A pair polarimeter for linearly polarized high-energy photons

Electron–positron pair production, the main process for high-energy photon interaction with matter, has a large analyzing power for linear polarized photons. Our calculations show that in the GeV energy range a compact polarimeter based on silicon micro-strip detectors is feasible. We calculated the cross-section as a function of the angle between the polarization plane and the line between positron and electron positions in the detector. For a thin radiator and equal energies of the positron and electron the ratio σ∥/σ⊥ is about 1.6. At a beam intensity of 106 photons per second, a polarization measurement with a 1% statistical accuracy will require less than 1 h of data taking.