(Gengwu fifth day of the first month), January 31, 1990, in Europe to determine the neutrino only three electron-positron collider. In January 1990, the European nuclear physics research center uses 27 kilometers in circumference "Levin splashed electron-positron collider, the total width of the middle of the four experimental groups Z0 boson decay and a part of the width, to reliably determine the neutrino only three. (Lssjt.cn)