New tools counter biological and chemical terrorism
In the November
21, 2003, issue of Science, three Livermore researchers
discussed the recent progress in technology development to counter
biological and chemical terrorism. The scientists noted that
although important challenges remain, new detection systems show
increased sensitivity, greater automation, and fewer false alarms.
In their paper, Pat Fitch and Dennis Imbro, who work in Livermore’s
Chemical and Biological National Security Program, and Ellen Raber,
who leads the Environmental Protection Department, say that technologies
for countering bioterrorist agents are approaching the sophistication
of technologies for fighting chemical warfare agents. Nevertheless,
improvements are still needed for sensors to meet the high level
of sensitivity needed to protect civilians and to reduce the high
rates of false alarms.
The researchers also describe a decision-making framework of four
phases to guide response activities following a terrorist attack:
notification, first responder, characterization, and restoration
(or decontamination and remediation). During the initial notification
phase, an operations center identifies an event using data from
sensors and intelligence analysis as well as information on casualties.
The first-responder phase is likely to include such actions as
isolating or stabilizing hazardous materials or taking care of
casualties. The characterization phase focuses on determining key
site parameters, including time since release, extent of contamination,
and potential risks to human health and the environment. The final
restoration phase involves selecting site-specific decontaminating
reagents, if required, and sampling to verify that all long-term
environmental issues have been addressed and the solutions meet
The scientists cite several reasons for the substantial improvement
in biological detection. For example, polymerase chain reaction
can be used to amplify DNA for rapid analysis, and the development
of very specific DNA signatures for pathogens provides more accurate
identification. Another factor for success is that many tests and
controls can be conducted simultaneously. The researchers caution
that despite these advances, technical and logistical challenges
still exist to effectively prevent or combat chemical and biological
Contact: Pat Fitch (925) 422-3276 (email@example.com).
Another view of black hole phenomena
When most people think of black holes, they think of an area of
space where matter can disappear. But that view is inconsistent
with quantum mechanics.
1991, Laboratory physicist George Chapline suggested that this
inconsistency could be avoided if the vacuum state of ordinary
space–time is assumed to be a kind of superfluid. The formation
of black holes would correspond to a “squeezing” of
the vacuum—a quantum process roughly analogous to the compression
of an ordinary fluid.
More recently, Chapline and colleagues at Stanford University have
extended this idea to account for the event horizon of a black
hole. They proposed that near the event horizon surface of a black
hole, ordinary space undergoes a continuous phase transition to
a phase with a much larger vacuum energy than the cosmological
vacuum energy inferred from observations of distant supernovae.
The physicists have predicted that near the surface of a black
hole, matter behaves in a markedly different way from what is predicted
by classical general relativity.
holes are generally believed to be remnants of stars that have
collapsed into themselves. This gravity can pull in and obliterate
objects that approach the surface. Chapline’s group believes
that black holes are actually extended bodies made up of “dark
energy.” In this view, matter doesn’t disappear when
it falls inside the event horizon surface of a black hole, but
it can be transformed when it crosses the surface.
notes that the behavior of sound waves crossing a critical surface
in a vertical column of a superfluid model provides the
necessary insight into what happens to relativistic particles when
they approach an event horizon. “The energy of the relativistic
particles will become a quadratic function of momentum as they
approach the surface,” he says. “Above a certain energy,
the particles will become unstable as they cross the surface.”
a result of this instability, a star falling onto the surface of
a large black hole or a massive star undergoing gravitational
collapse will emit pulses of radiation with characteristics that
are similar to those of some cosmic gamma-ray bursts. An article
about this work appeared in the July
2003, issue of Scientific
Contact: George Chapline (925) 422-4106 (firstname.lastname@example.org).
Search for planets yields shock-wave breakthrough
inexpensive interferometer developed to help astrophysicists search
for planets is also being used to boost the time resolution
and stability of streak cameras that record high-speed phenomena,
such as those that occur in shock-wave physics experiments. The
externally dispersed interferometer (EDI) was first proposed in
1998 in a project led by Livermore physicist David Erskine. The
system combines the white-light velocity interferometry techniques
used on the Laboratory’s two-stage gas guns with an external
grating spectrograph for astronomical imaging.
can be used to precisely measure small shifts in Doppler velocity.
These shifts in the wavelength of starlight are caused
by the motion of a planet around a star. Light passing through
the periodic fringes of an interferometer and into the spectrograph
creates a moiré pattern. This moiré pattern shifts
transversely in proportion to the Doppler velocity. The EDI eliminates
atmospheric distortions, which can reduce the precision in Doppler
or spectroscopic measurements.
1999, when Erskine and his team tested the system at the University
of California’s Lick Observatory on Mount Hamilton, they
found that the EDI reduces the distortion of starlight. More recently,
using information in the moiré patterns with special software,
they demonstrated that the EDI can boost the spectrograph resolution
at Lick by two times.
realized the EDI could also be used to improve the time resolution
and stability of streak cameras, such as those used
in experiments at the National Ignition Facility. Such a boost
in time resolution is analogous to the increase in spectral resolution
for astrophysical measurements.
potential applications for the EDI include high-resolution spectroscopy
over a broad bandwidth, boosting the resolution and
stability performance of existing spectrograph facilities, and
searching for exoplanets by measuring stellar angular positions.
More information on the improved spectral resolution from the EDI
is available in the August 1, 2003, issue of Astrophysical
Contact: David Erskine (925) 422-9545 (email@example.com).