title: A phase-space beam position monitor for synchrotron radiation.
abstract: The stability of the photon beam position on synchrotron beamlines is critical for most if not all synchrotron radiation experiments. The position of the beam at the experiment or optical element location is set by the position and angle of the electron beam source as it traverses the magnetic field of the bend-magnet or insertion device. Thus an ideal photon beam monitor would be able to simultaneously measure the photon beam's position and angle, and thus infer the electron beam's position in phase space. X-ray diffraction is commonly used to prepare monochromatic beams on X-ray beamlines usually in the form of a double-crystal monochromator. Diffraction couples the photon wavelength or energy to the incident angle on the lattice planes within the crystal. The beam from such a monochromator will contain a spread of energies due to the vertical divergence of the photon beam from the source. This range of energies can easily cover the absorption edge of a filter element such as iodine at 33.17 keV. A vertical profile measurement of the photon beam footprint with and without the filter can be used to determine the vertical centroid position and angle of the photon beam. In the measurements described here an imaging detector is used to measure these vertical profiles with an iodine filter that horizontally covers part of the monochromatic beam. The goal was to investigate the use of a combined monochromator, filter and detector as a phase-space beam position monitor. The system was tested for sensitivity to position and angle under a number of synchrotron operating conditions, such as normal operations and special operating modes where the photon beam is intentionally altered in position and angle at the source point. The results are comparable with other methods of beam position measurement and indicate that such a system is feasible in situations where part of the synchrotron beam can be used for the phase-space measurement.
authors.affiliation: Biomedical Engineering, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK, Canada S7N 5E5.
authors.forename: Nazanin
authors.initials: N
authors.lastname: Samadi
authors.affiliation: Physics and Engineering Physics, University of Saskatchewan, 116 Science Place, Saskatoon, SK, Canada S7N 5E2.
authors.forename: Bassey
authors.initials: B
authors.lastname: Bassey
authors.affiliation: Physics and Engineering Physics, University of Saskatchewan, 116 Science Place, Saskatoon, SK, Canada S7N 5E2.
authors.forename: Mercedes
authors.initials: M
authors.lastname: Martinson
authors.affiliation: Canadian Light Source, 44 Innovation Boulevard, Saskatoon, SK, Canada S7N 2V3.
authors.forename: George
authors.initials: G
authors.lastname: Belev
authors.affiliation: Canadian Light Source, 44 Innovation Boulevard, Saskatoon, SK, Canada S7N 2V3.
authors.forename: Les
authors.initials: L
authors.lastname: Dallin
authors.affiliation: Canadian Light Source, 44 Innovation Boulevard, Saskatoon, SK, Canada S7N 2V3.
authors.forename: Mark
authors.initials: M
authors.lastname: de Jong
authors.affiliation: Anatomy and Cell Biology, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK, Canada S7N 5E5.
authors.forename: Dean
authors.initials: D
authors.lastname: Chapman
mesh_terms: D018360:Crystallography, X-Ray; D017785:Photons; D017356:Synchrotrons
keywords: K-edge absorption; X-ray diffraction; beam position monitor; phase space