  Momentum correlation functions between $\pi$, $K$ and $p$ are calculated for
several heavy-ion collision systems, namely
$_{5}^{10}\textrm{B}+_{5}^{10}\textrm{B}$,
$_{8}^{16}\textrm{O}+_{8}^{16}\textrm{O}$,
$_{20}^{40}\textrm{Ca}+_{20}^{40}\textrm{Ca}$ and
$_{79}^{197}\textrm{Au}+_{79}^{197}\textrm{Au}$ in central collisions as well
as $_{79}^{197}\textrm{Au}+_{79}^{197}\textrm{Au}$ collision in different
centralities at center of mass energy $\sqrt{s_{NN}}$ = 39 GeV within the
framework of A Multi-Phase Transport (AMPT) model complemented by the
Lednick$\acute{y}$ and Lyuboshitz analytical method. The results present the
centrality and system-size dependence of the momentum correlation functions
among pairs of $\pi$, $K$ and $p$, from which the emission source-size can be
deduced. It is found that the deduced source sizes increase with the decreasing
of centrality for Au + Au system or with the increasing of system-size in
central collisions with different nuclear size. In addition, through the
momentum correlation functions of nonidentical particle pairs gated on
velocity, the average emission sequence of non-identical particles can be
indicated. The results illustrate that in the small relative momentum region,
protons are emitted in average earlier than $\pi^+$ and $K^+$, and $K^+$ are
emitted averagely earlier than $\pi^+$. Furthermore, it seems that larger
interval of the average emission order among them is exhibited for smaller
collision systems. The present study sheds light on the dynamics of light
particle emission at RHIC energy.
