A simple polarimeter for quantifying synchrotron polarization

There are currently no simple and easy to apply techniques for determining the degree of linear polarization of a soft X-ray beam delivered by a synchrotron beamline despite the fact that this parameter is important for a wide range of synchrotron-based soft X-ray experiments. This work presents a new method for the quantitative determination of the linear polarization state of synchrotron radiation using an HOPG crystal as the standard sample. The method is straightforward to perform without the need for experimental apparatus beyond that commonly available at beamlines in this energy range. In addition, the high-degree of order that can easily be achieved in a HOPG sample means that it is potentially more accurate than currently employed comparative methods. We show how the method can be applied to experimentally determine the linear polarization state of various soft X-ray synchrotron beamlines and we discuss the wide variations in the degree of linear polarization that are measured.