Search for Dirac magnetic monopoles in e+e− collisions with the OPAL detector at LEP2

This Letter describes a direct search for pair produced magnetic monopoles in e+e− collisions. The analysis is based on 62.7 pb−1 of data collected with the OPAL detector at an average centre-of-mass energy of s=206.3GeV. The monopole signal was assumed to be characterized by two back-to-back particles with an anomalously high ionization energy loss dE/dx in the tracking chambers. No evidence for production of monopoles was observed. Upper limits were obtained on the magnetic monopole pair-production cross-section (σ) in the mass range 45GeV/c2