Experiment for search of space magnetic monopoles with a magnetic excitation mechanism

We are proceeding with the search experiment for space magnetic monopoles of velocity 5 x 10-4 c - c with a magnetic excitation mechanism established theoretically. During the about 150 days of experiment so far, there were obtained no magnetic monopole candidates. The upper magnetic monopole flux limit, that ranges between 1.7 x 10-13 cm-2s-1sr-1 (1 x 10-3 <= β < 1) and 6.6 x 10-13 cm-2s-1sr-1 (β -- 5 x 10-4), was thus obtained. Theories and experiments on the magnetic monopole are first reviewed. The experimental apparatus is described with some elaboration on the helium proportional counter. With the results of simulation calculation, validity of the experimental apparatus is examined. Events are reproduced from the experimental data, leading to the criteria for magnetic monopoles. The experimental events are then interpreted, and the results so far are compared with other experiments and theories. (Mori, K.)