OBSERVATIONS ON STARS AND HEAVY PRIMARIES RECORDED IN EMULSIONS FLOWN IN VIKING ROCKET NO. 9

Abstract

Methods for the preparation of fresh nuclear emulsions for use in the study of cosmic radiation by rocket exposures are described. Shattering and mechanical damage is minimized by substituting transparent plastics for the glass support. By casting the emulsion on a temporary microporous medium such as plaster of Paris, emulsions 2 mm. thick can be dried in about six days without appreciable loss of sensitivity. Strong, thin-walled housings for the emulsions are described. The star production rate in emulsions flown in the mesosphere to a peak altitude of 217 km. is 1180 ± 280 cc.−1 d.− 1 and is 1.45 ± 0.17 times greater than similar measurements in the stratosphere (30 km.). The augmentation of nuclear disintegrations can be accounted for by the opening up of the effective solid angle for star-producing radiation during the rocket flight. Energetic stars with three or more shower particles record with a frequency of 278 ± 30 cc.−1 d.−1, about three times greater than in a balloon flight at the same geomagnetic latitude. For large showers Ns = 6, the N/P ratio is about 0.17. The observational ratio of M to H nuclei based on a spectrum of 238 heavy primary tracks is 2.66. When corrected for fragmentation in surrounding matter this ratio is reduced to 2.5 ± 0.5. The omnidirectional flux of heavy primaries [Formula: see text] at the top of the atmosphere is 7.62 meter−2 sec.−1 sterad.−1. An analysis of the zenith angle distribution of the heavy primaries shows that the unidirectional flux is in fair agreement with geomagnetic theory for zenith angles < 60°. The directional flux for θ > 60° is about two times greater than predicted by theory.