  Local density fluctuations near the QCD critical point has been suggested to
exhibit a power-law behavior which can be probed by an intermittency analysis
on scaled factorial moment (SFM) in relativistic heavy-ion collisions. The
collision energy and centrality dependence of the second-order SFMs are
systematically investigated in Au $+$ Au collisions at $\sqrt{s_{NN}}$ = 7.7,
11.5, 19.6, 27, 39, 62.4, and 200 GeV within the UrQMD model. We estimate the
noncritical background in the measurement of intermittency and propose a
cumulative variable method to effectively remove the background contributions.
We further study the effect of particle detection efficiency by implementing
the RHIC (STAR) experimental tracking efficiencies in the UrQMD events. A
cell-by-cell method is proposed for experimental application of efficiency
corrections on SFM. This work can provide a guidance of background subtraction
and efficiency correction for the experimental measurement of intermittency in
the search of the QCD critical point in heavy-ion collisions.
