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14 december 2018

Approved FOM programme

Number 106.
Title The origin of cosmic rays (CRS)
Executive organisational unit FOM-Nikhef and BUW
Programme management Dr. A.J. Heijboer 
Duration 2008-2016
Cost estimate M€ 3.6

The primary objectives of the programme are: (i) the search for the sources of cosmic rays; (ii) the study of the primary composition of cosmic rays and (iii) measuring the energy spectrum of cosmic rays up to the highest possible values. Given the large range of energies involved two complementary probes will be used, i.e. neutrinos in the energy domain up to 1016 eV (and possibly beyond) and air showers induced by protons or heavy atomic nuclei for energies above 1018 eV.

Background, relevance and implementation
One of the key unresolved issues in astroparticle physics concerns the unknown origin of cosmic rays of very large energies. Cosmic rays are a collective name for a variety of subatomic particles that are continuously bombarding the outer layers of the Earth's atmosphere. While the Sun is a well-known source of low-energy cosmic rays, the origin of particles with energies in excess of 1012 eV has not yet been unambiguously identified. Supernovae explosions, for instance, are commonly believed to be the source of cosmic rays with energies up to 1015 eV, but so far it has not been possible to prove this observationally. Beyond this energy domain cosmic-ray particles must originate from unknown extra-galactic sources at very large distances. Some of these particles are reaching energies well in excess of the highest energies that can be produced in the most advanced man-made particle accelerators. In fact, cosmic rays are the only observed ultra-high energy (UHE) particles on Earth, i.e. with energies in excess of 1016 eV. Still, the acceleration mechanism(s) leading to such ultra-high energies and their sources remain largely unknown. 

The research will be carried out with the Antares deep-sea neutrino telescope, deployed in the Mediterranean Sea near Toulon at a depth of 2480 m , and the Pierre Auger air-shower Observatory (or Auger for short) in western Argentina near the city of Malargüe. Both Antares and Auger were completed in 2008 and are taking data continuously. As Antares and Auger are largely viewing the same part of the (southern) sky, these observatories do not only cover a complementary energy domain, but also allow for the observation of the same cosmic sources using different probes.
For the long term, Nikhef is actively involved in: the very large KM3NeT neutrino telescope project (FOM Programme 123) and the development of new detection technologies for existing (Auger) and a future cosmic-ray observatory (beyond Auger) using our expertise gained with the current detection systems deployed at Auger.
The scientific programme is carried out by five collaborating research groups. The research projects related to the Antares neutrino telescope are carried out by the groups in Amsterdam (FOM‑Nikhef and UvA/IHEF) and Groningen (KVI), while those related to Auger are carried out by RU/IMAPP, KVI and FOM-Nikhef. For each of the aforementioned research themes a number of specific projects has been defined that form the basis of the research work of a PhD student.

More information can be found at the origin of cosmic rays.

The final evaluation of this programme will consist of a self-evaluation initiated by the programme leader and is foreseen for 2016.

Please find a research highlight that was achieved in 2013 within this FOM programme here.