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Downsizing for Neutron Detection

Nicole McFarlane, assistant professor of electrical engineering and computer scienceThe earliest known camera captured image dates back to 1826 from the Burgundy region of France. The photo itself is dark and grainy, barely hinting at the shape of several buildings visible from the photographer’s upstairs window. In the nearly 200 years since then camera technology has advanced into a device that fits in a pocket and takes crystal clear images of its subjects. Specialized imaging devices have been developed for studying a variety of subjects, ranging from distant galaxies to subatomic particles such as neutrons.

Graduate students working in Nicole McFarlane's labIt is the latter subject that has drawn the attention of Nicole McFarlane, assistant professor of electrical engineering and computer science, and is the focus of her Joint Directed Research and Development (JDRD) project, now in its second year of funding. McFarlane’s JDRD team seeks to improve the imaging technology used for neutron detection through the creation of a complementary metal-oxide semiconductor (CMOS) chip.

“We’re working on an optical detector, but it’s really for neutron detection. Then our plan is to take it to Oak Ridge and actually test it with the neutron source,” said McFarlane.

Neutron detection is a popular imaging method used at Oak Ridge National Laboratory (ORNL) for a variety of materials, from strands of DNA to chunks of rock. This imaging is currently performed with cameras that use Photomultiplier tubes, which are large and expensive.

Equipment in Nicole McFarlane's labMcFarlane’s CMOS chip lets electronics and diodes exist on a single chip, creating a less expensive, smaller product. This proximity allows the chip to communicate and generate information more quickly. A first generation of the chip has already been fabricated and awaits testing at the Spallation Neutron Source (SNS) at ORNL.

“I’m hoping it will show that I can, with their scintillator, measure incoming neutrons. They have specific levels that they look at for their imaging and I really want to see whether we can measure their entire range,” McFarlane said.

If testing with the SNS yields positive results, McFarlane is hoping to test her chip against commercial silicon photomultiplier arrays for efficiency and full range detection.