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Fall 2011 Vol. 11 Number 2

Table of Contents

©Mehau Kulyk/Science Photo Library/Corbis

Should U.S. Physics
Research Go Underground?

Experiments Deep Beneath the Earth’s Surface Could
Provide Significant Breakthroughs

Physicists have long been intrigued with the study of neutrinos — “ghost” particles that fill the universe and interact only weakly with ordinary matter. Many researchers believe that neutrinos could answer some of science’s most profound questions, such as how the universe began. Laboratories located deep underground provide the extremely quiet environment needed to study neutrinos’ faint signals, as well as rare events such as proton decay. World-class underground laboratories have been built in Canada, Japan, and Europe, but U.S. efforts in this area have been modest to date.

Recently, scientists engaged in this type of research developed an integrated suite of experiments centered around the Deep Underground Science and Engineering Laboratory (DUSEL), a major research facility proposed for location in a former mine in Lead, South Dakota. The National Science Foundation and the U.S. Department of Energy, which have overseen the effort to develop the DUSEL program, asked the National Research Council to assess the scientific value of the physics experiments proposed for the laboratory and the need to conduct the research in the U.S., given the existence of similar science programs in other countries. During the course of the study, however, NSF announced it would no longer be the principal steward for the facility. The two agencies are deciding how to proceed.

The Homestake Mine in Lead, South Dakota, photo by Reidar Hahn, courtesy Fermilab Visual Media ServicesShould the project move forward, three major experiments are planned for DUSEL. The direct detection dark matter experiment would broaden knowledge about dark matter, a substance that makes up approximately 80 percent of the material universe. The long-baseline neutrino oscillation experiment would advance the study of neutrinos and enable other important physics research, such as examining whether protons decay. And the neutrinoless double beta decay experiment would establish the only practical setting to determine whether neutrinos are their own antiparticles, information vital to understanding how particles came into existence in the early universe.

The Research Council’s report found that these experiments would present exceptional opportunities for major scientific advances and give the U.S. a leading role in underground science. Each of the principal experiments addresses scientific questions of “paramount importance” that would give physicists a foundation of study for decades to come.

Benefits to the U.S. particle and nuclear physics communities would be greatest if the three experiments are led and conducted in a U.S.-based facility, the report says. In particular, performing the long-baseline neutrino oscillation experiment in the U.S. would make the nation a world leader in this area because researchers could also draw on the capabilities of the Fermilab accelerator complex, located in Illinois. In addition, co-locating the three experiments in one facility would also allow for efficient sharing of infrastructure and personnel. However, if a domestic site is not available for the dark matter and neutrinoless double beta decay experiments, U.S.-led projects in sites abroad would still impart important benefits to the nation’s research communities, the report notes.

Although the final decision on building an underground national lab will involve many factors, including costs and the goals of funding agencies, such a laboratory could offer considerable advantages over sending U.S. scientists to conduct experiments at facilities in other countries. A U.S. facility would assure the United States a leadership role in underground science and particle physics; would provide U.S. scientists access to experiments in a laboratory on U.S. soil; and it could help meet increasing global demands for underground research facilities. What’s more, other areas of science such as geology and biology could also reap benefits from the facility, the report says.
  -- Molly Galvin

An Assessment of the Deep Underground Science and Engineering Laboratory. Ad Hoc Committee to Assess the Science Proposed for a Deep Underground Science and Engineering Laboratory (DUSEL), Board on Physics and Astronomy, Division on Engineering and Physical Sciences (2011, approx. 94 pp.; ISBN 0-309-217237; available from the National Academies Press, tel. 1-800624-6242; $21.00 plus $5.00 shipping for single copies).

The committee was chaired by Andrew Lankford, professor of physics and astronomy at the University of California, Irvine. The study was funded by the National Science Foundation and the U.S. Department of Energy.

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Copyright 2011 by the National Academy of Sciences