AbstractsPhysics

Special photographic emulsions developed to record the tracks of charged particles hâve been exposed to cosmic rays at high altitudes by being carried in aircraft on trans-Atlantic flights. Total exposure times of more than 200 hours above 10,000 feet, with more than half being above 15*000 feet, were achieved, Microscopic examination of the plates disclosed a large number of nuclear disintegrations produced by cosmic rays. Detailed study of thèse disintegrations revealed several types not previously reported. Mesons were observed which produced at the end of their range a single proton, a single alpha particle, or one or more of each, and in one case, a secondary meson. Mesons were found among the particles of nuclear disintegrations. Other phenomena included the fast neutron disintegration of boron, the éjection of an alpha and a proton from nuclei, a "star" of 26 particles, and proton tracks with energies greater than 40 mev.