Scientists seek new physics using ORNL's intense neutrino source

June 17, 2016

OAK RIDGE, Tenn., June XX, 2016--Soon to be deployed at the Department of Energy's Oak Ridge National Laboratory is an experiment to explore new physics associated with neutrinos. The Precision Oscillation and Spectrum Experiment, or PROSPECT, is led by Yale University and includes partners from 14 academic and governmental institutions. The DOE High Energy Physics program will support the experiment at the High Flux Isotope Reactor (HFIR), a DOE Office of Science User Facility at ORNL. The neutrino, the subject of a 2015 Nobel Prize, remains a poorly understood fundamental particle of the Standard Model of particle physics.

These electrically neutral subatomic particles are made in stars and nuclear reactors as a byproduct of radioactive decay processes. They interact with other matter via the weak force, making their detection difficult. As a result of this elusiveness, neutrinos are the subject of many interesting and challenging detection experiments, including PROSPECT.

"Unique capabilities of ORNL will enable us to broaden the understanding of neutrino properties," said David Dean, director of ORNL's Physics Division. "The expansion of neutrino experiments at Oak Ridge National Laboratory is a win for the lab because we have a new scientific focus area, and a win for the scientific community because ORNL has unique neutrino sources that physicists will utilize to explore neutrino science."

It turns out that the two DOE Office of Science User Facilities for neutron scattering also produce, in addition to neutrons, a copious supply of neutrinos as a byproduct. These two sources are the Spallation Neutron Source, which delivers pulsed neutron beams, and HFIR, which provides continuous neutron beams. PROSPECT will be the first experiment at HFIR to detect neutrinos emitted from the reactor.

In development for more than 3 years, the PROSPECT experiment has 68 collaborators, including 14 from ORNL. Scientists will extract information about neutrino oscillations--transmutations of electron neutrino, muon neutrino and tau neutrino "flavors" from one to another. Specifically, they want to find out if neutrino oscillations occur over short distances (less than 65 feet). Neutrino oscillations have not been observed at these distances. Observing neutrino oscillations at these distances, coupled with PROSPECT's other objectives of high-precision measurements of the neutrino flux and spectrum from HFIR, could reveal the existence of a fourth neutrino flavor that does not interact via the weak force, a "sterile neutrino." Seeing this new particle would necessitate revising the Standard Model, which describes elementary particles and the forces that govern them.

The process to select the location of PROSPECT was competitive; HFIR and other U.S. research reactor sites were assessed. "We have been working for over three years to ensure that the experiment is located at HFIR," said Chris Bryan, who manages experiments at HFIR for ORNL's Research Reactors Division. These efforts include installing a 30-ton detector system (with shielding) in an operating research reactor building as close as 21 feet to the reactor core without affecting HFIR's primary missions of neutron scattering research, isotope production and testing of irradiated materials. "We have been actively engaged with ORNL's Physics Division, the first line for data gathering as well as ongoing care of the neutrino detector at HFIR," he added.

The ORNL-site principal investigator for the project, physicist Alfredo Galindo-Uribarri, said reviewers determined HFIR was the best reactor for short-baseline physics. "As one of the best-studied reactors, its behavior is very well understood," he said. "The research reactor has the most compact core of any reactor and burns highly enriched uranium. The fission products decay to form neutrinos. Particles start out as electron neutrinos and then change to muon and tau forms." Reactor neutrino detection at HFIR necessitates a detailed understanding of background radiation fields. Researchers at ORNL have been engaged in detailed measurements to understand the sources of background production at HFIR and demonstrate that reactor-produced neutron backgrounds can be suppressed with judiciously chosen shielding material.

Near the reactor, experimenters will place a 15-foot-high movable detector. They will fill it with 3 tons of liquid scintillator to detect the flash produced when a neutrino combines with a proton to form a positron (or anti-electron) and a neutron. A prototype detector has been built at ORNL for tests in preparation for the arrival of PROSPECT's detection instrument, now under construction at Yale. That instrument will be deployed at ORNL's famous research reactor before data collection begins next year.
ORNL's collaborators on PROSPECT are George Barclay, John Cunningham, Geoffrey Deichert, Michael Febbraro, Brennan Hackett, Charlie Havener, Blaine Heffron, James Matta, Paul Mueller, Elisa Romero-Romero, Robert Varner, Chris Bryan, David Dean and Alfredo Galindo-Uribarri.

Besides Yale and ORNL, PROSPECT's partners are Drexel University, Georgia Institute of Technology, Illinois Institute of Technology, Le Moyne College, National Institute of Standards and Technology, University of Tennessee-Knoxville, Temple University, Brookhaven National Laboratory, Lawrence Livermore National Laboratory, University of Waterloo, College of William and Mary and University of Wisconsin-Madison.

UT-Battelle manages ORNL for DOE's Office of Science. The single largest supporter of basic research in the physical sciences in the United States, the Office of Science is working to address some of the most pressing challenges of our time. For more information, please visit Dawn Levy

CAPTION/CREDIT: The High Flux Isotope Reactor, a Department of Energy Office of Science User Facility that creates continuous neutron beams, is the site of a new neutrino experiment. Yale-led PROSPECT will probe neutrinos formed as a byproduct of radioactive decay processes. Image credit: Oak Ridge National Laboratory, U.S. Dept. of Energy; photographer Genevieve Martin

DOE/Oak Ridge National Laboratory

Related Neutrinos Articles from Brightsurf:

Big answers from tiny particles
A team of physicists led by Kanazawa University demonstrate a theoretical mechanism that would explain the tiny value for the mass of neutrinos and point out that key operators of the mechanism can be probed by current and future experiments.

Physicists cast doubt on neutrino theory
University of Cincinnati physicists, as part of an international research team, are raising doubts about the existence of an exotic subatomic particle that failed to show up in twin experiments.

Exotic neutrinos will be difficult to ferret out
An international team tracking the 'new physics' neutrinos has checked the data of all the relevant experiments associated with neutrino detections against Standard Model extensions proposed by theorists.

Excess neutrinos and missing gamma rays?
A new model points to the coronoe of supermassive black holes at the cores of active galaxies to help explain the excess neutrinos observed by the IceCube Neutrino Observatory.

Where neutrinos come from
Russian astrophysicists have come close to solving the mystery of where high-energy neutrinos come from in space.

Where did the antimatter go? Neutrinos shed promising new light
We live in a world of matter -- because matter overtook antimatter, though they were both created in equal amounts when our universe began.

Strongest evidence yet that neutrinos explain how the universe exists
New data throws more support behind the theory that neutrinos are the reason the universe is dominated by matter.

Why didn't the universe annihilate itself? Neutrinos may hold the answer
New results from an experiment called T2K suggest that physicists are closer than ever before to answering a major mystery: Why didn't the universe annihilate itself in a humungous burst of energy not long after the Big Bang?

T2K insight into the origin of the universe
Lancaster physicists working on the T2K major international experiment in Japan are closing in on the mystery of why there is so much matter in the universe, and so little antimatter.

Radar and ice could help detect an elusive subatomic particle
A new study published today in the journal Physical Review Letters shows, for the first time, an experiment that could detect a class of ultra-high-energy neutrinos using radar echoes.

Read More: Neutrinos News and Neutrinos Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to