An advanced new facility that specializes in catching elusive cosmic rays was initiated within the framework of a joint Russian-German-Italian project. A Tunca-Hi-SCORE observatory will be built near Lake Baikal in Tunka valley (Russia). The project aims to study gamma ray components of high-energy space radiation, thus revealing the secrets of the most energetic events in the Universe.

Tunka-HiSCORE is a joint project to study high energy space radiation emitted from distant sources in space, namely - gamma rays, and nuclei, which make up so-called cosmic rays, the high-energy radiation coming from space, which was first attributed to space sources by Victor Hess 100 years ago.

The majority of cosmic rays are high energy charged particles, positive protons primarily, but also gamma rays and heavier nuclei. They are significantly different: while charged nuclei are strongly deflected by the magnetic field lines, gamma rays are neutral and therefore propagate directly after being emitted.

The name 'Tunka' comes from the name of valley near Lake Baikal, where earlier in 2009 the Tunka-133 facility, which studies ultra high energy cosmic rays (UHECR), was deployed. This one consists of 133 optical detectors used to catch so-called Cherenkov radiation, which is emitted in the atmosphere of the Earth, when it is hit by a charged particle of cosmic rays.

Rather fortunately for human beings (since space radiation can be extremely harmful), cosmic rays cannot penetrate the atmosphere. However, they interact with atmospheric particles and give rise to secondary particles, which in turn interact with the atmosphere and eventually result in so-called extensive atmospheric showers (EAS) of particles accompanied by flashes of light, which is called Cherenkov's radiation. This light can be observed with the help of optical telescopes.

An array of such Cherenkov telescopes was deployed in the Tunka valley (participants are four Russian scientific organizations, Italian Turino University and German DESY) and its results showed the high efficiency of the telescopes, so much so that the Russian Academy of Sciences has decided to extend the facility, involving hiSCORE project.

HiSCORE (Hundred Square-km Cosmic ORigin Explorer) is originally a foreign project aimed at specific studies of very high energy gamma rays above 10 tera electron volts and cosmic rays from 100 TeV up to 1 EeV. The scientists want to find a clue to which mechanisms accelerate particles to such energies, far beyond what can be achieved at the Large Hadron Collider.

The project stipulates, that a number of specially developed detector will be spread on the site of about 100 square km. Tunka valley was chosen because of the already existing infrastructure, and since last Spring prototype station has been working there. Now, it was announced that major works were commenced on the site. The overall lifetime of the project is 10 years.

It is planned that in 2013-14 the area of the facility will be around one square kilometer, and by 2016 - more than 10 square kilometers, in other words, the greater the area, the better the data. HiSCORE also hopes to collaborate with the Pierre Auger observatory in Argentina.

The price of the project is named as no less than 1.5 billion rubles. It is supported by the Russian Foundation for Basic Research and the Helmholtz Society (Germany).

The participants are: the Institute for Nuclear Research of the Russian Academy of Sciences, Skobeltsyn Institute for Nuclear Physics (Lomonosov Moscow State University), Applied Physics Institute (Irkutsk State University), from Russia, and the University of Hamburg, Karlsruhe Technology Institute, and DESY from Germany.