Absolute Cosmic-Ray Ionization in the Atmosphere at Balloon Altitudes

Citation

Johnston, Alan Robert (1956) Absolute Cosmic-Ray Ionization in the Atmosphere at Balloon Altitudes. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/QZ0V-ND39. https://resolver.caltech.edu/CaltechETD:etd-03242004-144425

Abstract

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. A determination of absolute cosmic-ray ionization at balloon altitudes has been made using an integrating ionization chamber. It was filled to 1 atm with argon, and was calibrated to give ionization in the argon. The ionization produced by nuclear particles in 5 charge groups, electrons, [...], and stars was computed between 10 and 140 gm cm[superscript -2] to form a basis for estimating the wall effect and recombination. The important corrections for wall effect were from stars and low-energy electrons. A 1.4 [+ or -] 1.7% effect was estimated, the ionization being less without the wall. Recombination was investigated and found negligible in the 1-atm chamber. The resulting ionization in argon was converted to ionization in air on the basis of the relative ionization by charged particles in the two gases. The relative ionization of 340-Mev protons, from cyclotron experiments, was corrected by energy loss theory to give the relative ionization of particles with cosmic-ray velocities. The final result was that ionization values obtained with the existing calibration should be multiplied by 1.049 [+ or -] 0.031 to obtain the correct ionization, from 7 - 140 gm cm[superscript -2] depth. The unit used is ions cm[superscript -3] sec[superscript -1] atm[superscript -1] of air at 20[degrees]C. Further experiments were suggested.

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