The birth of Particle Astrophysics and Neutrino Astronomy

 Created on Wednesday 07 Jan 2009
by Άννα Χριστοδούλου

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An example of simulated data modeled for the CMS particle detector on the Large Hadron Collider (LHC) at CERNIn order to understand the mysteries of the Universe people have developed Astronomy, Astrophysics and Particle Physics, that uses high energy accelerators to investigate the conditions of the birth of the world. Astronomy was the first science the human developed. It was very practical, since it was used to split time into months, following the movements of the moon, to calculate the seasons of seeding, the summer period etc. The last 50 years astronomy welcomed more instruments apart from the traditional telescope, from satellite observatories to huge radio telescopes.

The photon, the light particle thanks to which we can see, is one of the many particles that exist in the world and until now it has been the exclusive messenger we had from the distant corners of the Universe. Particle Astrophysics has been born along with the idea of using also other particles to get more information about the world and the Universe. The neutrino particle, thanks to its rare properties, to react so weakly with matter, to travel almost at light speed and to “live” for a very long time, has been considered as the best alternative messenger we can get.

To observe the neutrinos we must be protected from the cosmic radiation that flows constantly to earth and prevents our special neutrino telescopes from detecting them. There are reports from the ancient years talking about philosophers who went down in wells and claimed to see the stars at daylight, because the depth of the well counterbalanced (“cut”) the sunlight. The process resembles with shading our eyes with our hand in order to distinguish something distant in the horizon. Therefore, in order to see neutrinos we must place our telescopes in a “shady” place such as under the sea, or inside deep mines under the mountains.

In the 70s researcher Ray Davis started to observe sun neutrinos in mines in Utah, in depth of approximately 1-2 km. His observations were contradictory to theory, as he could see only 30-40% of the predicted neutrinos. This problem was called the “neutrino problem” and has opened a new era in the Particle Astrophysics, introducing the Neutrino Astronomy and giving the first clues that neutrinos transform. There are three types of neutrinos, the electron neutrinos, the muon neutrinos and tau neutrinos and for the first time scientists suspected that these three different neutrinos could transform to one another, a phenomenon called “neutrino oscillation”.