Nikhef researchers study neutrinos, which are neutral subatomic particles that pass straight through the Earth. They did so as part of a collaboration with ANTARES (a neutrino telescope on the bottom of the Mediterranean Sea) in France and now in a new international project called KM3NeT.

What is KM3NeT?

KM3NeT stands for ‘Cubic Kilometre Neutrino Telescope’. It is a neutrino telescope currently being built as a successor to ANTARES.

Neutrinos are uncharged subatomic particles. They have almost no mass. They also interact very weakly with matter and are therefore extremely difficult to detect. If neutrinos originating from the universe hit a mass of water on Earth, for example, most will shoot right through it. Only very occasionally will they collide with water molecules. This creates electrically charged muons that move in almost the same direction as the neutrinos. These muons produce light as they move through the seawater. We call this Cherenkov radiation.

ANTARES was a neutrino telescope located 40 km off the coast near Toulon, France, at a depth of 2,500 metres on the seabed. To improve sensitivity to neutrino sources, a much larger neutrino telescope than ANTARES was needed. To this end, construction of KM3NeT, a neutrino telescope more than a cubic kilometre in size, began several years ago. The detector’s location on the seabed was chosen so that it is largely shielded from interfering particles coming from the atmosphere. The aim of KM3NeT is to study neutrinos originating from the cosmos.

The building blocks of KM3NeT are so-called Digital Optical Modules (DOMs). These are glass spheres filled with 31 phototubes used to measure Cherenkov radiation. KM3NeT consists of lines about 180 metres long (France) and about 800 metres long (Italy). Attached to one line are 18 DOMs. KM3NeT currently consists of 46 lines; 28 in Italy and 18 in France. The final goal is 115 lines in France and 2x 115 lines in Italy.

A Digital Optical Module (DOM)
What does KM3NeT study?

KM3NeT is currently under construction to detect the fingerprints of neutrinos that originate from far-away astrophysical objects. Detecting and studying neutrinos is important to learn more about their behaviour. However, they can also be used to study the properties of their sources.

Researchers hope to use KM3NeT to discover where cosmic radiation comes from and how particle accelerators in the Universe work.

What is the role of Nikhef?

The DOM, the main component of the KM3NeT neutrino telescope, was largely designed by Nikhef, from concept to implementation. Nikhef also contributes much of the electronics, optical network, software and analysis of measurement data. The first two operational lines were assembled at Nikhef. The construction of the remaining DOMs is no longer done only at Nikhef; other production lines have already been set up in Europe that run with it. Almost half of the 1,230 DOMs built so far have been built at Nikhef and more than 30 lines have already been assembled at Nikhef.

More information

Fundamental research

This research programme is a prime example of fundamental scientific research, aimed at gathering basic knowledge about everything around us. At the heart of this type of research is curiosity about what our Universe is made of and how it came to be. There’s much that we know already, for example that all visible matter is built up from atoms, yet many questions remain unanswered.

Fundamental research is not aimed at realizing applications in the short term. Still, one thing is for sure: no one can predict which ground-breaking applications will eventually emerge from this research. History shows that today’s fundamental knowledge forms the breeding ground for tomorrow’s discoveries.

Steeds meer KM3NeT in de diepzee: article in Nikhef magazine DIMENSIES (Dutch only)
Interview with KM3NeT researcher Rasa Muller in Nikhef magazine DIMENSIES (Dutch only)
KM3NeT (Dutch only, article in the New Scientist special about Nikhef)

The website of KM3NeT

The below video shows a tour through the Nikhef lab where the KM3NeT-DOMs are made: