The author is grateful to Dr. R. Sheldon and Mr. U. Lauterburg for preparing the figures for this article. The DUMAND Collaboration expresses its gratitude to the following institutions for their support of this research project: U.S. Department of Energy; Japanese Ministry of Science (Mombusho); German Federal Ministry of Science and Technology (BMFT); Land Schleswig Holstein, Kiel, Germany; Swiss National Science Foundation; Wolfermann Naegeli Foundation, Kilchberg (ZH), Switzerland.