Clark School Press Release Story

UMD Engineers Propose High-Tech Solution to Shipping Container "Dirty Bomb" Threat

System Would Safely Detect Ionization of Air Surrounding Containers Holding Radioactive Material

FOR IMMEDIATE RELEASE  November 22, 2010

CONTACT:
Ted Knight
301-405-3596
teknight@umd.edu

COLLEGE PARK, Md.--The shipment of cargo containers is a critical component of international trade and plays a fundamental role in the global economy. According to the U.S. Bureau of Customs and Border Protection, about 90 percent of the world's trade is transported in cargo containers, with almost half of incoming U.S. trade arrives by containers aboard ships. As terrorist organizations have increasingly turned to destroying economic infrastructure to make an impact on nations, the vulnerability of international shipping has come under scrutiny.

Researchers at the University of Maryland, College Park, have proposed a technique to remotely detect if a shipping container contents includes radioactive material, which could be used to construct dirty bombs. Ionization of air surrounding crates is a sign of radioactive material. If authorities can detect this ionization outside of the crate, they can select specific containers for inspection, improve security and avoid delays in commerce.

The concept is described in a recent article in the Journal of Applied Physics co-authored by Victor Granatstein, a professor in the A. James Clark School of Engineering's Department of Electrical and Computer Engineering and the Institute for Research in Electronics and Applied Physics (IREAP), and Gregory S. Nusinovich, a research scientist in IREAP.

Gamma-ray emission from concealed radioactive material would pass through shipping container walls and increase ionization of the surrounding air. If a device pointed a high-power, short-wavelength electromagnetic wave at the container, the breakdown in the air would be detectable.

"We would create a spark in the air at the focus of an antenna driven by a high power, coherent, electromagnetic-wave generator, such as a gyrotron or laser," explained Granatstein. "The formation of the spark would be facilitated if gamma radiation from the concealed radioactive material were present."

Detection of radioactive material concealed in shipping containers is important to the early prevention of "dirty" bomb construction. There is currently a strong interest in determining whether a container ship approaching the U.S. is transporting radioactive material that might be used in the construction of a "dirty" bomb. Since there is a very large number of container ships approaching the U.S. every day, this determination needs to be made without stopping and boarding each ship (e.g., from a helicopter flying overhead). This would require a detection system with a range of tens of meters and with adequate sensitivity to detect small but troubling amounts of radioactive material.

There is at present no detection scheme that can easily satisfy these requirements. Several approaches have been suggested and are being explored, including the method proposed by Granatstein and Nusinovich.

Such an effect then could be detected and evaluated.

Granatstein and Nusinovich are currently improving analysis of air breakdown in the presence of both gamma radiation and a high power-density electromagnetic wave in the spectral range between millimeter-waves and infrared. They are also developing a 0.67 terahertz gyrotron that will be capable of producing 300 kW, 10 microsecond pulses to be used in the experimental evaluation of the range and the sensitivity of their detection scheme. The researchers expect the gyrotron to be operating by the end of 2011.

"It is not yet clear whether this approach to detection is practical," said Granatstein. "But it is worth pursuing, since it might impact an important need related to national security."

The Office of Naval Research is supporting this study under a five-year research grant that began in September 2009.

The article describing the research, titled "Detecting Excess Ionizing Radiation by Electromagnetic Breakdown of Air," by Victor L. Granatstein and Gregory S. Nusinovich, appears in the Journal of Applied Physics, and can be accessed at http://link.aip.org/link/japiau/v108/i6/p063304/s1. This research is described in more detail in a paper titled "Development of THz-range Gyrotrons for Detection of Concealed Radioactive Materials," which will soon be published in the Journal of Infrared, Millimeter and Terahertz Waves. The paper is already available on the journal’s website.

About the A. James Clark School of Engineering

The Clark School of Engineering, situated on the rolling, 1,500-acre University of Maryland campus in College Park, Md., is one of the premier engineering schools in the U.S., with graduate and undergraduate education programs ranked in or near the Top 20. In 2012, the Clark School was ranked 14th in the world by the Institute of Higher Education and Center for World-Class Universities in its Academic Ranking of World Universities. Three faculty members affiliated with the Clark School were inducted into the National Academy of Engineering in 2010.

The school, which offers 13 graduate programs and 12 undergraduate programs, including degree and certification programs tailored for working professionals, is home to one of the most vibrant research programs in the country. The Clark School garnered research awards of $171 million last year. With emphasis in key areas such as energy, nanotechnology and materials, bioengineering, robotics, communications and networking, life cycle and reliability engineering, project management, intelligent transportation systems and aerospace, the Clark School is leading the way toward the next generations of engineering advances.