New Limit on Axion Production in 800-GeV Hadronic Showers

A search for neutral penetrating particles has been made by use of an 800-GeV proton beam incident on the magnetized beam dump of the spectrometer of Fermilab experiment 605. Limits on the mass and couplings of such particles are presented. A 1.8-MeV axion coupled only to ${e}^{+}{e}^{\ensuremath{-}}$ is ruled out.