Improved Experimental Limits on the Production of Magnetic Monopoles
  We present new limits on low mass accelerator-produced point-like Dirac magnetic monopoles trapped and bound in matter surrounding the D\O collision region of the Tevatron at Fermilab (experiment E-882). In the context of a Drell-Yan mechanism, we obtain cross section limits for the production of monopoles with magnetic charge values of 1, 2, 3, and 6 times the minimum Dirac charge of the order of picobarns, some hundred times smaller than found in similar previous Fermilab searches. Mass limits inferred from these cross section limits are presented. 
G. R. Kalbfleisch, K. A. Milton, M. G. Strauss, L. Gamberg, E. H.   Smith, and W. Luo