One of the big fears of the national security establishment in the U.S. is the threat of the detonation of a nuclear device in a U.S. city by a terrorist group. Radioactive materials are tightly controlled in the U.S. by the Nuclear Regulatory Commission. If terrorists are unable to obtain nuclear materials within the U.S., then they might attempt to smuggle them into the U.S. in a cargo container.
Port security in the U.S. has struggled for years to increase the inspection of cargo containers entering the U.S. at points of entry. Currently, the U.S. authorities use computers to review the manifests of cargo containers bound for the U.S. Any cargo containers that arouse suspicion are x-rayed and tested for neutron emissions before being allowed to enter the U.S.
A team of chemists and physicists from Washington University in St. Louis is working on a better computer chip that will help improve radiation detection in cargo shipments entering the U.S. They are working with Texas A&M University as part of a five year ten million dollar grant for research in low-energy nuclear science. The money is being provided by the Department of Energy/National Nuclear Security Administration’s (DOE/NNSA) Center for Excellence in Nuclear Training and University-based Research.
Robert J. Charity and Lee G. Sobotka at Washington University are working on a new approach for neutron detection that includes the design and construction of a new type of computer chip. George Engel, a professor at Southern Illinois University in Edwardsville, is helping with the design of the chip.
Sobotka said, “The problem with existing neutron detectors is that they are too big to get fine position information. They needed to be big to get the required detection efficiency. The solution is to have many — tens of thousands — of small detectors. This had not been contemplated before as it requires a signal processing stream for each of the small detectors.”
Application-Specific Integrated Circuits (ASICs) are the basis of data processing in computers, cell phones and other electronic devices. These sophisticated chips are designed and fabricated for the very specific efficient processing needed by a particular device for a particular application. The design and fabrication are complex and scientists don’t usually use ASICs for prototypes of devices.
Two ASIC chips designed by the researchers will be used in combination with a particular organic crystal in their neutron detector. They will then carry out high-resolution experiments with neutron sources that cannot be accomplished with current technology.
In addition to improving the detection of neutrons during the inspection of cargo, the new device containing the new chips and organic crystal will also advance our understanding of atomic nuclei. The new device will allow the researchers to improve the current model of the distribution of neutrons in the nuclei of heavy metals such as uranium and plutonium.
Any improvement in neutron detection that can be successfully scaled to industrial production and economic price points will be a boon to insuring national security and prevent the smuggling of radioactive materials.