March 29 ICARUS (Imaging Cosmic and Rare Underground Signals) was inaugurated at the Gran Sasso National Laboratory of the INFN (National Institute for Nuclear Physics)
ICARUS, a project headed by Nobel Laureate Carlo Rubbia, started operation on May 27, 2010. It boasts a technology unique in the world and was built in close collaboration with Italian companies.
March 29, the ICARUS experiment was officially inaugurated in the Gran Sasso National Laboratory. The experiment is located in Hall B of the underground laboratories.
ICARUS started working gradually from May 27th of last year and it registered data since the very beginning, capturing the tracks left by rare cosmic rays able to reach the depths of the laboratory and, above all, the interaction events of neutrinos from the beam sent from CERN, that crosses the earth’s crust for more than 700 kilometers before intercepting the experiment detectors under the Abruzzo mountain. The experiment will study the neutrino oscillation phenomenon, detecting the artificial neutrinos that reach the Gran Sasso Laboratory from CERN, along with the OPERA experiment.
Besides the neutrinos coming from CERN, the experiment will also study atmospheric neutrinos and those produced by the Sun, as well as extraordinary events occurring in the cosmos such as Supernovae explosions and the collapse of neutron stars. ICARUS also has another ambitious objective: the observation of the decay of nucleons (protons and neutrons), a phenomenon never observed before, though it is searched for by physicists worldwide.
ICARUS is the largest liquid argon detector in the world that allows to obtain (reconstruct) high resolution images of interaction events in real time, measuring the physical characteristics of the particles produced in the events. Twenty years of research and development were needed to construct it and put it into operation. INFN is the world leader in this unique technology, which will permit the opening of new horizons towards the understanding of the Universe. The installation, functioning and continuous control of the underground apparatus prove the high level of technology in the technical and security infrastructures of the Gran Sasso Laboratory.
The ICARUS Collaboration is constituted by physicists from several sections of INFN and Italian university departments (L’Aquila, LNGS, Milan, Naples, Padua, Pavia) as well as groups of physicists from Poland, USA and Russia.
Carlo Rubbia, spokesperson and “father” of the experiment emphasizes that ICARUS is able to study, in an innovative and original way, the neutrino interactions, those extraordinary particles which play a fundamental role for the understanding of the Universe. Today we realize that neutrinos are not just a simple copy of elementary particles : they have unique characteristics, specific to themselves. In particular, neutrinos could be the main cause of the existence of dark matter, one of the greatest discoveries in the last years. Dark matter indicates to us that what we are made of, the hadronic matter generated during the cosmogenesis, is not the main form of matter in the Universe. 95% of the universe has yet to be discovered!
Roberto Petronzio, President of the Istituto Nazionale di Fisica Nucleare (National Institute for Nuclear Physics) emphasizes that Science works more and more through tools that reconstruct the data, but nothing at the end, can replace the direct observation of events, when this is possible. ICARUS is a detector which takes pictures of neutrinos with a very high level of electronic visualisation. In some ways, it is an ultramodern version of the first bubble chambers, the ones that were used to study cosmic rays.
According to Lucia Votano, LNGS Director, ICARUS is an innovative apparatus capable of reconstructing in 3D any particle interactions in its interior. The operation of such a large and complex apparatus in an underground laboratory constitutes a decisive step forward to the realization of future experiments with a liquid argon volume of many thousands tons and furthermore it is a proof of the high level of technology used in the Gran Sasso Laboratory.
How it works?
ICARUS uses liquid argon to detect the tracks of ionizing particles produced by cosmic rays and by neutrinos. This technology conceptually represents the evolution of the famous bubble chamber, an instrument consisting of a volume filled with liquid hydrogen or deuterium, in which the passage of particles was detected by photographing the micro bubbles generated by ionization. The bubbles permitted to reconstruct in great detail the tracks of ionizing particles. ICARUS is a wire detector immersed in 600 tons of liquid argon which allows the electronic registration of the passage of particles, by reading the electric charges released along the track by ionization processes, with a velocity much higher than that of the bubble chamber, while keeping the same spatial and energy resolution. This detector can be considered the forerunner of a new series of ever more evolved devices for observing the Universe and study its fundamental components.