Search for Massive Particles in the Cosmic Radiation at Sea Level

We have found no evidence for the existence of long-lived, massive particles in the cosmic radiation at sea leavel. The experimental limit for masses above 2 BeV/${\mathit{c}}^2$ is 2.2 × ${10}^{-8\mathrm{}}$ particles ${\left({\mathrm{cm}}^2\mathrm{s}\mathrm{r}\mathrm{s}\mathrm{e}\mathrm{c}\right)}^{-1\mathrm{}}$.