A neutrino is detected by the charged particles that result when one collides with an atom of the mineral oil, doped with fluorescing molecules to create a scintillator. Credit: Reinar Hahn/Fermilabīoth detectors are constructed of layers of PVC channels, filled with mineral oil, creating a favorable environment for seeing neutrinos interact. Vahle is at Fermilab as an Intensity Frontier Fellow. Patricia Vahle, associate professor of physics at William & Mary, works on a detector prototype set up before the actual NoVA experiment. "Then we look in the far detector to uncover the oscillation properties." "We always have a detector close by, so we can figure out the properties of the neutrino beam and how the detectors work before any oscillations happen," Vahle explained. A near detector, the third component, is located at Fermilab. NOvA is what physicists call a long-baseline experiment because the neutrino beam must travel some 500 miles to the far detector in Ash River, Minnesota. A particle accelerator sends a beam of neutrinos (known as the NuMI beam) aimed at two detectors, one near and one far. Like most neutrino experiments, NOvA has three components. "I personally am a little surprised that we were able to find them in as small a section of the detector as we did." "We certainly expected to see neutrinos-and we're seeing them where we expected to see them," Vahle said.
Vahle is one of a group of William & Mary physicists working on NOvA, which made the news in February after the scientists saw neutrinos even before they were finished building the experiment apparatus.
Patricia Vahle, associate professor of physics, is spending a year at Fermilab as an Intensity Frontier Fellow and her post-doctoral researcher, Alex Radovic, is resident at Fermilab. Three of the current neutrino experiments at Fermilab-MINOS/MINOS+, MINERvA and NOvA-examine different properties of neutrinos emitted by a common source, the NuMI beam. In the U.S., the Department of Energy's Fermi National Accelerator Laboratory outside Chicago is home to a number of neutrino experiments and therefore home away from home for some of William & Mary's physicists.
For instance, William & Mary physicists Robert McKeown and Wei Wang collaborate with scientists at the Daya Bay neutrino experiment in China, helping to nail down a key measurement, known as the "mixing angle" θ13, pronounced "theta one-three," in 2011. Want to understand galaxy clustering? Interested in why the universe is dominated by matter? It doesn't matter understanding how neutrinos operate is essential to taking any number of next steps in new physics.īecause these subatomic particles are so important on so many levels, there are many neutrino experiments going on and William & Mary physicists are involved in a number of them. Scientists have learned a lot about stars (including our own sun) by studying neutrinos, and there is a lot more to learn about the cosmos. Physicists have long understood that the path to learning more about just any aspect of energy or matter leads, sooner or later, through a cloud of these mysterious and ubiquitous subatomic particles. Particle physicists talk about "mixing" to describe the weird morphing of neutrino masses and flavors the mixing phenomenon is the focus of many neutrino experiments. It gets even more complicated: Neutrinos have mass, but the mass and the flavors don't necessarily correspond. Fermilab explains oscillation by asking us to imagine a sports car, changing into a bus or minivan as it goes down the highway, then changing back to a sports car. They oscillate-change flavors- in midflight. They come in three "flavors"-electron, muon and tau. They almost never interact with matter, a property that makes neutrinos a challenge to study. There is more to neutrinos than the detritus of reactions they are interesting little things in their own right. When a star goes supernova, the process generates an enormous spurt of neutrinos. The fusion furnace of our sun pumps out neutrinos.
The Big Bang produced neutrinos-particles that are still zooming through space yet today.
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