Evidence for the possible emission of high-energy neutrons from the Sun

Abstract

From a balloon flight made from Hyderabad, India (geographic latitude 17.3°N and longitude 78.5°E and geomagnetic vertical cutoff rigidity 16.9 Gv), on March 23, 1962, the flux of neutrons in the energy region 4–160 Mev has been determined by making observations on tracks of protons recoiling from elastic collisions of neutrons with hydrogen nuclei present in nuclear emulsions that were freshly coated for this experiment. An analysis of the data obtained from these emulsions and other control emulsions has provided evidence for the possible emission of neutrons from the sun in the energy interval of 20–160 Mev; the flux obtained is 148±60 neutrons/m2 sec. The balloon flight was made on a day when the sun-spot number was at its peak of the 27-day variation and 6 hours after an optical flare of magnitude 3, which produced no particle intensity variations or geophysical effects at the earth.