Sensor detects hidden nukes

Argonne, Ill.—A small, portable sensor for finding concealed nuclear weapons and materials is in development by the U.S. Department of Energy's Argonne National Laboratory.

When fully developed, the device could assist international inspectors charged with preventing smuggling and unauthorized use of nuclear weapons and materials.

The heart of the Argonne device is a small wafer of gallium arsenide (GaAs), a semiconducting material similar to silicon. When coated with boron or lithium, GaAs detects neutrons, such as those emitted by the fissile materials that fuel nuclear weapons. Patents are pending on several detectors and their components.

The wafers are small, require less than 50 volts of power, and operate at room temperature. They also withstand relatively high radiation fields and do not degrade over time.

"The working portion of the wafer is about the diameter of a collar button but thinner," said Raymond Klann, who leads the group from Argonne's Technology Development division, which developed the wafer and detector. "It is fairly straightforward to make full-sized detector systems the size of a deck of cards or even smaller. Something that small can be used covertly, if necessary, by weapons inspectors to monitor nuclear facilities."

The key to detection, he said, is to coat the GaAs with something such as boron or lithium. When neutrons strike the coating, they produce a cascade of charged particles that is easy to detect.

The wafers consist of inexpensive, conventional microchip processing techniques, Klann said. They can be tailor-made for specific applications by varying the type and thickness of the coating.

Compared with other neutron detectors, Klann's have a number of advantages.

A tube of gas is the basis of one common type of neutron detector. The tube ionizes when neutrons pass through the tube. These detectors are larger and require more power than the GaAs detector.

Another common neutron detector uses silicon semiconductors. Compared with the GaAs wafer, silicon-based detectors use more power, require cooling, and degrade faster when they are exposed to radiation.

Klann's team also found that detection improves by etching the wafer with cylindrical holes, like the dimples on a golf ball.

Biosensor gives food a glow

Clemson, S.C.—A new biosensor may soon make contaminated food glow in the dark.

E. coli, listeria, Campylobacter, salmonella are weapons terrorists could use to strike at our food or water supply. That is where researchers at Clemson University come in: They are working on an early warning detection system.

A team of Clemson chemists, microbiologists, and food scientists devised a way to tether luminescent molecules to food pathogens, such as E. coli and salmonella. Using nanotechnology, the researchers are building a new screening method to protect our food supply.

"What's needed is a simple, low-cost way to rapidly detect pathogens at the site of contamination, not having to wait for lab results," said food science professor and team leader Paul Dawson. "What we have worked on are particles that are luminescent, providing a way to flash an alarm to hold the food for closer examination."

Chemists used a similar technique to identify worms in pecans. The worms would absorb a chemical that would glow under ultraviolet or "black" light. Dawson and his team miniaturized the process by applying nanotechnology, the science of building structures at molecular and atomic levels.

Nature does a great job of putting together molecules and other nanoscale components in complex patterns, Dawson said. His team is working on a single molecule process, creating a "protein key" that would "key and lock" with another molecule and

creating a bioalarm. Most pathogens and toxins have a unique "lock," and by attaching the matching "key" on the surface of a luminescing nanoparticle, the researchers can create a nanosensor. The sensor signal can rapidly detect and be a first line of defense in identifying contaminated food or water.

"The nanoparticle can move into crevices in the food source, where a pathogen could be hidden from microscopic view," Dawson said. "The particle's extremely small size increases the odds that the antibody and antigen will link, enabling the sensor to give off a glow. The more connections, the greater the glow.

Chemical industry moves to secure networks

Midland, Mich.—The thought of the wrong person tapping into a chemical plant's network brought together a cross section of chemical trade associations and individual companies to endorse an industry cybersecurity strategy.

The group, called the Chemicals Sector Cyber-Security Information Sharing Forum, developed a strategy focusing on cybersecurity risk management and reduction. The goal is to provide secure information and process control systems that will enable businesses to collaborate.

The forum consists of senior-level company officials and representatives of trade associations. David Kepler, Dow Chemical Co. corporate vice president and chief information officer, heads the forum.

Cybersecurity is an integral part of overall security and a natural extension of the industry's practices for securing information and other systems, as well as environmental health and safety, according to a forum statement. The forum aims to define an action plan to develop the cybersecurity standards, products, and practices necessary to shield proprietary information and facilitate safe operations.