  In the presented paper curves of constant $\epsilon_{T} / n_{charged}$ are
calculated in $T-\mu_{B}$ plane, in the framework of a single-freeze-out
thermal hadron gas model. The ratio is a theoretical equivalent of ${{dE_{T}}
\over {d\eta}}_{\mid \eta=0} / {{dN_{ch}} \over {d\eta}}_{\mid \eta=0}$
measured at RHIC and SPS. In both $\epsilon_{T}$ and $n_{charged}$ decays of
hadron resonances are taken into account. The freeze-out temperature
$T_{f.o.}=156_{-11}^{+14}$ MeV is obtained for RHIC, whereas $T_{f.o.}=134-140$
MeV is evaluated for SPS.
