Search for massive magnetic monopoles using plastic track detectors characteristics of CR-39 plastic for detecting monopoles

We are setting up a large scale (1000 m²) monopole search experiment using a highly sensitive plastic track detector CR-39. By applying a heavy etching method, this detector will perform a background-free search for GUT monopoles down to a flux of 10^-16 cm^-2 sec^-1 sr^-1 in the velocity range 10^-3 < β < 1. To realize such an experiment, we have made some effort for improving the sensitivity of CR-39 plastic and the uniformity of thickness, and for reducing the number of background holes. These results will be reported as well as our experimental plan.