Polarimeter for High Energy Photons

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0072391Vlahovid In many research facilities such as JLAB, LEGS, GRAAL, DESY, SAL, MAMI, and INS, which have scheduled experiments with polarized photon beam, there is a need for accurate polarization measurements in short time periods. Unfortunately at present, no adequate method is available at the higher energies characteristic of such facilities. At energies above ~ 600 MeV all known method have small analyzing power, and significant amount of time is required for polarization measurements. At the lower energies the pair production method off nuclei isknown to be the most promising. However, because the opening angle between the electron-positron pair decreases as the energy of the photon increases, this method has not been applied to higher energies. We propose to improve the pair production method at lower energies, and to extend it to higher energies, by taking advantage of new development in microstrip detectors technologies. The proposed polarimeter will have an analyzing power of the ~ 1.7 for a broad energy range, from few MeV up to several GeV. The proposed polarimeter is simple in construction and its costs will be lower than for polarimeters built on any of the other availablemethods.