Search for the Production ofμ-Meson Pairs by a 345-Mev Synchrotron Beam

Observations made at 45° and 90° to a 345-Mev bremsstrahlung beam failed to indicate the production of pairs of ${\mu }^{+}-{\mu }^{-}$ mesons from targets of Be and Al. From the run on Be at 45°, $\sigma \left(\mu \mathrm{pair}\right)<\left(\frac{4\times {10}^{-32\mathrm{}}}{16{\pi }^2}\right)$ ${\mathrm{cm}}^2$ ${\mathrm{}\left(\mathrm{steradian}\right)\mathrm{}}^{-2\mathrm{}}$ ${\mathrm{proton}}^{-1\mathrm{}}$. This upper limit is twenty times the value predicted by the Bethe-Heitler theory for a purely electromagnetic interaction. The result would seem to preclude any interaction between pairs of $\mu$ mesons and nucleons which is as large as ${10}^{-3\mathrm{}}$ of the strength of the interactions of $\pi$ mesons and nucleons.