Search for dark matter intensifies (Forwarded)

University of California-Santa Barbara

Media Contacts:
Gail Gallessich, 805-893-7220,
Joan Magruder, 805-893-8735,

Additional Resources:

David Caldwell, 650-926-2547,
Harry Helson, 805-893-8612,

FOR IMMEDIATE RELEASE: Wednesday, November 12, 2003

Search for dark matter intensifies

Today scientists announced that the search for dark matter is on -- it has been
launched from a laboratory half a mile below ground. Two professors from the
University of California, Santa Barbara -- Harry Nelson and David Caldwell --
are playing a major role in the multi-institution experiment.

"This is the best, quietist environment that we have for searching for dark
matter," said Harry Nelson, professor of physics at UCSB and one of the leading
researchers in the experiment.

Astronomers have known for 70 years that the matter we see cannot constitute all
the matter in the universe. If it did, galaxies would fly apart. Recent
calculations indicate that ordinary matter containing atoms makes up only four
percent of the energy-matter content of the universe. "Dark energy" makes up 73
percent, and an unknown form of dark matter makes up the last 23 percent.

The researchers are using a mine in Soudan, Minn. and have placed sensitive
germanium crystals, chilled to nearly absolute zero, in the mine. The location
and the temperature shield the crystals from unwanted particles that fall to
Earth's surface and "noise" from moving particles that occurs in a warm environment.

"When you hold a sea shell up to your ear, what you hear is the movement of
particles," said Nelson. If the shell were frozen, the sound would be gone.

The scientists expect that WIMPS, or weakly interacting massive particles, the
leading candidates for dark matter, will reach the crystal and cause small
sounds, which will be recorded by computer. WIMPs are theorized as particles
much more massive than protons, but interacting so weakly with other particles
that billions pass through a human body each second without leaving a trace. The
experiment needs only a few interactions to make a strong claim for detection of
WIMPS.

"It is often said that this is the ultimate Copernican Revolution," said David
Caldwell, chair of the Cryogenic Dark Matter Search (CDMS II) Executive
Committee. "Not only are we not at the center of the universe, but we are not
even made of the same stuff as most of the universe. Discovery would be a great
breakthrough, one of the most important of the century."

Nelson compared dark matter to a bowling ball surrounding the Milky Way galaxy,
with the Milky Way as we see it taking up about the space of a quarter in the
center of the bowling ball.

He explained that what is needed now is time. "After 100 days online, we will
easily surpass the world's sensitivity for detection of dark matter," said
Nelson. An Italian-Chinese team has been working on the problem as well as
French and English teams. Nelson said that the CDMS II group is at the forefront.

Funding for the experiment comes from the Office of Science of the U.S.
Department of Energy (DOE) and the Astronomy and Physics Division of the
National Science Foundation (NSF).

"CDMS II is the kind of innovative and path-breaking research NSF is proud to
support," said Michael Turner, Assistant Director for Math and Physical Sciences
at the National Science Foundation. "If it detects a signal it may tell us what
the dark matter is and give us an important clue as to how gravity fits together
with the other forces. This type of experiment shows how the universe can be
used as a laboratory for getting at some of the most basic questions we can ask
as well as how DOE and NSF are working together."

Besides UCSB, CDMS II collaborators include Brown University, Case Western
Reserve University, Fermi National Accelerator Laboratory, Lawrence Berkeley
National Accelerator Laboratory, National Institute of Standards and Technology,
Princeton University, Santa Clara University, Stanford University, University of
California at Berkeley, University of Colorado at Denver, and the University of
Minnesota.

RELATED LINKS

* Photos
http://www.fnal.gov/pub/presspass/pr...tos/index.html
* Background Information
http://www.fnal.gov/pub/presspass/pr...ackground.html
* Cryogenic Dark Matter Search Home Page
http://cdms.berkeley.edu/index.html