We describe a search method for fast moving (β>5×10−3)
magnetic monopoles using simultaneously the scintillator, streamer tube and
track-etch subdetectors of the MACRO apparatus. The first two subdetectors are
used primarily for the identification of candidates while the track-etch one is
used as the final tool for their rejection or confirmation. Using this
technique, a first sample of more than two years of data has been analyzed
without any evidence of a magnetic monopole. We set a 90% CL upper limit to the
local monopole flux of 1.5×10−15cm−2s−1sr−1 in the
velocity range 5×10−3≤β≤0.99 and for nucleon decay
catalysis cross section smaller than ∼1mb.Comment: 29 pages (12 figures). Accepted by Astroparticle Physic