Production of prompt muons in the forward direction by 400-GeV proton interactions

The ratio of prompt negative muons to negative pions produced in the forward direction by the interaction of 400-GeV protons on copper has been determined to be 5.8times10$sup -5$ for 55-GeV muons, 3.05times10$sup -5$ for 102- GeV muons, and 1.93times10$sup -5$ for 230-GeV muons. The ratio of prompt positive muons to negative muons was about 1. (AIP)