ICARUS INAUGURATION
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.
The experiment was
realized in close collaboration with
national industries. The
extremely
refined mechanics of the detector (about 54,000
steel wires strung on huge frames of dimensions of
approximately 4 x 18 m2)
was realized by the
Cinel Strumenti Scientifici. The electronics was
engineered and
constructed in collaboration
with the
CAEN Spa. The
cryostat and cryogenic
systems were realized in cooperation with Air Liquide Italia and
Stirling (a
Dutch company).
