rates agree, to within 5%, with the recent measurements reported by Soberman. The above energy distribution function was found, within the limited accuracy of the experiment, to describe the energy distribution of atmospheric neutrons. (auth)