  The emission of neutrons from heavy ion reactions is an important observable
for studying the asymmetric nuclear equation of state and the reaction
dynamics. A 20-unit neutron array has been developed and mounted on the compact
spectrometer for heavy ion experiments (CSHINE) to measure the neutron spectra,
neutron-neutron and neutron-proton correlation functions. Each unit consists of
a $\rm 15\times 15\times 15~cm^3$ plastic scintillator coupled to a $ \phi=52
~\rm mm$ photomultiplier. The Geant4 simulation with optical process is
performed to investigate the time resolution and the neutron detection
efficiency. The inherent time resolution of 212 ps is obtained by cosmic ray
coincidence test. The n-$\gamma$ discrimination and time-of-flight performance
are given by $\rm ^{252}Cf$ radioactive source test and beam test. The neutron
energy spectra have been obtained in the angle range $30^\circ \le \theta_{\rm
lab} \le 51^\circ$ in the beam experiment of $^{124}$Sn+$^{124}$Sn at 25 MeV/u
with CSHINE.
