ABSTRACT: We have conducted a search for extended energy deposition trails left by ultrarelativistic magnetic monopoles interacting in Antarctic ice. The nonobservation of any satisfactory candidates in the 31 days of accumulated ANITA-II (Antarctic Impulsive Transient Antenna) flight data results in an upper limit on the diffuse flux of relativistic monopoles. We obtain a 90% C.L. limit of order 10-19 (cm2 s sr)-1 for values of Lorentz factor, γ, 1010≤γ at the anticipated energy Etot=1016 GeV. This bound is stronger than all previously published experimental limits for this kinematic range.
Phys. Rev. D. 01/2011; 83(2).