The ALICE Detector at the LHC
Apart from the two high luminosity experiments ATLAS and CMS as well as the LHCb detector for the study of beauty
physics, the LHC has one experiment dedicated to Pb-Pb ion operation which is
called
The running of the coupling constant in Quantum Chromodynamics (QCD), which is the quantum field theory describing the strong interaction, gives rise to the
colour confinement at small momentum transfer. The quarks and gluons, which are the constituents of the matter surrounding us, are therefore
only observed as confined states, the hadrons.
In heavy-ion collisions, where high temperatures and high densities of matter are reached, hadrons begin
to interpenetrate each other and a new state of matter is expected to be formed, in which quarks and gluons can be considered free.
This state is called quark-gluon plasma (QGP).
The existence and the description of this phase of matter is a central issue in the understanding of QCD.
Just shortly after the big bang, before hadrons were formed out of quarks and gluons, the universe was in such a state of
extremely high temperature and energy density.
Since the phase transition from confinement to deconfinement at high temperatures is expected to be reached in heavy-ion collisions
it is possible to probe the QGP by measuring the particles evolving from the collisions between heavy ions.
With the ALICE detector it is therefore possible to study the properties and the evolution of the QGP and to observe how it gives rise
to the production of the particles that are the constituents of the matter in our universe today.
