An example of a ז-meson generated in a nuclear encounter at high energy

Abstract

In one of a sandwich of two Ilford G 5 plates 1200 μ thick, exposed emulsion to emulsion at an altitude of 90000 ft. for 5½ h, and at a geomagnetic latitude of 40° N in one of the Sardinian flights of 1952, a ז-meson was observed to have been emitted from a nuclear disintegration. In the adjacent plate the ז-meson was brought to rest and subsequently decayed. A photograph of the tracks is shown in figure 41, plate 13. The star is comprised of ten minimum tracks, one of which may be attributed to the primary, three black tracks, and one grey track (that due to the ז-meson). The ‘primary ’ and axis of the shower are inclined at 60° with respect to the plane of the emulsion, thus permitting no direct energy measurements; however, considering the median angle of the shower and its multiplicity, the primary energy has been estimated to be at least 30 GeV.