Chemische Zusammensetzung der kosmischen Strahlung niederenergetischer Teilchen vonZ=12 bisZ=28, gemessen in Plastikdetektoren

Abstract

Results of a balloon flight experiment flown from Fort Churchill, Canada, at 1.8 g/cm2 for about 10 hours in 1968 are presented. The study was made using Lexan polycarbonate plastic sheets as a particle detector. The analysis of the flux and the charge composition is based on the measurement of 313 stopping particles from Mg to Ni with energies between 150 and 400 MeV/Nucl. The identification of the tracks of the particles is achieved using the restricted energy loss criterion. The flux is corrected for scanning and detector efficiency corresponding to their charge. We are able to measure the charge of a particle with an accuracy of ±0.3 charge units in the region of the iron peak. This accuracy depends on the detailed study of the cone length versus residual range. The evenZ to oddZ ratio for chargesZ≧20 is 3. We have measured the ratios of Mn/Fe=0.34, Cr/Fe=0.42 and Ca+Sc+Ti/Fe=1.05. From these measured charge ratios a thickness of (3±1) g/cm2 interstellar matter can be deduced.