A neutrino Detector can solve the mysteries of physics – Now action is required!

ESS can provide the answer to some of the unsolved mysteries of physics – with an underground neutrino detector in a mine 500 km from Lund in southern Sweden. If we are to succeed, support is required from both Swedish industry and Swedish politicians, write Tord Ekelöf and Colin Carlile.

Just outside Lund, the world’s most powerful proton accelerator, The European Spallation Source, ESS, is being built. It will be used to generate a uniquely high flux of neutrons that will enable world-leading studies of the atomic structure of many different types of materials, such as biological tissue and magnetic materials.

We are leading an international project that is about upgrading the ESS accelerator so that it can also be used for world-leading research in fundamental physics. By generating neutrinos and muons, in addition to neutrons, the ESS could provide the answer to a riddle that has so far eluded scientists all over the world. The project is called the ESS Neutrino Super Beam.

Current scientific investigations indicate that the Big Bang released enormous amounts of energy that resulted in the creation of equal parts of matter and antimatter. According to the so-called symmetry laws of physics, the two types of matter should, only a moment later, have completely obliterated each other. But quite obviously matter slightly dominated antimatter, and this excess of matter led to the universe – and eventually human life. The question is – how could this happen?

Important research findings have resulted in the Big Bang theory and the Standard Model for particle physics. Using these two theories, many of the properties of the universe can be described and explained – its age, structure, evolution and accelerating expansion. The discovery of the Higgs particle provided some additional support for the Standard Model, but several other observations hint at its shortcomings and contradictions.

What we physicists call CP symmetry – that the properties of a particle are unchanged if you both change the sign of its charge (C) and transform it into its mirror image (P) – requires that a particle behaves identically to its antiparticle.

When a particle collides with its antiparticle, they are both obliterated with the release of energy in the form of light. This process is used in the PET cameras in our hospitals – electrons and positrons destroy each other and are converted into high-energy X-ray light with which images of internal body organs can be created.

For every particle created from energy released in the Big Bang, an antiparticle must also have been created. To explain the phenomenon that, shortly after the Big Bang, there were more particles than antiparticles, the principle of CP symmetry must have been broken.

Researchers have, without success, looked for a clear violation of CP symmetry in many elementary particles – but not neutrinos! The reason for this is that neutrinos interact extremely weakly with matter and are very difficult to detect. It is therefore necessary to have an extremely intense flux of neutrinos and a very large detector to be able to measure their properties.

This is where ESS comes into the picture. Nowhere else in the world will such a high flux of neutrinos, in addition to the neutrons, be able to be produced. Although there are facilities in Japan and the USA today, an even more powerful facility is needed in the future to clearly detect and measure the violation of CP symmetry.

Our proposal envisages a uniquely intense neutrino beam that will be aimed at a very large underground neutrino detector approximately 500 km from Lund. Suitable locations for the detector have been identified in Garpenberg and the Zinkgruvan in central Sweden.

A consortium of researchers from eleven European countries has studied how the ESS accelerator can be enhanced and the underground neutrino detector designed. New cutting-edge technology will certainly be needed and for this the participation of Swedish high-tech industry is necessary.

Experience shows that major technical challenges of this type invariably lead to new innovations and applications in fields as diverse as IT, healthcare, energy technology and environmental protection – areas that are important for the continued development of our society and our culture. If we are to succeed in this initiative, strong support is required, not only from the research community but also from industry, Swedish politicians and the general public, but with the breakthroughs that are within reach, the mobilisation of such support should not be impossible