ANGIE RIEBE STAFF WRITER ASH RIVER — Every second 100,000 billion neutrinos pass right through you, and you’re never the wiser. The fundamental sub-atomic particles that are produced naturally from the sun and cosmic rays rarely interact with matter, and it’s likely that during your entire life, not even one neutrino will hit an atom in you. And while scientists have been studying neutrinos for a number of years via several experiments worldwide — including one in the Soudan Underground Mine — there is still much to be learned about this abundant and elusive miniscule particle. But with the help of the newest physics experiment in a remote area northeast of Orr, scientists are hoping to gain wisdom about this extremely common particle. o The $270 million NOvA project — which involves more than 200 scientists and engineers from 39 universities and laboratories in eight countries — will supplement work that has been accomplished at the MINOS experiment in Soudan, which launched in 2005. A celebration of the completion of the 14,000-ton NOvA detector in Ash River was held Thursday at the site. The event included tours of the lab and detector and a program featuring several speakers. The Ash River lab is operated by the University of Minnesota under a cooperative agreement with the U.S. Department of Energy’s Office of Science. The entire project is being funded by the federal government through a combination of stimulus money and an allocation from the DOE. The detectors were built mostly by the faculty, staff and students from the U of M’s School of Physics and Astronomy. More than 700 students worked on the module assembly facility on the Twin Cities campus. However, the vast majority of subcontractors and workers who were employed to build the $40 million detector were from the area. The local economic impact includes: • 80 full-time construction jobs created to build the far detector laboratory. • 47 full-time technicians were hired to help assemble the detector. • Wayne Transport delivered 409 takers of oil. An average of 150 modules per week were filled over 72 weeks. The tankers were kept heated in the winter so the oil was at room temperature when filling. During the almost three years of building the detector, “we spent over $5 million just in wages,” said Bill Miller, lab supervisor. “Dozens and dozens of workers from northeast Minnesota” participated in the building, said Richard Beeson, chair of the Board of Regents at the U of M. o Why Ash River? One reason is Fermilab’s neutrino beam, used in the MINOS project, is already pointed in that direction, said Chishom high school science teacher Cory Kolodji, who was giving tours of the lab Thursday. MINOS (which stands for Main Injector Neutrino Oscillation Search) has operated on a theory that links neutrinos mass to oscillations of the particles. The experiment has collected data on what happens when mueon neutrinos (one of three kinds of the particle) oscillate over a distance. Neutrinos also come in the form of electron neutrinos and tau neutrinos, and they change forms as they travel. NOvA (which stands for NuMI Off-axis electron Neutrino Appearance) will look specifically at the rare transition of muon neutrinos to electron neutrinos. (NuMI is an acronym for Neutrinos from the Main Injector, and “v” is a symbol for neutrino.) An experiment on the tau neutrino is already taking place in Italy. NOvA is designed to answer several fundamental questions in neutrino physics, including: • Can we observe the oscillation of muon neutrinos to electron neutrinos? • What is the ordering of neutrino masses (which of the three types has the most and least)? Normally, the beam of neutrinos is pointed directly at the detector. But in the case of the NOvA detector, it is positioned just “off-axis” of the beam to capture those specific particles. The distance from Fermilab is also important to allow enough time for the neutrinos traveling nearly the speed of light to oscillate. And the detector must be large enough to “see” the neutrinos and take detailed pictures of neutrino interactions. Professor Mark Messier of Indiana University explained the importance of the NOvA experiment. “We know they (neutrinos) have mass, but we don’t know what. We know there are three kinds, but we don’t know which is the heaviest.” The project will assist “to unlock these questions of this most abundant particle” as part of a worldwide program to study neutrinos, he said. Other experiments have taken place in Japan, China and Italy. NOvA will be “part of a global community,” he said. Thursday was a day to “celebrate a lot of hard work” that has taken place since ground-breaking at the Ash River site in May 2009, said Marvin Marshak, director of the laboratory and one of the people instrumental in starting the neutrinos studies in Soudan. o The NOvA experiment consists of two particle detectors 500 miles apart that measure neutrinos manufactured at Fermi National Accelerator Laboratory (Fermilab), near Chicago, which manages the project. Fermilab generates a beam of neutrinos through a process that involves smashing protons into a graphite target, steering them with magnets into the beam and filtering out the non-neutrinos. The beam of neutrinos travels through the smaller “near” detector at Fermilab’s gigantic 14,000-ton “far” detector in Ash River. Billions of the particles are shot out every 1.7 seconds on the trip that takes less than three milliseconds to accomplish. Because neutrinos rarely interact with matter, they travel straight through the earth on that journey, and very few will make their presence known in the “far” detector. Scientists expect only a tiny fraction of neutrinos will be detected — likely only a one or two a month. But those scarce occurrences will provide big answers to science. The Ash River lab director’s findings “will make important contributions to our knowledge of these particles,” according to Marshak. In the deep vacuum of space, there are 330 million neutrinos in every cubic yard. Because of their enormous abundance, they have an important influence on the structure of the universe, and studying them could yield crucial information about the early moments of the universe, according to scientists. o Why Ash River? One reason is Fermilab’s neutrino beam, used in the MINOS project, is already pointed in that direction, said Chishom high school science teacher Cory Kolodji, who was giving tours of the lab Thursday. MINOS (which stands for Main Injector Neutrino Oscillation Search) has operated on a theory that links neutrinos mass to oscillations of the particles. The experiment has collected data on what happens when mueon neutrinos (one of three kinds of the particle) oscillate over a distance. Neutrinos also come in the form of electron neutrinos and tau neutrinos, and they change forms as they travel. NOvA (which stands for NuMI Off-axis electron Neutrino Appearance) will look specifically at the rare transition of muon neutrinos to electron neutrinos. (NuMI is an acronym for Neutrinos from the Main Injector, and “v” is a symbol for neutrino.) An experiment on the tau neutrino is already taking place in Italy. NOvA is designed to answer several fundamental questions in neutrino physics, including: • Can we observe the oscillation of muon neutrinos to electron neutrinos? • What is the ordering of neutrino masses (which of the three types has the most and least)? Normally, the beam of neutrinos is pointed directly at the detector. But in the case of the NOvA detector, it is positioned just “off-axis” of the beam to capture those specific particles. The distance from Fermilab is also important to allow enough time for the neutrinos traveling nearly the speed of light to oscillate. And the detector must be large enough to “see” the neutrinos and take detailed pictures of neutrino interactions. o Constructing the NOvA detector — which is as wide as a basketball court and twice as long — was quite a feat. The structure is the largest free-standing plastic structure in the world, said University of Minnesota Dean Ron Crouch. It consists of 10,782 extruded PVC modules, each which weighs more than 1,100 pounds. The modules are threaded with particle detecting optic fibers, filled with scintillator oil, and outfitted with electronics. The detector contains a total of 2.68 million gallons of scintillator oil which lights up when a particle passes through it. Fibers conduct light to photo sensors and an array of electronics records each particle. The light is “amplified and turned into an electronic signal,” which is then recorded to the computers, Kolodji said. It is far-advanced electronics compared to the older MINOS system, he said. o NOvA is scheduled to run for at least six years. The very first electron neutrino was detected last December, before the detector was even completed. “Everything was designed to run remotely from Fermilab,” Miller said. “We of course do get visiting scientists, but now that we have completed the detector the number will be reduced.” A crew of about six will remain to operate the detector, he said. It will cost approximately $1.5 million per year to operation the detector, said Miller. “About $500,000 of that is just the cost of electricity to run the detector and the NOvA Far Detector Lab,” he said. “Basically, of course like everyone, we order things online to be delivered,” but the majority of operations costs are spent locally, including to North Star Electric, Miller said. “Roughly 85 percent of the budget is spent on salaries and electricity.” Looking back and going forward, NOvA is “a testament to science and engineering,” Marshak said. Dr. Brian Herman, vice president of research at the University, said the project shows what collaborative work can accomplish. Dr. Regina Rameika, head of the Fermilab Neutrino Department, said NOvA is its “flagship experiment.” Neutrinos are the future of Fermilab,” she said. And “the future is bright.”
Posted on: Sun, 27 Jul 2014 22:48:40 +0000
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