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Scientists at Brookhaven National Laboratory and five other U.S.
Department of Energy (DOE) laboratories are building the largest
accelerator-based source of neutrons to probe the atomic structure
of matter, which, when completed in 2006, will be located at Oak
Ridge National Laboratory (ORNL) in Tennessee.
 The facility, called the Spallation Neutron Source (SNS), will
provide the most intense pulsed neutron beams in the world for use
in scientific research and industrial development. When completed,
the SNS will provide the information that scientists need to improve
materials used in high-temperature superconductors, and devise
powerful lightweight magnets, better lubricants, and stronger,
lighter plastic products, among other uses.
The
SNS will consist of an accelerator system producing short and
powerful pulses of protons, which will strike a mercury target and
knock out, or “spall,” neutrons. Brookhaven is responsible for designing and
constructing the part of the accelerator system called the
accumulator ring, which bunches and intensifies the proton beam
before it is delivered to a mercury target. See more on
how it works.
 Using
neutrons to look inside materials dates back to the 1940s,
when physicists Ernie Wollan and Clifford Shull conducted the
world’s first neutron-scattering experiments at a nuclear reactor at
ORNL. At BNL, the High Flux Beam Reactor was one of the world's
premier reactor neutron research sources for 30 years.
Starting in the 1960s, scientists started developing
accelerator-based pulsed neutron sources, also called spallation
neutron sources. While the continuous neutron beam from a reactor is
ideal for mapping particle specific energy changes, a pulsed neutron
beam from an accelerator-based source allows scientists to probe
various energy changes in matter simultaneously.
The need for a spallation neutron source in the United States was
first expressed in a 1993 report by the Basic Energy Sciences
Advisory Committee (BESAC) to DOE. In 1996, DOE concurred with
BESAC’s follow-up recommendation that an accelerator-based
spallation neutron source be designed. In the FY 1996 budget,
Congress appropriated $8 million to begin work on this new source.
DOE directed the SNS funds to ORNL, to initiate research and
development, and the conceptual design. The current total budget for
the SNS is about $1.4 billion, with an expected completion date in
2006.
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