Searches for magnetic monopoles with the MACRO detector at Gran Sasso

MACRO is a large area multiple component detector located deep underground in Hall B of the Laboratori Nazionali del Gran Sasso in Italy. Its active components consist of tanks of liquid scintillator and planes of limited streamer tubes. In addition, there are two planar areas covered with passive track-etch plastics. The full detector measures 72 m x 12 m x 9.6 m providing a large sensitive area for the detection of penetrating particles. Multiple electronics systems provide triggering on particles over a wide range of velocities, in particular, for slowly moving massive particles such as grand unified magnetic monopoles. MACRO is sensitive to relativistic particles as well as ones whose velocities are as low as 10(-4) c. Various portions of the MACRO detector have been operational since 1989. Various data sets have been analyzed and although no monopoles have been found, stringent flux limits have been set using a variety of techniques. This paper summarizes the capabilities of MACRO for monopole detection and presents some experimental results which have been obtained to date.