When Michigan Nuclear Engineering and Radiological Sciences professor Zhong He and his company, H3D, started selling the Polaris-H radiation detector in 2013, many hailed it as a game-changer for nuclear safety.
Game-changing, maybe. But He is quick to point out this didn’t happen overnight. The technology is actually older than some undergraduates.
He and generations of graduate students in his Orion Radiation Measurement Group – some of whom now work for H3D – have spent 18 years developing the world’s first portable, practical gamma ray camera. The toaster-size handheld device not only detects radiation but shows exactly where it’s located and identifies the radioactive material that’s spewing it.
Originally developed for the U.S Department of Defense in order to detect nuclear weapons, He’s technology now helps doctors track the precise path of radiation therapy and is being built into NASA rovers. In nuclear power plants around the world, it detects radiation and fuel leaks, which can be both dangerous and costly.
Gamma ray detectors typically fall into two groups: scintillation detectors, which are portable but can’t show where radiation is coming from, and germanium detectors, which provide much more information but are big and heavy, with components that must first be cooled to minus-200 degrees Celsius. He’s gamma camera provides as much information as the germanium detectors and works at room temperature.
“What people really love is the imaging capability,” He said. “You can see where the source is.”
Without the ability to pinpoint the radiation source, he said, nuclear power plants have sometimes put protective shielding around a suspected radiation source, only to find later that the radiation was coming from somewhere else.
“Hopefully, we can provide a tool so people can generate nuclear power more safely, and hopefully, we can see someday that we’ve prevented some accidents from happening,” He said.
He studied nuclear physics as an undergraduate in China – a natural path for a young man who’d always been curious about the universe and the way things work. That led to graduate work with gamma ray telescopes as part of China’s High Energy Physics Institute. Unlike optical telescopes which can only reveal the surface physics of a star, gamma ray scopes reveal how the stars were formed and, by extension, answer questions about the evolution of the universe.
Gamma rays fascinated He. Unlike the photons that make up visible light, gamma rays can’t be contained. They behave more like bullets than waves, passing through anything in their path. They’re challenging to work with, but the information they reveal about a material’s nuclear workings make it worth the trouble.
Michigan’s reputation in radiation detection research – along with its proximity to Ontario, Canada, where He’s wife was working on her PhD – would eventually draw him to Ann Arbor, where his fascination with gamma rays has continued to shape his career.
He began working on the Polaris technology in 1997, gaining momentum as advances in materials and electronics gradually brought performance up and production prices down. He launched H3D in 2011 and started selling detectors commercially in 2013.
The company is now working to evolve the original system into a modular one called Orion – the constellation to Polaris’s lone star – that would detect and identify radiation over large areas. Orion’s electronics are more sophisticated and compact than Polaris’s, with components that can be configured to changes in scale.
“With Orion you can build bigger and bigger systems, and also you can make arrays of systems,” He said. “If, say, the military was using it, everybody can have a small sensor, and then they form a human network.”