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.
ESR Study on the Excited State Energy Spectrum of SrCu2(BO3)2–A Central Role of Multiple-Triplet Bound States–