  We use the non-statistical fluctuation instead of the full one to explore the
higher moment singularities of net proton event distributions in the
relativistic Au+Au collisions at $\sqrt{s_{NN}}$ from 11.5 to 200 GeV
calculated by the parton and hadron cascade model PACIAE. The PACIAE results of
mean ($M$), variance ($\sigma^2$), skewness ($S$), and kurtosis ($\kappa$) are
consistent with the corresponding STAR data. Non-statistical moments are
calculated as the difference between the moments derived from real events and
the ones from mixed events, which are constructed by combining particles
randomly selected from different real events. An evidence of singularity at
$\sqrt{s_{NN}}\sim$ 60 GeV is first seen in the energy dependent
non-statistical $S$ and $S\sigma$.
