Search for Anomalous Lifetime Values in Sea-Level Cosmic Radiation

By use of a scintillation counter telescope, sea-level cosmic radiation was investigated for the existence of particles of mass greater than $60m_e$, decaying with lifetimes in the millisecond region. If such particles exist, their intensity, relative to $\mu$ mesons, for various lifetime ranges, must be as follows: for ${10}^{-4\mathrm{}}$ to ${10}^{-2\mathrm{}}$ sec, ⩽ 0.03%; for ${10}^{-4\mathrm{}}$ to 5×${10}^{-2\mathrm{}}$ sec, ⩽ 0.1%; for ${10}^{-4\mathrm{}}$ to ${10}^{-1\mathrm{}}$ sec, ⩽ 0.14%; for ${10}^{-4\mathrm{}}$ to ${10}^{-1\mathrm{}}$ sec (for decay into a light meson), ⩽ 0.03%; for ${10}^{-4\mathrm{}}$ to 1.0 sec, ⩽ 1.4%.