Press Release

A Step Closer to Solving one of the Biggest Mysteries in Fundamental Physics?

By SpaceRef Editor
June 15, 2011
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A Step Closer to Solving one of the Biggest Mysteries in Fundamental Physics?
A Step Closer to Solving one of the Biggest Mysteries in Fundamental Physics?

Where did all the matter in the universe come from? This is one of the biggest mysteries in fundamental physics, and exciting results released on 15 June 2011 from the international T2K neutrino experiment in Japan could be an important step towards resolving this puzzle.

The intriguing results indicate a new property of the enigmatic particles known as neutrinos.

There are three types of neutrinos (called flavors) — one paired by particle interactions with the familiar electron (called the electron neutrino), and two more paired with the electron’s heavier cousins, the mu and tau leptons. Previous experiments around the world have shown that these different flavors of neutrinos can spontaneously change into each other, a phenomenon called “neutrino oscillation”.

Two types of oscillations have already been observed, but in its first full period of operation the T2K experiment has already seen evidence for a new type of oscillation (the appearance of electron neutrinos in a muon neutrino beam). This means that we have now observed that neutrinos can oscillate in every way possible.

This level of complexity opens the possibility that the oscillations of neutrinos and their anti-particles (called anti-neutrinos) could be different. And if the oscillations of neutrinos and anti-neutrinos are different, it would be an example of what physicists call CP violation. This could be the key to explaining why there is more matter than anti-matter in the universe (an excess which could not happen within the known laws of physics).

The experiment ran from January 2010 until 11 March this year, when it was dramatically interrupted by the Japanese earthquake. Fortunately, the multinational T2K team were unharmed, and their highly sensitive detectors were largely undamaged. Six clean electron neutrino events are observed in the data from before the earthquake, while in the absence of oscillations there should only have been 1.5. Even though such an excess could only happen by chance about one time in a hundred, that is not good enough to confirm a new physics discovery, so this is called an “indication”.

Prof. Dave Wark of STFC and Imperial College London, who served for four years as the International co-spokesperson of the experiment and is head of the UK group, explains, “People sometimes think that scientific discoveries are like light switches that click from ‘off’ to ‘on’, but in reality it goes from ‘maybe’ to ‘probably’ to ‘almost certainly’ as you get more data. Right now we are somewhere between ‘probably’ and ‘almost certainly'”.

Prof. Christos Touramanis from Liverpool University is the Project Manager for the UK contributions to T2K: “We have examined the near detectors and turned some of them back on, and everything that we have tried works pretty well. So far it looks like our earthquake engineering was good enough, but we never wanted to see it tested so thoroughly”.

Prof. Takashi Kobayashi of the KEK Laboratory in Japan and spokesperson for the T2K experiment, said “It shows the power of our experimental design that with only 2% of our design data we are already the most sensitive experiment in the world for looking for this new type of oscillation”.

STFC is the UK sponsor of particle physics and supports the UK universities involved in the T2K experiment.

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Contact: Stephanie Hills STFC Media Manager +44 (0)1235 445398 stephanie.hills@stfc.ac.uk

About T2K

The experiment is a huge undertaking with over 500 scientists from 12 countries. The UK has invested £14.3M in the T2K project. There are three elements to the experiment:

1. A beam of muon neutrinos is produced at the Japan Proton Accelerator Research Center in Tokai, Japan. STFC engineers from the Rutherford Appleton Laboratory helped in the design, production, and testing of a number of the elements of this neutrino production system.

2. The neutrinos then pass through a complex set of near detectors located 280 meters from the target in order to determine the neutrino beam’s composition and properties before the neutrinos have a chance to oscillate. 8 STFC-supported institutions (listed below) were involved in the production of a variety of components for these near detectors.

3. The neutrinos then fly under the ground for 295 km across Japan to the mammoth Super-Kamiokande neutrino detector (a tank of 50,000 tons of ultra-pure water surrounded by sensitive optical detectors which can see the very faint flashes of light emitted by the very rare interactions of passing neutrinos with the water). This is capable of telling muon neutrinos from electron neutrinos with high precision, and is thus ideal for looking for the appearance of a small fraction of electron neutrinos appearing in the muon neutrino beam, the key signature of this new type of oscillation.

T2K UK collaboration and contacts: * STFC Daresbury Laboratory — Prof. Dave Wark * STFC Rutherford Appleton Laboratory — Prof. Dave Wark * Imperial College London — Prof. Dave Wark * Lancaster University — Prof. Peter Ratoff * Liverpool University — Prof. Christos Touramanis * Queen Mary University London — Dr. Francesca Di Lodovico * Sheffield University — Dr. Lee Thompson * University of Oxford — Dr. Giles Barr * Warwick University — Dr. Gary Barker

About 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; ISIS pulsed neutron source, the Central Laser Facility, and LOFAR. STFC is also the majority shareholder in Diamond Light Source Ltd. * overseas; telescopes on La Palma and Hawaii

It 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, Innovation and Skills (BIS).

SpaceRef staff editor.