LIVERMORE, Calif. — Given the threat by rogue dictators and terrorist organizations who wish to acquire their own nuclear weapons, there is a critical need for sensors that can detect the storage, transport or trade of weapons grade nuclear materials from greater distances than currently possible. To address this threat, Sandia National Laboratories has joined forces with industry, academia and other national laboratories to produce new radiation sensors that combine the advantages of high efficiency with high selectivity. These smart detectors are designed to distinguish gamma rays emitted from the radioactive materials contained in weapon systems from those emitted by other common materials, such as concrete and granite.
Given the interests sparked by recent advances in room-temperature semiconductor sensors, a group of 75 or so researchers representing most of the U.S. organizations currently working on the technology assemble Tuesday in Livermore to begin a two-day workshop on the subject. The first day of the gathering is being held at Wente Conference Center and the second day at Sandia’s Livermore site. Invited speakers agree that a wide variety of new radiation-sensing instruments based on wide-bandgap compound semiconductors are forthcoming, but significant challenges to further improve the quality of the detectors remain.
Ralph James, a Sandia researcher and chairman of the scientific workshop, is urging the group to act quickly to solve the material problems limiting the performance of radiation sensors fabricated from compound semiconductors. “Sandia has chosen to host this workshop to act as a catalyst for information exchange between organizations and to play a leading role in developing the technology for national security missions,” he said.
In addition to their usefulness in detecting production or smuggling of nuclear materials, these compact sensors are expected to provide an improved tool for obtaining detailed images of cancerous tumors. Driven by the widespread need for improved imaging systems for medical applications, industry has focused considerable resources on instrument development, product improvement and marketing, while working with the labs to better understand the fundamental properties of the crystals and their relationship to detector performance. Patrick Doty, a medical imaging researcher from DIGIRAD, said, “Gamma-ray cameras based on wide bandgap semiconductors, such as cadmium zinc telluride, will allow a quantum jump forward in our ability to spatially resolve tumors.”
These radiation sensors and imaging arrays can also be used to monitor and clean up toxics distributed in the environment. Many of the visitors at the workshop are interested in using X-ray and gamma sensors to enhance the United State’s capability to characterize and remediate waste sites, some of which are a legacy of 50 years of weapons production.
Tom Hunter, Sandia vice president, said, “The partnering of Sandia National Laboratories with universities and the industrial sector has and will continue to play a key role in advancing this technology. This partnering will result in compact, low power radiation sensors that will benefit our laboratories in national security and environmental quality and will support many U.S. industries as well. For example, this technology will help the U.S. to establish leadership in the increasingly competitive global marketplace for medical imaging.”
Sandia intends to host semi-annual workshops on room-temperature radiation sensors to nurture closer working relationships with industry and academia, report on collaborative work, and publicize sensor development successes. These strategic alliances between government labs, industry and academia will ensure the availability of these radiation sensors and imaging systems for nuclear nonproliferation, environmental cleanup, and medical applications during the coming millennium.