Date: Apr 17, 2014 Author: Sarah Schmid Source: xConomy (
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Detecting nuclear radiation is easy. All you need is a simple, inexpensive Geiger counter. But to be able to precisely identify both the type of radiation and where it is coming from is much more challenging. That’s crucial for everything from searching for possible nuclear weapons in shipping containers to performing routine maintenance or emergency response in nuclear power plants.
The problem is that devices capable of precisely imaging nuclear radiation in this way cost hundreds of thousands of dollars and are bulky and cumbersome. They typically rely on a semiconducting material called germanium, which must be cooled with liquid nitrogen to work. The radiation imagers made by Ortec used to search for smuggled nuclear materials in some of the world’s ports, for instance, are huge and weigh thousands of pounds.
But now H3D, an Ann Arbor, MI-based startup, has developed what some are calling a game-changing radiation imaging technology—a small, room-temperature, handheld device called the Polaris-H that could be sold starting at less than $100,000. “It’s changing the paradigm of radiation detection,” says Bill Hagen, the former head of the Department of Homeland Security’s Domestic Nuclear Detection Office. “What’s exciting about it is that [the Polaris-H] can tell exactly where the radiation is coming from, and it’s smaller, lighter, and can be used at room temperature. It was a big success when I was in government to have a company commercialize this technology so it’s available to officers in the field.”
The imaging of nuclear radiation for detection purposes has traditionally been a burdensome task. The most widely used imaging devices have operated like old-fashioned pinhole cameras: they’re typically big and stationary, largely because of the required cooling apparatus. They require a long exposure, and often they can’t differentiate between gamma-ray energies.
That’s why Zhong He, a professor in U-M’s Department of Nuclear Engineering and Radiological Sciences, has been working on building a better radiation detector since 1998. His original aim was to improve the ability to detect nuclear terrorism. He and his team of grad students built a suitcase-sized imaging spectrometer called the Polaris. But they quickly realized that Polaris could be put to immediate use detecting radiation in nuclear energy facilities, and they set about refining its design.
In 2011, He and a team of former grad students launched H3D from He’s university research, which has won more than $20 million in government funding throughout the past decade. H3D has shrunk the Polaris to what is now a handheld imager called the Polaris-H. Last fall, H3D began selling the Polaris-H commercially, and the company sees a number of industries in addition to nuclear energy—space science, proton cancer therapy, homeland security--where it expects its devices to have a major impact.
Willy Kaye, H3D’s president, says radiation is both invisible and deadly, which is unsettling to the people who work around it. In the past, nuclear power plants have needed workers to cart around the bulky, pinhole camera-like devices to survey rooms one small portion at a time. “But if the room is full of radiation, it’s kind of like a chicken and egg problem—how long do you survey if the surveying is giving you a dose of radiation? Wouldn’t it be great if, instead, you could take an image like infrared for heat?”
It’s possible to have robots operate the large germanium imagers, but H3D points out that in many instances, the areas that need to be checked are only accessible by ladder or are in otherwise prohibitively small spaces that robots can’t access.
H3D’s technology allows people to “see” the type and source of radiation. It can be used in the early detection of leaks, and it can also be used as a tool for cleaning up nuclear accidents and fallout, such as what happened in 2011 in Fukushima, Japan. Its introductory price for universities, national labs, and early adopters is less than $100,000 per device—and it’s small. It weighs just under 9 pounds and is roughly 8 inches long and 5 inches deep.
It also doesn’t require cryogenic cooling the way the germanium-powered devices do (more on that in a minute). It’s air- and water-tight, and Kaye says even if it becomes contaminated, it can be wiped off and decontaminated. H3D prototype devices already have been used to identify failures, verify clean-ups, and locate the primary sources of radiation before routine maintenance will be performed at the Cook Nuclear Power Plant in Bridgman, MI, and at South Korea’s Institute for Basic Science in Daejeon. Recently, several commercial units were sold to nuclear power plants around the U.S., and a few more units are on loan to other nuclear power plants on the condition that H3D receives detailed feedback.
So if the Polaris-H works so well, why doesn’t every nuclear facility in America have one? That turns out to be a complicated story.
Kaye says many have tried to make practical radiation imagers in the past, but they’ve had issues with portability and accuracy. From U-M’s office of technology transfer, where Xconomy interviewed him, Kaye took a dry-erase marker to a whiteboard to illustrate how H3D’s technology works. It hinges on a ¾-inch square block of material called CZT, which stands for cadmium zinc telluride.
CZT is a semiconductor, and Kaye says it has a bad rap in the nuclear industry because its promise has been known but unrealized for almost 40 years. What CZT offers is a compact, room-temperature replacement for germanium, which for decades has been the go-to detector material when users want to precisely record the energy distribution of gamma rays in the environment—information which is then sed to identify the radioactive isotopes producing those gamma rays.
The catch is that due to the semiconductor physics of germanium, the material can only be used when cryogenically cooled, either with liquid nitrogen or a large mechanical refrigeration unit. This means workers must begin the cool-down process many hours before any measurement can be taken. (It’s possible to have a large, cooled spectrometer on hand with perpetually refreshed liquid nitrogen, and that method is used, but H3D says it’s impractical, especially during emergencies.) Researchers knew that CZT could theoretically substitute for germanium, while operating at room temperature. But for decades, no one could make CZT detectors work—and some scientists thought it might actually be impossible to build a practical device using the material.
H3D, apparently, has done something unprecedented: It has come up with a way to make CZT competitive with germanium for almost all applications where high energy precision is needed. How? The trick was figuring out how to sense the 3D position of radiation using a single crystal of CZT. Zhong He did that by charting exactly where every gamma ray interacts in the crystal and how much energy the ray deposits with each interaction. He also developed a way to get 3D information on the locations of multiple sources of radiation using the timing of signals from the crystal. Still, it took He more than a decade to understand and make sense of the details of the readout from the CZT crystal, and to improve the electronics and calibration process enough to provide the precision needed.
“The Polaris-H can tell not only the presence of radiation, but also what kind of radiation,” Kaye says, adding that the ability to differentiate the type is key in homeland security applications. “Plus, it allows us to have [the detector] all in one battery-operated package that weighs less than 10 pounds.”
Kaye calls the core team behind H3D—himself, He, chief technical officer Feng Zhang, and sales director Weiyi Wang—remarkable. “Dr. He tries to pull top nuclear physicists,” he says. “The talent has grown in over time, so it can’t be replicated. It takes a very long, dedicated effort.”
Kaye says H3D wouldn’t exist without Zhang’s contributions in particular to developing the technology, and Zhang says his work with H3D suits him very well, as it also requires strong skills in computer programming.
In 1998, Zhang invented the legendary Proxy Hunter software to help Chinese Internet users tunnel through China’s Great Firewall without detection. Kaye says Zhang is so humble, it took his colleagues a long time to figure out his contribution to Chinese Internet freedom. (Someone in the lab finally noticed Zhang used a @proxyhunter e-mail address and asked him about it.)
“I haven’t followed Proxy Hunter for 10 years, but I imagine it’s still useful,” Zhang says. “I love this job [at H3D] because it’s the same as Proxy Hunter—we’re addressing a need that can improve lives and security. This is very new technology, not available before, with many different capabilities. Like Proxy Hunter, once it gets in people’s hands, it might do something very different.”
Zhang agrees with claims that H3D’s technology has the potential to revolutionize nuclear detection. “I’ve been working on this technology for 14 years,” he says. “I believe in it very much.”
Kaye is also a true believer. He grew up in Oregon and was working at the Pacific Northwest National Laboratory as an undergraduate when his boss introduced him to He. Kaye was already familiar with U-M thanks to its reputation as a top university for nuclear engineering, so working with He wasn’t a tough sell.
Though the research behind H3D’s devices was supported by nearly $20 million in grants to U-M from the Department of Energy, the Department of Homeland Security, and the Department of Defense, Kaye says H3D has been bootstrapped from its inception. (H3D has, however, won cash awards from the Accelerate Michigan business competition and the iCorps program.)
The H3D team is comprised of seven people, and it has begun to market its devices more aggressively now that its prototypes have been sold and are drawing praise from industry leaders like Bill Hagen. In addition to the Polaris-H, H3D has sold prototypes to NASA for use in studying radiation coming from space, and to researchers at the University of Maryland who are working on proton therapy, a highly accurate form of radiation treatment, for cancer patients.
And because H3D’s technology is able to detect what kind of isotopes are present in a truckload of radioactive material—and whether those isotopes are coming from, say, clay or kitty litter or a dirty bomb—Hagen expects that the company will have an enormous impact on homeland security, particularly at border crossings and international weapons inspections.
“The application H3D is going after first is nuclear power, but in the long run, I’m looking forward to it becoming viable and incredible for security applications,” Hagen says. (I called Ortec, a leading Tennessee-based nuclear detection company and maker of germanium-based devices, to hear their opinion on the promise of CZT, but Ortec did not respond.)
In addition to the markets that company officials have laid out in H3D’s carefully constructed business plan, the company is also excited about the potential of the technology in defense applications. “This is not a speed play,” Kaye says, in reference to H3D’s methodical approach to market capture. “We want to make sure our technology works.”