Search for Heavy Triplets in Cosmic Rays

Abstract

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 ${10}^{\ensuremath{-}2}$ ${\mathrm{m}}^{2}$ 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\ifmmode^\circ\else\textdegree\fi{} 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\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}8}$ ${({\mathrm{cm}}^{2}\phantom{\rule{0ex}{0ex}}\mathrm{s}\mathrm{r}\phantom{\rule{0ex}{0ex}}\mathrm{s}\mathrm{e}\mathrm{c})}^{\ensuremath{-}1}$ 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 \ensuremath{\mu}b for the production cross section of triplets of mass less than 15 $\frac{\mathrm{GeV}}{{c}^{2}}$.