Polarization of the Three-Photon Annihilation Radiation

E. Bleuler, H. Bradt

N. Yongram, Edward B. Manoukian

Alexander O. Strizhak, J. N. Abdurashitov, А. Г. Баранов +2 more

Abstract The experimental setup for study of Compton scattering of entangled and decoherent annihilation gammas is described. These gammas are born in two-photon positron-electron annihilation. Polarizations of annihilation gammas are mutually orthogonal, while the polarization of each photon is indefinite. If one of the photons of the pair interacts with matter, the pair becomes decoherent and photons acquire the determined polarization states. The kinematics of Compton scattering depends on the polarization states and can be different for entangled and decoherent pairs of annihilation photons. The angular correlations of scattered gammas for both, entangled and decoherent states are measured and compared. It is shown, that the kinematics of Compton scattering are similar for both cases.

Vanik E. Mkrtchian, V. O. Chaltykyan

Paweł Moskal, Deepak Kumar, Sushil K. Sharma +25 more

In state-of-the-art positron emission tomography (PET), information about annihilation photon polarization is unavailable. Here, we present a PET scanner built from plastic scintillators, where annihilation photons primarily interact via the Compton effect, providing information about both photon polarization and propagation direction. Using this plastic-based PET, we determined the distribution of the relative angle between polarization planes of photons from positron-electron annihilation in a porous polymer. The amplitude of the observed distribution is smaller than predicted for maximally quantum entangled two-photon states but larger than expected for separable photons. This result can be well explained by assuming that photons from pick-off annihilation are not entangled, while photons from direct and parapositronium annihilations are maximally entangled. Our result indicates that the degree of entanglement depends on the annihilation mechanism in matter, opening avenues for exploring polarization correlations in PET as a diagnostic indicator.

Guido Bertolini, E. Diana, Alexandria Scotti