A photon beam polarimeter based on nuclear e+e- pair production in an amorphous target

To directly measure the linear polarization of coherent bremsstrahlung (CB) photons with a peak energy of 1 GeV at the Yerevan synchrotron, a simple polarimeter is proposed based on a e+e- pair spectrometer equipped with two hodoscopes of scintillating counters positioned above and below of the median plane, configured to detect symmetric pairs produced in an amorphous target. Monte Carlo calculations show that the use of a vertical slit collimator at the entrance of the magnet improves both the analyzing power and the energy resolution. The values of the analyzing power for various atomic form factors of the target (the 20μm of aluminum) reach a 0.25-0.28 with expected yields of useful events on the level of a few Hz at nominal operating intensity.