Neutrinos are one of the most abundant particles in the universe, but we still know very little about them. Every second, hundreds of billions of neutrinos pass through our bodies – only rarely making their presence known. Yet neutrinos are crucial for the explosion mechanism of supernovae and thus the dispersal of a large fraction of the elements around the universe – including our home planet and us.
Further, a detailed understanding of neutrinos may be key to understanding the origin of matter-antimatter asymmetry of the universe. A key tool to the detailed understanding of neutrinos is the measurement of the transformation of one type of neutrino to another. We do this by creating one type of neutrino somewhere and measuring it some distance away from its creation point to see if it has changed type. The quantum mechanical interference effect, called neutrino oscillations, is responsible for the change in neutrino type. The probability of conversion depends on the distance away from the creation point where one makes a measurement, and on the energy of the neutrino.
Making a precise measurement of the neutrino energy is crucial to making high-sensitivity measurements of neutrino oscillation phenomena. The United States is hosting a large international project called DUNE (Deep Underground Neutrino Experiment) to make the most detailed neutrino oscillation measurements yet.
DUNE’s detectors are to be constructed of liquid argon. At the neutrino energies employed by DUNE, neutrinos create many particles in our detectors. Measuring the neutrino energy means making a precise measurement of the energies and momenta of other generated particles. The most challenging of these particles are the neutrons.
The Early Career Award (ECA) made the first measurements of high energy neutrons in argon possible at DOE’s LANSCE facility at Los Alamos National Laboratory. This unique facility combined with an argon detector built with support from the ECA was the magic combination to make these challenging measurements a reality.
Christopher M. Mauger is an associate professor in the Department of Physics & Astronomy at the University of Pennsylvania, formerly a staff scientist at the U.S. Department of Energy Los Alamos National Laboratory.
SUPPORTING THE DOE SC MISSION:
The Early Career Research Program provides financial support that is foundational to early career investigators, enabling them to define and direct independent research in areas important to DOE missions. The development of outstanding scientists and research leaders is of paramount importance to the Department of Energy Office of Science. By investing in the next generation of researchers, the Office of Science champions lifelong careers in discovery science.
For more information, please go to the Early Career Research Program.
THE 2010 PROJECT ABSTRACT:
Design of the Near Detectors and Optimization of Water and Ice Targets for Fine‐Grained Tracking Detectors for the Fermilab Long‐Baseline Neutrino Experiment
The Long‐Baseline Neutrino Experiment (LBNE) is actively being developed in the U.S. This project will employ a neutrino beam at Fermilab aimed at a far site—most likely the proposed Deep Underground Science and Engineering Laboratory in Lead, South Dakota, (currently being developed by the National Science Foundation)–to search for neutrino transitions from one type to another. LBNE will measure these transitions with unprecedented sensitivity, which will reveal key properties of these elusive fundamental particles.
These experiments work by observing the rate of neutrino interactions in "near" detectors close to the beam and in "far" detectors 100's of kilometers away to see if any neutrinos appear (or disappear) in between; the (dis)appearance is evidence that the neutrinos oscillated from one type to another.
The PI proposes to lead the development of the suite of near detectors required to optimize the sensitivity of the LBNE project. The PI will focus particularly on using the near detectors to measure neutrino processes that contribute to the background in the far detector. In addition, the PI will develop liquid and solid water targets for a fine‐grained tracking near detector.
B. Bhandari et al., CAPTAIN Collaboration, “First Measurement of the Total Neutron Cross Section on Argon between 100 and 800 MeV.” Phys. Rev. Lett. 123, 042502 (2019). [DOI:10.1103/PhysRevLett.123.042502]
For more information on neutrinos and DOE's research in this area, please go to "DOE Explains...Neutrinos."
Additional profiles of the 2010 Early Career Research Program award winners can be found at: https://www.energy.gov/science/listings/early-career-program.
The Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, please visit www.energy.gov/science.
Sandra Allen McLean is a Communications Specialist in the Office of Science, firstname.lastname@example.org.