LSU Physicists Contribute to Nobel Prize Winning Research FOR IMMEDIATE RELEASE October 8, 2015 Baton Rouge - The 2015 Nobel Prize in Physics was recently awarded to Takaaki Kajita of the University of Tokyo and Arthur McDonald of Queens University in Canada for the discovery of neutrino oscillations, which shows that neutrinos — a type of sub-atomic particles — have mass. LSU Professor of Physics Thomas Kutter and his group of researchers were members of the Sudbury Neutrino Observatory, or SNO Collaboration, led by McDonald, which made the key measurements by observing neutrinos from the Sun. In the case of solar neutrinos, the SNO team solved the 30-year-old puzzle of the “missing solar neutrinos” in their underground laboratory two kilometers below the surface of the Creighton Mine in Sudbury, Ontario. The scientists discovered that neutrinos change on the way from the Sun to Earth, which proves that neutrinos have mass. This modifies the long-held Standard Model of particle physics. The discovery provides insight into fundamental processes governing neutrinos and potential new discoveries into the universe. LSU’s Kutter co-authored, while working at the University of British Columbia, two of the three papers that document the discovery of neutrino oscillations, which the Nobel committee deemed essential [1, 2]. “It has been an honor to be a member of the SNO Collaboration and to participate in this historic research, which required meticulousness in every step along the way,” Kutter said. Kajita was the leader of the Super-Kamiokande Collaboration, which made similar measurements by looking at neutrinos generated in the atmosphere of Earth. The Super-Kamiokande detector is currently also being used as a distant detector by the T2K experiment, which further explores neutrino oscillations by means of a man-made neutrino beam. Kutter, Martin Tzanov, assistant professor in the LSU Department of Physics & Astronomy, and their team of LSU post-doctoral researchers and students are members of the T2K collaboration and continue to make significant contributions to the measurement of neutrino oscillations and their properties. “We are very excited about Thomas’ contribution to this Nobel Prize winning work. This discovery expands our view of the universe and is a prime example of the caliber of research

taking place in the LSU College of Science,” said Cynthia Peterson, dean of the LSU College of Science and Seola Arnaud and Richard Vernon Edwards Jr. Professor. “On behalf of the college, I salute Thomas and all of the members of the SNO collaboration for such an outstanding achievement.” The awarding of the Nobel Prize for neutrino oscillations represents an important endorsement of the neutrino experiments led by the Nobel laureates, and the field of neutrino physics. This is also a great recognition of all the contributors, which include LSU faculty. The Nobel Prize in Physics is awarded by the Royal Swedish Academy of Sciences in Stockholm, Sweden. For more information about the 2015 Nobel Prize in Physics, visit http://www.nobelprize.org/nobel_prizes/physics/laureates/2015/press.html

Picture shows the SNO detector with Nobel medal overlaid. The dots are light sensitive devices (photomultipliers) used to detect light from neutrino interactions inside the (heavy) water of the detector. [picture credit: Roy Kaltschmidt, LBL]

1. Q.R. Ahmad et al (SNO collaboration), “Measurement of the Rate of νe + d → p + p +e-

Interactions Produced by 8B Solar Neutrinos at the Sudbury Neutrino Observatory”, Physical Review Letters 87, 071301 (13 August 2001)

2. Q.R. Ahmad et al (SNO collaboration), “Direct Evidence for Neutrino Flavor Transformation from Neutral-Current Interactions in the Sudbury Neutrino Observatory”, Physical Review Letters 89, 011301 (1 July 2002)