Skobeltsyn Institute of Nuclear Physics
Lomonosov Moscow State University

Experimental detection of the critical vicinity of the phase transition of dense hadronic matter into
quark-gluon matter is one of the main goals of the relativistic heavy-ion collisions physics. A novel
method for searching such a vicinity is proposed. Its essence is in selection of ultracentral collision
events, based on the azimuthal isotropy of the distribution of the particles produced in an event and
in search for the behaviour regime change of, for instance, two-dimensional dependence of a certain
observable on the collision energy and mass of one of the colliding nuclei. Location and size of the
critical vicinity can be estimated using an appropriate parametrization, while identification of the
phase transition will stem from the physical contents of the models, most adequately reproducing the
observed dependence, including the regime change. The advantage of the centrality criterion, based
on the azimuthal isotropy, — its independence, to a large extent, of the collision energy and of the
masses of the colliding nuclei, as well as of physics of the models, used for the method calibration, in
contrast to criteria, based on multiplicity.