  A new air shower experiment of the Alborz Observatory, Alborz-I, located at
the Sharif University of Technology, Iran, will be constructed in near future.
An area of about 30$\times$40 m$^{2}$ will be covered by 20 plastic
scintillation detectors (each with an area of 50$\times$50 cm$^{2}$). A series
of experiments have been performed to optimize the height of light enclosures
of the detectors for this array and the results have been compared to an
extended code simulation of these detectors. Operational parameters of the
detector obtained by this code are cross checked by Geant4 simulation. There is
a good agreement between extended-code and Geant4 simulations. We also present
further discussions on the detector characteristics, which can be applicable
for all scintillation detectors with a similar configuration.
