Čerenkov Scintillation Counter Measurements Relating to the Isotopic Composition of Helium Nuclei in the Primary Cosmic Radiation

Abstract

A balloon-borne scintillation-scintillation Čerenkov telescope has been used to measure the spectrum and geomagnetic cutoff-transmission effects on the low-energy proton and helium components in the primary cosmic radiation. Differences are found in the cutoff effects (assumed to be rigidity-dependent) of these two components in flights at closely adjacent latitudes. It is shown that these differences can be related to the presence of ${\mathrm{He}}^3$ in the primary radiation. The ratio (${\mathrm{He}}^3$/${\mathrm{He}}^3$+${\mathrm{He}}^4$) is deduced to be 0.30±0.07, essentially independent of energy in the range 120-300 MeV/nucleon. This result is compared with other measurements and some implications regarding the production of the ${\mathrm{He}}^3$ nuclei are discussed.