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NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competences and with regard for appropriate balance.

This project was supported by Grant No. PHY-0223181 between the National Academy of Sciences and the National Science Foundation. Any opinions, findings, conclusions or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the views of the organizations or agencies that provided support for the project.

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Cover: The Super-Kamiokande Detector. Courtesy of the Kamioka Observatory, Institute for Cosmic Ray Research (ICRR), University of Tokyo.

Copyright 2003 by the National Academy of Sciences. All rights reserved.

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