Fig. 11.

Left dependency of attenuation coefficient on incident gamma quanta energy. Data taken from [34]. Right distribution of energy deposited by gamma quanta in plastic scintillators originating from $\text{o-Ps}\to 3\mathit{\gamma }$ annihilations. The shown spectrum is a convolution of the energy distribution of gamma quanta from the $\text{o-Ps}\to 3\mathit{\gamma }$ decay (Fig. 7) and the Klein–Nishina distribution of kinetic energy of electrons acquired via Compton scattering [35]. Spectrum includes the absorption dependence on the energy (left panel) and the detector energy resolution