Search for Heavy Triplets in Cosmic Rays

A search for heavy stable particles in cosmic rays has been concluded. While the experiment was particularly designed to detect heavy triplets which might form the bases of the ${\mathrm{SU}}_3$ symmetries observed in elementary particles, the results also concern particles of other possible origins. Particle detection was accomplished by means of a mass spectrograph which incorporated fast time-of-flight techniques and momentum analysis for the measurement of particle mass. The spectrograph had an aperture of ${10}^{-2\mathrm{}}$ ${\mathrm{m}}^2$ sr, a time-of-flight resolution of 2.5 nsec, and a maximum detectable momentum greater than 300 $\frac{\mathrm{GeV}}{c}$. Measurements were made at an angle of 75° with respect to the zenith. Four possible heavy particles were found in 700 h of running, where estimates indicate that five background events were to be expected for the run. The results set an upper limit of 2.4×${10}^{-8\mathrm{}}$ ${\left({\mathrm{cm}}^2\mathrm{s}\mathrm{r}\mathrm{s}\mathrm{e}\mathrm{c}\right)}^{-1\mathrm{}}$ to the flux of particles with a velocity between $0.5c$ and $0.75c$. Calculations based on plausible assumptions for triplet production in nucleon-nucleon interactions and based on the results of this experiment give an upper limit of about 2 μb for the production cross section of triplets of mass less than 15 $\frac{\mathrm{GeV}}{c^2}$.