PALS investigations of free volumes thermal expansion of J-PET plastic scintillator synthesized in polystyrene matrix

Abstract

Abstract. The polystyrene doped with 2,5-diphenyloxazole as a primary fl uor and 2-(4-styrylphenyl)benzoxazole as a wavelength shifter prepared as a plastic scintillator was investigated using positronium probe in wide range of temperatures from 123 to 423 K. Three structural transitions at 260, 283, and 370 K were found in the material. In the o-Ps intensity dependence on temperature, the signifi cant hysteresis is observed. Heated to 370 K, the material exhibits the o-Ps intensity variations in time.

Positronium Formation in Organic Liquids

“…Tiny (few ps, imposed on 220 ps) differences of positron lifetimes in Czochralski-grown silicon allowed to detect clustering of oxygen atoms around defects [4,5]. In polymers, monitoring o-Ps lifetime (with similar values to those in liquids) became a powerful tool to study phase transitions [6] and dynamics of peristaltic vibrations of the chains [7]. A new generation of positron emission tomography (J-PET) [8] triggered again the interest in positron annihilation in organic molecules, and in particular in presence of oxygen, but expected differences between specific human tissues are tiny.…”

Potential of the J-PET Detector for Studies of Discrete Symmetries in Decays of Positronium Atom --- A Purely Leptonic System

“…The Jagiellonian Positron Emission Tomograph (J-PET) was constructed as a prototype of a cost-effective scanner for the simultaneous metabolic imaging of the whole human body [43,63,72]. It is optimized for the detection of photons from the electron-positron annihilation with high time-and angular-resolutions, thus providing new opportunities for research with photons originating from the decays of positronium atoms in fundamental physics, as well as in life and material sciences [99,[101][102][103].…”

Calculation of the time resolution of the J-PET tomograph using kernel density estimation

“…In this study, the parameters of the distribution were selected in order to describe the properties of light signals observed in the BC-420 plastic scintillator. However, our group develops a novel type of plastic scintillator and examines the influence of the chemical composition of the plastic scintillator on the overall performance of the J-PET detector (Wieczorek et al 2015a(Wieczorek et al , 2015b(Wieczorek et al , 2016. Application of the proposed model to that task, enables us to use information about the shape of the distribution of the time of photon emission directly to predict the CRT of the J-PET detector.…”