Relative abundance ofHe3andHe4in cosmic rays near 10 GV

Abstract
The abundance ratio of He3 and He4 has been measured at six different atmospheric depths, from 8 g/cm2 to 23 g/cm2, employing the geomagnetic method. The ratio at the top of the atmosphere was obtained by fitting the observed six ratios. The observed ratio is consistent with the standard propagation model of cosmic rays.