September 7, 2012
First Installation Phase Of NOvA Neutrino Experiment Underway
April Flowers for redOrbit.com - Your Universe Online
The first block of what will be the largest, most advanced neutrino experiment in North America is now being installed in Minnesota.
On track to come online in 2013, the NuMI Off-Axis Appearance experiment — NOvA for short — will study the properties of neutrinos, such as their masses, and investigate whether they helped give matter an edge over antimatter after both were created in equal amounts in the Big Bang.
“This is a significant step toward a greater understanding of neutrinos,” said Marvin Marshak, NOvA laboratory director and director of undergraduate research at the University of Minnesota. “It represents many months of hard work on the part of the whole NOvA collaboration.”
In the Standard Model of particle physics, neutrinos are elementary particles, basic building blocks, if you will. They are almost massless, and they interact so rarely with other matter than they can move straight through hundreds of miles of solid rock.
The Standard Model is a theory concerning the electromagnetic, weak, and strong nuclear interactions, which mediate the dynamics of the known subatomic particles.
NOvA will study a beam of neutrinos streaming about 500 miles through the Earth from the U.S. Department of Energy's Fermi National Laboratory near Chicago to a large detector in Ash River, Minnesota. The particles, generated in what will be the most powerful neutrino beam in the world, will make the trip in less than three milliseconds.
Installation crews will use a 750,000-pound pivoter machine to lift the first, of 28, 417,000-pound block and put it into place at the end of the 300-foot-long detector hall. The delicate process may take multiple days.
Each of those 28 blocks measures 51 by 51 by 7 feet and is made up of 384 plastic PVC modules. About 170 students from the University of Minnesota built them, stringing them with optical fibers and attaching their endcaps.
Scientists and engineers at the Department of Energy´s Argonne National Laboratory developed the machine that glues modules into blocks. Scientists and engineers at Fermilab developed the pivoter machine and assembly table.
“About a dozen scientists, engineers and technicians from Fermilab and Argonne have been up to Ash River multiple times in the past year to make this thing happen,” said Rick Tesarek, Fermilab physicist and NOvA deputy project leader. “They´re part of a team of over a hundred collaborators who have been actively working on the experiment.”
The crews will fill the newly installed block with liquid scintillator. When the neutrinos interact with the liquid, they will produce charged particles that will release light, which the optical fibers will detect. The fiber will carry the signal to electronics, which will record the neutrino event.
There are three flavors of neutrinos, each associated with a different elementary particle: electron, muon and tau. Three different types of neutrinos oscillate between these flavors, spending a different fraction of their lives as each flavor.
“Everyone´s been watching to see which experiment will make the next big step in uncovering the properties of neutrinos,” said Mark Messier, Indiana University physicist and co-spokesperson of the NOvA experiment. “The NOvA experiment should be it. It is uniquely positioned to be the first experiment to determine the ordering of the masses of the three neutrinos.”
Groundbreaking for the NOvA facility started in May 2009 and crews completed the building, a laboratory of the University of Minnesota´s School of Physics and Astronomy, this spring.
There will be two detectors, the one in Minnesota and a 330-metric-ton detector at Fermilab, used to look for changes in the neutrino beam as it travels. The far detector is scheduled to begin taking data in 2013 and to be completed in early 2014.
The Fermilab neutrino beam is being upgraded right now during a yearlong accelerator shutdown. This upgrade will be crucial to the experiment, as Fermilab will increase the power of the beam by a factor of two from 320 kilowatts to 700 kilowatts. NOvA experimenters expect eventually to study a sample of about 100 neutrino events during six years of operation.