Determination of the linear polarization for pseudo-scalar meson photoproduction experiments in Hall-B at JLab*

The JLab CLAS g9a experiments are double polarization measurements that have accumulated photoproduction data using a linearly polarized, tagged photons incident on a longitudinally polarized, frozen spin butanol target (FROST). Linearly polarized photons were produced via coherent bremsstrahlung from an electron beam incident on an oriented diamond crystal.\footnote{U. Timm, Fortschritte der Physik, \textbf{17}, 765 (1969).} The analysis of the resulting coherent peaks was used to determine photon polarization which agree with phenomenological calculations.\footnote{A. Natter, \textit{et al.}, Nuc. Inst Meth B \textbf{211}, 465 (2003).}