Abstract
We present a study of the application of the Jagiellonian positron emission tomograph (J-PET) for the registration of gamma quanta from decays of ortho-positronium (o-Ps). The J-PET is the first positron emission tomography scanner based on organic scintillators in contrast to all current PET scanners based on inorganic crystals. Monte Carlo simulations show that the J-PET as an axially symmetric and high acceptance scanner can be used as a multi-purpose detector well suited to pursue research including e.g. tests of discrete symmetries in decays of ortho-positronium in addition to the medical imaging. The gamma quanta originating from o-Ps decay interact in the plastic scintillators predominantly via the Compton effect, making the direct measurement of their energy impossible. Nevertheless, it is shown in this paper that the J-PET scanner will enable studies of the text{ o-Ps }rightarrow 3gamma decays with angular and energy resolution equal to sigma (theta ) approx {0.4^{circ }} and sigma (E) approx 4.1,{mathrm{keV}}, respectively. An order of magnitude shorter decay time of signals from plastic scintillators with respect to the inorganic crystals results not only in better timing properties crucial for the reduction of physical and instrumental background, but also suppresses significantly the pile-ups, thus enabling compensation of the lower efficiency of the plastic scintillators by performing measurements with higher positron source activities.
Highlights
The positron emission tomography (PET) is based on registration of two gamma quanta originating from a positron annihilation in matter
We present a study of the application of the Jagiellonian positron emission tomograph (J-PET) for the registration of gamma quanta from decays of orthopositronium (o-Ps)
The J-PET is the first positron emission tomography scanner based on organic scintillators in contrast to all current PET scanners based on inorganic crystals
Summary
The positron emission tomography (PET) is based on registration of two gamma quanta originating from a positron annihilation in matter. Positronium, being a bound-state built from electron and anti-electron bound by the central potential, is an eigenstate of both charge (C) and spatial parity (P) operators, as well as of their combination (CP) It is well suited for the studies of these discrete symmetries in the leptonic sector. Since a detailed physics program of J-PET and its motivation is described elsewhere in a dedicated article [1], here as an example we would like only to discuss briefly experimental approach to determining the expectation value of the odd operator for the CPT symmetry, whose violation has not been observed so far As it was recently shown [18] the J-PET detector allows for a spin direction (S) determination of o-Ps created in cylindriθ.
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