Čerenkov Counter Measurement of Multiply Charged Cosmic Rays

Measurements have been made on the charge spectrum of cosmic rays at geomagnetic latitude 41^∘{}. The value 88±{}8 particles/m² sec sterad was found for the primary alpha-particle flux. For the flux of nuclei with $6<~Z<~8$ the value 7.4±{}1.7 particles/m² sec sterad was found, and for the $Z>~9$ flux, the value 4±{}2. It is most probable that all of the Li, Be, B nuclei observed were secondary. The experiment sets an upper limit 0.25 on the abundance of primary Li, Be, B relative to the medium elements ($6<~Z<~10$).The data were obtained during balloon flights at a level of 16 g/cm². Events selected by a Geiger counter telescope were measured with a {C} {C}{}erenkov detector, and a record was kept of the pulse heights. When the pulse was greater than two relativistic protons would produce, a cloud chamber above the {C} {C}{}erenkov detector was triggered. In that way 394 events were photographed. As often as not, the photographs showed the track of a multiply charged particle traversing the telescope unaccompanied. The corresponding pulse height then served to determine the particle's charge.