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Physicists Receive Prestigious DOE Honor for Young Faculty

Two “creative and exceptional researchers” study particles: one dark, one light

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May 8, 2014 | by Megan Fellman

EVANSTON, Ill. --- Two young Northwestern University physicists -- Eric Dahl and Nathaniel Stern -- have been selected by the Department of Energy’s (DOE’s) Office of Science to receive significant research funding as part of the DOE’s highly selective Early Career Research Program.

Dahl and Stern, both assistant professors of physics and astronomy in the Weinberg College of Arts and Sciences, are among only 35 scientists at U.S. universities and national laboratories to receive the honor this year.

Each will receive $750,000 over five years. With this support, Dahl will build novel instruments for the detection of dark matter particles, and Stern will investigate quantum phenomena in two-dimensional materials.

The five-year grants bolster the nation’s scientific workforce by providing support to exceptional researchers during the crucial early career years, when many scientists do their most formative work.

“Without this award, it is unlikely I’d be able to pursue this project,” Dahl said. “There’s an element of risk to it, as there is with any untested idea, but this is how scientific advances are made -- by trying new things. Getting this opportunity -- to go after the next new thing -- is what any young scientist dreams about. I can't wait to make it happen.”

“I feel truly honored to be selected for this award,” Stern said. “Progress in nano-scale materials science is rapid, promising to change our outlook on what is possible when we have ultimate control of crystals at the atomic scale. The generous support of the DOE allows me the opportunity to design new quantum environments never explored before.”

Eric Dahl

Dahl builds specialized particle detectors to try to see the nearly invisible dark matter particles that dominate our galaxy. There is a huge body of gravitational evidence that most of the matter in the universe is “dark,” he said. From the motions of individual galaxies to the big bang and the expansion of the universe, all indications are that there is six times more matter than can be accounted for by known particles.

So far nobody has unambiguously seen a dark matter particle, though many groups are trying. The DOE award will support Dahl’s development of a new type of detector: a scintillating xenon bubble chamber that combines the strengths of the current leading technologies. The basic detector is a liquid heated past its boiling point so that certain particle interactions, including those from dark matter, will create bubbles of boiled vapor. When the liquid is xenon, these interactions also create flashes of light called scintillation.

By observing both the bubble and the light output from the bubble formation, Dahl and his team will have an unprecedented ability to distinguish dark matter interactions from more mundane events, such as natural radioactivity. Lower backgrounds translate to greater sensitivity to dark matter and, hopefully, a dark matter discovery, Dahl said.

The discovery of dark matter would open the door to an entirely new type of astronomy -- shedding light on how our galaxy formed in the first place. “On the other hand, if we see nothing, we may need to revisit our fundamental understanding of the universe and Einstein’s theory of gravity,” Dahl said. “Either way, the science impacts are huge.”

Nathaniel Stern

Stern’s research focuses on developing methods to use light to study the unique properties of nano-scale systems that emerge from quantum physics. When materials are reduced to this fundamental size limit, new and often counter-intuitive behaviors appear that can be probed and controlled with high precision using light.

Under the DOE award, Stern will study how quantum mechanical particles of light -- photons -- can interact with crystal sheets as thin as a single layer of atoms. By tinkering with how these materials “see” the photons, environments sharing aspects of both light and physical matter can be created that have never been explored before, Stern said. This work will combine several electrical and optical measurement techniques with his group’s experience in microfabrication to design new methods of controlling low-dimensional matter using single photons.

“By connecting diverse materials with light, researchers can envision new approaches to electronic circuits, energy harvesting and tracking quantum information encoded in solid-state materials,” Stern said. “Progress in this approach promises to change our outlook of what applications are possible when we simultaneously control both light and matter at the smallest length scales.”

A list of the 35 awardees, their institutions and titles of research projects is available on the Early Career Research Program website.
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