  Indian Scintillator Matrix for Reactor Anti-Neutrinos (ISMRAN), a plastic
scintillator array (10$\times$10), is being constructed for the purpose of
electron anti-neutrino ($\overline\nuup_{e}$) detection for reactor monitoring
applications. A prototype detector called mini-ISMRAN, which consists of 16$\%$
of ISMRAN, has been setup for studying the detector response, background rates
and event characterization in the reactor and non-reactor environment. The data
acquisition system based on waveform digitizers is being used for pulse
processing and event triggering. Monte-Carlo based simulations using GEANT4 are
performed to optimize lead (Pb) and borated polyethylene (BP) shielding for
background reduction and to study the positron, neutron and $\gamma$-ray
response in the ISMRAN detector. Characterization of plastic scintillator
detectors with known radioactive sources is done for energy, timing and
position measurements. Using the energy summation and bar multiplicity
selection, coincident events from $\mathrm{{}^{60}Co}$ decay are reconstructed
in non-reactor environment. Results from background measurements using various
detectors are quantified in reactor ON and OFF condition. The shielding of 10
cm Pb and 10 cm BP along with the requirement of hits in multiple bars, reduces
the uncorrelated background in reactor ON condition.
