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Humboldt-Universität zu Berlin - Faculty of Mathematics and Natural Sciences - Experimental Particle Physics

Neutrino Telescopes

Sketch of the IceCube detectorNeutrinos are electrically neutral elementary particles of which there exists three different types (electron, muon and tau neutrinos).  From neutrino oscillation experiments in which these three neutrino types convert into each other it is known that their mass must be very tiny but finite.  Neutrinos are only subject to the weak force/interaction and so, they interact only rarely with matter and by this, are hardly detectable. 

The technique to detect neutrinos varies according to the energy of the neutrinos which in turn depends on the neutrinos' origin (the Sun, particle showers of cosmic radiation in the atmosphere or extraterrestric neutrinos) as well as on their production mechanism.  The flux of highly energetic, extraterrestric neutrinos is quite low and therefore, detectors with a huge volume are needed, which only can be realized in natural materials (water or ice).

Humboldt University Berlin participates in IceCube, a neutrino telescope experiment at the geografic Southpole.  IceCube uses the polar ice as a detector medium in which the neutrinos, due to the weak force, produce electrons, muons or tauons whose Cherenkov light (see blue area in the picture) is detected by photosensitive sensors (grey spheres in the picture).  The sensors of IceCube cover a volume of one cubic kilometre.  On the basis of the different runtimes of the Cherenkov light to the sensors the direction of the particle (i. e. from above or below, across the Earth) can be inferred.  By crossing the Earth a lot of background processes are eliminated.  So, IceCube observes the northern hemisphere through the Earth.

 


Detectors | Cherenkov Telescopes | Collider Experiments | Neutrino Telescopes