One of the more interesting features of cosmic ray stars is that [Formula: see text] nuclei are ejected occasionally in the nuclear disintegrations. Such nuclei are characterized by the fact that, at the end of their range, they suffer radioactive decay (τ = 0.9 sec.) into [Formula: see text], which immediately splits up into two oppositely directed α-particles, giving what is usually referred to as a hammer track. In this investigation numerous examples have been observed of the emission of such nuclei in stars in photographic emulsions, the stars having from 2 to 60 prongs. In particular, it has been shown that the energy spectrum of the α-particles forming the hammer tracks is in good agreement with that observed by other workers, and also with experiments made, using the cloud chamber technique, indicating that the [Formula: see text] in this disintegration is formed in the excited state. When an electron sensitive emulsion is used it is shown that the hammer track is accompanied by the [Formula: see text] disintegration electron. The energy spectrum of the [Formula: see text] nuclei is plotted, and the mechanism of the formation is discussed for both large and small stars.
Nuclear Disintegrations caused by Fast Cosmic-Ray Neutrons in Photographic Emulsions
