The Distribution of Compton Scattered Annihilation Photons, and the Einstein-Podolsky Argument.

L. R. Kasday, Jack D. Ullman, C. S. Wu

Mendel Sachs

Michael L. G. Redhead

J. N. Abdurashitov, А. Г. Баранов, D. S. Borisenko +8 more

Abstract An experimental setup for studying the Compton scattering of annihilation photons in various (entangled and decoherent) quantum states is presented. Two entangled γ-quanta with an energy of 511 keV and mutually orthogonal polarizations are produced by positron-electron annihilation in a thin aluminum plate and are emitted in opposite directions. To measure both photons, the setup provides two equivalent arms of Compton polarimeters. A Compton polarimeter consists of a plastic scintillation scatterer and an array of NaI(Tl) detectors for measuring photons deflected at an angle of 90°. The intermediate scatterer of the GAGG scintillator with SiPM readout is inserted into one of the arms to create a tagged decoherence process prior to the measurement of annihilation photons in polarimeters. The performance of Compton scatterers and NaI(Tl) counters is discussed. The polarization modulation factor and the analyzing power of Compton polarimeters are evaluated from the angular distributions of scattered gammas. The Compton scattering of photons in entangled and decoherent states is compared reliably for the first time.

V. N. Aleshechkin

Sultan Musin, A. Ivashkin, Alexander O. Strizhak

Abstract This work presents the GEANT4 simulation of the experimental setup for studying the Compton scattering of annihilation photons and compares the simulation results with the experimental data. Two 511 keV photons are born in electron-positron annihilation at rest and have mutually orthogonal polarization which is measured by the system of Compton polarimeters. Each polarimeter consists of scatterer of initial annihilation photons and NaI(Tl) detectors of scattered at 90° photons. Additionally, an intermediate scatterer of GAGG scintillator is used to produce the tagged decoherent photons. Different cases of two-photon quantum states have been simulated. In the first case, the setup response to Compton scattering of entangled photons with mutually perpendicular polarization was studied. In the second case similar study was done for decoherent photons that are produced if one of the initial photons interacts in intermediate scatterer. Distinctions in Compton scattering for these two cases have been obtained and compared to the experimental results. Energy spectra in NaI(Tl) detectors and angular distributions of scattered photons are presented for both entangled and decoherent cases.