Physics
Ultracold
Plasmas Are a Chilling Puzzle
Plasmas,
which include the bright glowy stuff in a fluorescent lamp, are
clouds in which ions and free electrons move around independently
as charged particles. Plasma is thought to be the most common
form of matter in the universe, but it’s usually pretty hot.
The plasma in a solar corona can have a temperature in the millions
of degrees. Researchers at the National Institute of Standards
and Technology’s Physics
Laboratory, however, have created “ultracold” plasmas—with
the electrons about a degree above absolute zero—by cooling
neutral atoms to within a hundred-thousandth of a degree of absolute
zero and then zapping them with just enough laser energy to separate
the electrons and ions to achieve the plasma state.
One
of the key measures of any plasma is the recombination rate—how
fast the ions and electrons recombine to form neutral atoms. Theory
says there are three main recombination processes, and their efficiency
varies in a known way with temperature and density. However, NIST
physicist Steven Rolston says that in practice, an expanding ultracold
plasma recombines much faster than expected at very low densities—so
much faster that no existing theory describes it.
Rolston
and his group are continuing to refine their experiments to explain
the behavior of ultracold plasmas, which, although they only exist
in earthly labs, are thought to model the interior of white dwarf
stars or gas giant planets like Jupiter. The research also may
uncover a path to synthesizing “anti-hydrogen” atoms,
the antimatter equivalent of hydrogen. Precise comparisons of
the properties of such antimatter twins may probe the fundamental
nature of the forces that bind matter and the universe together.
Media
Contact:
Michael
Baum, (301) 975-2763
Law
Enforcement
A Trip
to the ‘Library’ May Help Catch Computer Villains
Criminals
who use computers in their work frequently manipulate files
in an attempt to hide or obscure their activity. For example,
someone involved in the sale of child pornography might try
to hide a photographic image file in a computer—such as
a “jpeg” or “bitmap” file—by renaming
it to make it look like another type of file.
While
computer forensics experts know these tricks, they frequently
face the daunting task of searching up to 100,000 files on a
single desktop computer for evidence. Now, computer scientists
at the National Institute of Standards and Technology are providing
a means of speeding up these previously time-consuming evidence
searches.
Working
with software manufacturers and others who provided copies of
their programs, NIST has developed the National
Software Reference Library. The NSRL allows law enforcement
agencies to eliminate between 25 percent to 95 percent of the
total files in a computer, concentrating only on those that
really might contain evidence. It works by providing a verified
reference data set of file “fingerprints” based on
file contents rather than other identifiers such as file name
or header information.
Several
federal agencies support the effort, including the National
Institute of Justice, the Federal Bureau of Investigation, the
U.S. Customs Service, the Technical Support Working Group and
the Defense Computer Forensics Laboratory.
Media
Contact:
Philip
Bulman, (301) 975-5661
Chemistry
New
NIST Test Says ‘Y’ Be Uncertain about DNA Identification
When
researchers sought to learn whether President Thomas Jefferson
had a child with a slave, they used a “Y chromosome test”
that showed the boy was fathered by someone from the President’s
family. Such tests indicate both the presence of male DNA in a
blood or tissue sample—only males have Y chromosomes—and
the family it came from, because the markers (particular chemical
sequences) identified in the test are inherited.
Such
tests were not used widely in the past because of a number of
uncertainties. But usage is expected to increase now that the
National Institute of Standards and Technology’s Chemical
Science and Technology Laboratory has developed a more detailed
and reliable method and, in turn, is creating a Standard Reference
Material that labs will use to calibrate their instruments and
validate test performance. The new test identifies 20 markers
on the Y chromosome instead of the six used in older tests; the
standard is expected to be ready for sale next year.
The
new NIST methodology and SRM are expected to help simplify paternity
testing as well as eliminate current problems distinguishing between
male and female DNA in forensic and human ID tests.
The
markers used in the test are short, brief chemical sequences repeated
in pairs—often many times—in a DNA molecule. They vary
enough in a population to distinguish individuals and produce
good analytical results. None of the markers are believed to occur
on X chromosomes, carried by both males and females.
Media
Contact:
Michael
E. Newman, (301) 975-3025
Materials
New Imaging
Tool Has X-Ray Eyes
Researchers
at the National Institute of Standards and Technology have developed
a new way of seeing—with X-ray “eyes” no less.
Using its novel instrument, the NIST team can clearly glimpse
minute voids, tiny cracks and other sometimes indiscernible microstructural
details over a three-dimensional expanse in a wide range of materials,
including metals, ceramics and biological specimens.
In
its current form, the technology—called ultra-small-angle
X-ray scattering or USAXS imaging—functions much like a film
camera, albeit a highly specialized one. And where a camera needs
a flash to create images, USAXS has the ultimate flash—the
Advanced Photon Source at the Argonne National Laboratory. Measuring
1,104 meters (nearly 0.7 mile) around, the APS is a new-generation
synchrotron. It produces an abundance of extremely uniform high-energy
X-rays that make the new imaging technique work.
USAXS
itself is an already established research technique, yielding
plots of data points that correspond to angles and intensities
of X-rays scattered by a specimen. With the new system, graphed
curves become high-resolution pictures. And when taken from different
perspectives, pictures can be assembled into three-dimensional
images.
Images
are actually maps of the small fraction of X-rays that—instead
of being absorbed or transmitted through the sample—are scattered
by electrons in the material.
Media
Contact:
Mark
Bello, (301) 975-3776
NIST
Named National Historic Chemical Landmark
The
American Chemical Society, the world’s largest scientific
society, has declared nearly 40 places, discoveries and achievements
as national historic chemical landmarks. Among the facilities
honored over the years are the Chandler Chemistry Laboratory at
Lehigh University in Bethlehem, Pa. (the first in the United States
built specifically to train industrial chemists); the University
of California, Berkeley’s Gilman Hall (site of the identification
of plutonium); and New York’s Rockefeller University (home
to five Nobel laureates in chemistry for breakthrough work on
proteins and nucleic acids).
Now,
you can add the National Institute of Standards and Technology
to the illustrious ACS list.
The
landmark designation awarded NIST by the ACS is an outstanding
tribute that caps off an exciting centennial year for the agency.
NIST was cited as having “made broad-based and comprehensive
contributions to chemical science and technology and to the economic
strength and competitiveness of the United States.” ACS added
that NIST “continues to demonstrate that the intelligent
application of research in physical sciences to a wide range of
societal changes contributes to a higher quality of life for everyone.”
For
more information about the National Historic Chemical Landmarks
program, including the NIST declaration, go to http://center.acs.org/landmarks.
Media
Contact:
Michael
Newman, (301) 975-3025
Fellowships
Video
Says ‘SURF’s Up’ Again for NIST Summer Student
Program
Since
1993, the National Institute of Standards and Technology—with
support from the National Science Foundation—has opened up
its laboratories to undergraduate students each summer, giving
these young scientists and engineers a golden opportunity to work
alongside some of the world’s leading experts in science
and technology. Known as the Summer Undergraduate Research Fellowship—or
SURF—the program offers students majoring in science, mathematics
and engineering 12 weeks of unique hands-on learning and direct
participation in research efforts within the physics, materials
science, chemistry, applied mathematics, computer science or engineering
environments at NIST’s Gaithersburg, Md., headquarters.
The
2002 SURF program is expected to run between May 28 and August
16 of next year. Applications—which are submitted by colleges
and universities, not individual students—must be in by Feb.
15, 2002.
Persons
and organizations wanting to know more about the SURF program
should get a VHS video or compact disc copy of a new video available
from NIST titled “Wave of the Future: In Their Own Words.”
In the 8-1/2 minute show, former SURF students reflect on their
experiences in the laboratory, within the NIST campus, and around
the Greater Washington, D.C., area.
For
a copy of the SURF video or to get more information on the fellowships,
contact the SURF Program, NIST, 100 Bureau Dr., Stop 8400, Gaithersburg,
Md. 20899-8400; nist_surf_program@nist.gov.
The video and program details also are available online at www.surf.nist.gov/surf2.htm.
