Search for Dirac Monopoles

Abstract

Nuclear emulsions were used to establish the following upper limits for the production of Dirac monopoles by 6.3-Bev protons:If poles of protonic mass are produced by direct nucleon-nucleon collision, the production cross section is less than 2\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}35}$ ${\mathrm{cm}}^{2}$ per nucleon.If poles of protonic or lower mass are produced by direct or by secondary processes and are subsequently held in matter with a binding energy less than 3 ev, the production cross section is less than 1.5\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}37}$ ${\mathrm{cm}}^{2}$ per nucleon.If poles of protonic or lower mass are produced by direct or by secondary processes and are subsequently held in matter with a binding energy between 3 ev and 20 ev, the production cross section is less than ${10}^{\ensuremath{-}40}$ ${\mathrm{cm}}^{2}$ per nucleon.