A wide range of scintillation materials are used in various fields of medicine and security and for scientific purposes in research institutions. Examples of such purposes are medical imaging, ionizing radiation detection, and spectroscopy. Scintillators can be composed of organic or inorganic materials in combination with solvents. Gaseous materials can also be used for scintillation counting; the most common example is helium 3 (3He) counters used for neutron detection.
Scintillation materials are typically liquid, plastic, or crystal. Plastic scintillators are more durable than liquid scintillators and can be machined into nearly any shape. They have many advantages such as fast rise and decay times, high optical transmission, ease of manufacturing, low cost, and large available size. Because of these characteristics, there has been an increased interest in developing plastic scintillators and an interest in their many applications in nuclear physics and radiation detection, and particle identification.
The most common preparation method for plastic scintillators is thermal polymerization of a solution containing a liquid monomer. The polymerization techniques vary with the composition and size of the desired sample. The polymerization is initiated slowly at a low temperature and then completed at a high temperature. In this study, three plastic scintillators 4.5 cm in diameter and 2.5 cm in length were fabricated by the polymerization of the styrene monomer 2.5-diphenyloxazole (PPO) and 1,4-bis benzene (POPOP).
Gamma ray spectra were measured using standard gamma ray sources such as cesium 137 (137Cs), sodium 22 (22Na), and cobalt 60 (60Co). Energy was calibrated by analyzing the pulse spectra. The purpose of the energy calibration was to convert the channels in the pulse spectra into gamma ray energy. Relative light output was estimated to compare the fabricated scintillators with a commercial scintillator (BC-408 scintillator; Saint-Gobain, Paris, France).