Neutrino factory could be right prescription to see theta₁₃

Scientists would use a neutrino factory to smash protons into a target, collect muons resulting from the collision, cool them to similar energies and momenta, accelerate them and let them decay into neutrinos.

Most neutrino experiments running today have one thing in common: They are trying to pin a number on a parameter known as theta₁₃, or θ₁₃.

This number may simply equal zero. But if it doesn't, it might tell physicists something about the role of neutrinos in the imbalance between matter and antimatter in the universe, the reason we exist.

Physicists have put tighter and tighter constraints on the number. A recent result from the MINOS collaboration at Fermilab allowed them to push the limits previously set by the CHOOZ experiment in France. If θ₁₃ is very small, it could take a new type of neutrino experiment to find it: a neutrino factory.

Sixty-four physicists from 30 American and European institutions met at Fermilab in early April as part of an international design study with a goal of creating a design report for a neutrino factory in the next few years. The report will include a recommended design and cost estimate and will open the door for a laboratory to propose to build a neutrino factory.

Neutrinos come in three flavors and in three masses. A neutrino of one mass is actually a mixture of the three flavors. It spends some portion of its time as an electron neutrino, some as a muon neutrino and some as a tau neutrino. Switching from flavor to flavor is called oscillation.

Physicists think that all three masses of neutrinos follow this pattern, each with a different recipe for how much time it spends as each flavor. But they have not observed every possible type of oscillation.

Theta₁₃ is a measure of how often electron neutrinos oscillate into tau neutrinos. If this type of oscillation happens at all, θ₁₃ will be larger than zero. But if θ₁₃ is a very small number, today's neutrino experiments may not have the precision to find it.

"Then the neutrino factory looks interesting," said Fermilab physicist Alan Bross, co-spokesperson for the Neutrino Factory and Muon Collider collaboration.

"It's like a new pair of glasses," said Vladimir Shiltsev, director of Fermilab's Accelerator Physics Center. "So you can read what Mother Nature wrote in her book."

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-- Kathryn Grim

Fermilab to host annual Farmers' Picnic Saturday

George VanVleet (left center), visited his farm house in its current location at Site 56 on Eola Road during the 2009 Farmers' Picnic. He was joined by his son, John, his grandson, Adam, and his wife, Betty.

Fermilab will host its 13th annual Farmers' Picnic at noon on Saturday, May 1, in Kuhn Barn. The annual potluck-style celebration usually attracts about 100 guests most of whose family farms used to occupy the Fermilab site. For more information, view the invitation (pdf) or call (630) 840-8640.

Learn more about the farms or families that once occupied the Fermilab site.

Evidence grows for tetraquarks

From Physicsworld.com,
April 27, 2010

The existence of a new form of matter called a tetraquark has been given further support by the re-analysis of an experiment that has baffled particle physicists for the past two years.

In 2008 researchers on the BELLE experiment at the KEK Laboratory in Japan looked at how an excited state of the meson "bottomonium" decayed and were very surprised to find that one particular decay mode was much more common than expected.

Now, physicists in Germany and Pakistan have proposed an extraordinary explanation - instead of producing bottomonium, the experiment had created a new particle containing four quarks. If such tetraquarks do exist, it would lead to an extended quark model of exotic particles. It would also give physicists a deeper understanding of quantum chromodynamics (QCD) - the Standard Model's theory of quarks and the strong force that binds them together.

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