Neutrinos could be the key to unlocking the mysteries of the universe

T2K

A large international group of physicists, including a team based at the University of Sheffield, has reported new experimental results that show a difference in the way neutrinos and antineutrinos behave. The results could help us understand why there is so much matter in the universe, but very little antimatter.

Neutrinos are fundamental particles that make up our Universe and are among the least understood. Yet every second around 50 trillion neutrinos from the Sun pass through your body.

Understanding whether neutrinos and antineutrinos behave differently is important, because if all types of matter and antimatter behave in the same way, they should have completely wiped each other out shortly after the Big Bang.

To explore the changes in neutrinos, known as oscillations, the T2K experiment fires a beam, which can switch from neutrinos to antineutrinos, from the J-PARC laboratory on the eastern coast of Japan. When the beam reaches the Super-Kamiokande detector, 295 km away, scientists then look for a difference in the oscillations of neutrinos and antineutrinos.

LTProfessor Lee Thompson, Professor of Experimental Particle Physics in the University of Sheffield’s Department of Physics and Astronomy is one of the international T2K team and has been working on the project from its inception in 2006. He said, “The Super-Kamiokande detector records the products of the interactions of the neutrinos or antineutrinos and so allows us to study the ways in which the neutrinos and antineutrinos oscillate.

“What the T2K results are indicating is that antineutrinos do not oscillate in the same way as neutrinos. It looks as though there could be a difference, or asymmetry, between the behaviour of matter and antimatter.”

The results indicate a high rate of electron neutrino appearances compared to electron antineutrinos – higher than first expected.

Dr Morgan Wascko, international co-spokesperson for the T2K experiment from the Department of Physics at Imperial, said: “The current T2K result shows a fascinating hint that there's an asymmetry between the behaviour of neutrinos and antineutrinos, in other words an asymmetry between the behaviour of matter and antimatter. We now need to collect more data to enhance the significance of our observed asymmetry.”

Although this work is promising, there are still systematic uncertainties. Professor Thompson, with colleagues Dr Matthew Malek and Dr Susan Cartwright, are also part of an international team that is designing a next generation neutrino detector, Hyper-Kamiokande, or “HyperK”, which will much larger than Super-Kamiokande.

Professor Thompson noted, “Once the new HyperK detector is fully commissioned it will offer scientists in Sheffield and around the world, even greater insights into the behaviour of neutrinos and we are delighted to be partners in this incredible project.”

The T2K project is funded, in part, by the Science and Technology Facilities Council (STFC).

Notes to editors
T2K (Tokai-to-Kamioka) – an international experiment led by Japan and part funded by the UK’s Science and Technology Facilities Council (STFC) - will probe the strange properties of the enigmatic neutrino to unprecedented precision, by firing the most intense neutrino beam ever designed from the east coast of Japan, all the way under the country, to a detector near Japan’s west coast.
T2K involves an international team of around 500 physicists from 63 institutes in 11 countries including the UK, Japan, the US, Canada, France, and Switzerland. The UK T2K collaboration consists of scientists from Imperial College London (including the current International Co-Spokesperson Dr. Morgan Wascko), Lancaster University, the University of Liverpool, Oxford University, University of Sheffield, Warwick University, Queen Mary University of London, and the STFC’s Rutherford Appleton and Daresbury Laboratories.

STFC
The Science and Technology Facilities Council is keeping the UK at the forefront of international science and tackling some of the most significant challenges facing society such as meeting our future energy needs, monitoring and understanding climate change, and global security. The Council has a broad science portfolio and works with the academic and industrial communities to share its expertise in materials science, space and ground-based astronomy technologies, laser science, microelectronics, wafer scale manufacturing, particle and nuclear physics, alternative energy production, radio communications and radar.
STFC operates or hosts world class experimental facilities including in the UK the ISIS pulsed neutron source, the Central Laser Facility, and LOFAR, and is also the majority shareholder in Diamond Light Source Ltd.
STFC enables UK researchers to access leading international science facilities by funding membership of international bodies including European Laboratory for Particle Physics (CERN), the Institut Laue Langevin (ILL), European Synchrotron Radiation Facility (ESRF) and the European Southern Observatory (ESO). STFC is one of seven publicly-funded research councils. It is an independent, non-departmental public body of the Department for Business, Energy & Industrial Strategy (BEIS). www.stfc.ac.uk

For further information about the the University of Sheffield’s involvement in the T2K project, please contact Professor Lee Thompson via l.thompson@sheffield.ac.uk.