Coherent bremsstrahlung, coherent pair production, birefringence and polarimetry in the 20-170 GeV energy range using aligned crystals

Abstract

The processes of coherent bremsstrahlung (CB) and coherent pair production (CPP) based on aligned crystal targets have been studied in the energy range 20-170 GeV. The experimental arrangement allowed for measurements of single photon properties of these phenomena including their polarization dependences. This is significant as the theoretical description of CB and CPP is an area of active theoretical debate and development. With the theoretical approach used in this paper both the measured cross sections and polarization observables are predicted very well. This indicates a proper understanding of CB and CPP up to energies of 170 GeV. Birefringence in CPP on aligned crystals is applied to determine the polarization parameters in our measurements. New technologies for high energy photon beam optics including phase plates and polarimeters for linear and circular polarization are demonstrated in this experiment. Coherent bremsstrahlung for the strings-on-strings (SOS) orientation yields a larger enhancement for hard photons than CB for the channeling orientations of the crystal. Our measurements and our calculations indicate low photon polarizations for the high energy SOS photons.

23 pages, 27 figures, 2 tables, REVTeX4 two columns

References in corpus (7)

• Measuring Polarized Gluon and Quark Distributions with Meson Photoproduction
• Results on the Coherent Interaction of High Energy Electrons and Photons in Oriented Single Crystals
• Improved Crystal Method for Photon Beam Linear Polarization Measurement at High Energies
• Emission of polarized photons from unpolarized electrons moving in crystals
• Computer simulation of coherent interaction of charged particles and photons with crystalline solids at high energies
• Propagation of polarized high-energy photons in crystals
• Hard Polarized Photon Emission in Single Crystals by High Energy Electrons for Planar Crystal Orientations

Cited by in corpus (5)

• Production of Highly Polarized Positron Beams via Helicity Transfer from Polarized Electrons in a Strong Laser Field
• High-energy gamma-photon polarization in nonlinear Breit-Wheeler pair production and gamma-polarimetry
• Coherent bremsstrahlung in periodically deformed crystals with a complex base
• Photoproduction of electron-positron pairs in bent single crystals
• Polarization of bremsstrahlung at electron scattering in an anisotropic medium