MEASUREMENTS OF THE POLARIZATION CORRELATION OF THE TWO-PHOTON SYSTEM PRODUCED IN POSITRON-ELECTRON ANNIHILATION

摘要

We present measurements of the polarization correlation of the two-photonsystem produced in positron-electron annihilation of (64)~Cu that were conducted at Freiburg University 1976-1980. Our experiment was motivated by two contradicting results. An experiment conducted at Columbia University observed a quantum mechanical correlation whereas an experiment conducted in Catania, Sicily observed a correlation that was about 40% lower. The two back-to-back photons are either both right-handed or left-handed polarized. The polarization of each photon is measured with a Compton polarimeter on each side of the source consisting of a plastic scintillator as scatterer and a NaI detector, which records the Compton-scattered photons.The polarization correlation is measured by the difference in azimuth angle Φ between the two polarimeters. We performed the measurements for different scatterer shapes, different scattering angles and different distances between the source and the polarimeters. We developed a detailed MonteCarlo program for simulating the quantum mechanical expectation for each measurement setup. All measurements agree rather well with quantum mechanics. We further reproduced the results of all conducted experiments with our simulation. The reduced Polarization correlation observed by the Sicilian experiment originated from a large fraction of double scattering in which the original polarization correlation is diminished. We further performed a test of Bells inequality with our results and those measured by other experiments.