Hunting Cosmic Ghosts

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Neutrinos are the ghosts of the universe. They pass through all matter and travel at near the speed of light. And some begin with a star’s violent death.Image courtesy of Pacific Northwest National Laboratory

Neutrinos are the ghosts of the universe. They pass through all matter and travel at near the speed of light. And some begin with a star's violent death.

"The ghosts of the universe." They pass through you, me, and, in fact, all matter. They travel at near the speed of light. They morph into different forms. And some begin with the violent death of a star.

These "ghosts" are subatomic particles called neutrinos, and Alysia Marino has spent her career hunting them down and learning their secrets, thanks in part to the U.S. Department of Energy (DOE). Alysia received five years of funding from a 2010 Early Career Research Program Award given by DOE's Office of Science.

Her interest in neutrinos began with doctoral work at the University of California at Berkeley and through several postdoctoral fellowships. In January 2009, she moved to the University of Colorado at Boulder to teach and research. A year later, she received the DOE early career award.

"Winning the early career award has been a great honor that has let me expand the direction of my research," said Alysia, now an associate physics professor at Colorado.

With the award's five years of funding, Alysia focused first on the characteristics and behavior of neutrinos. Working at a massive neutrino generator and detector in Japan, she was part of the team that discovered a new way in which neutrinos change forms during flight. Neutrinos come in three forms: muon, electron, and tau. Each form is named for the particles it produces when it reacts. Conventional wisdom held that muon neutrinos could change into tau neutrinos.

But was that it? Was that the only transformation muon neutrinos could make?

In 2011, Alysia and her colleagues saw the first signs that muon neutrinos could also turn into electron neutrinos. By 2013, with 3.5 times more data, the team definitively showed the transformation.

The transformation may help explain why the universe formed as it did. The observable universe is made almost entirely of matter, but moments after the Big Bang, the universe contained as much antimatter as matter. Physicists think that yet-to-be-determined forces are responsible for matter's prevalence. The discovery by Alysia and her colleagues at the Japan Proton Accelerator Research Complex shows how neutrino transformations may be part of those hidden forces.

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Alysia Marino is spending her career hunting down neutrinos and learning their secrets.Photo courtesy of the University of Colorado Boulder

Alysia Marino is spending her career hunting down neutrinos and learning their secrets.

In addition to studying the nuances of neutrinos, Alysia has designed new ways to detect the smaller-than-an-atom particles. At DOE's Fermi National Accelerator Laboratory in Illinois, Alysia and her colleagues designed and built muon detectors to sit close to the neutrino beam's origin. There, the detectors provide data that helps scientists better control the experiments. Since the summer of 2014, Alysia and her colleagues have been tuning their detectors. Once tuned, the instruments will get a serious workout as part of the Deep Underground Neutrino Experiment.

"It’s been exciting to come up with a new idea, build it, and deploy it," said Alysia.

Her attitude carries from the lab to the classroom. Alysia wants her physics students to try new ideas. She re-established a seminar program for graduate students that showcases work done throughout the University of Colorado at Boulder. The seminars attract students and scientists from the university as well as people from nearby institutions. "It provides a lot of opportunities beyond the halls of the physics department and shows students things that can't be seen on a website or program brochure," said Alysia.

Her early career award has given her funding, but to Alysia, the award's greatest value was the freedom to capture and study neutrinos. She is now working on several projects related to those ghostly particles.

All ghosts have their secrets, and thanks to her early career award, Alysia is revealing them, and helping to solve the deep mysteries of the universe.

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Kristin Manke is a Communications Specialist at Pacific Northwest National Laboratory on detail to the U.S. Department of Energy's Office of Science,