Abstract
In recent years, much attention has been focused on neutrino research because it can shed new light on greatest mysteries in physics. A new experiment devoted to detection and investigation of reactor antineutrinos is being performed at the Institute of Experimental and Applied Physics, Czech Technical University in Prague using a highly segmented scintillating detector S3. This detector is polystyrene based and does not contain any dangerous or flammable materials and is absolutely safe to be placed in the close vicinity of the reactor. The most important feature of plastic scintillators for this experiment is the amount of photoelectrons per deposited energy, which defines the final energy resolution of the detector and a lot of effort has been put into improvement of detector element overall quality. The detector has been constructed as a result of these optimization experiments.