2015 CAP Congress / Congrès de l'ACP 2015

A Phase Space Beam Position Monitor for Synchrotron Radiation

15 Jun 2015, 16:30

15m

CCIS L1-047 (University of Alberta)

Oral (Student, In Competition) / Orale (Étudiant(e), inscrit à la compétition) Instrumentation and Measurement Physics / Physique des instruments et mesures (DIMP-DPIM) M2-9 Advanced Instrumentation at Major Science Facilities: Accelerators (DIMP) / Instrumentation avancée dans des installations scientifiques majeures: accélérateurs (DPIM)

Speaker

Nazanin Samadi (University of Saskatchewan)

Description

Synchrotron radiation experiments critically depend on the stability of the photon beam position. The position of the photon beam at the experiment or optical element location is set by the electron beam source position and angle as it traverses the magnetic field of the bend magnet or insertion device. An ideal photon beam monitor would be able to measure the photon beam’s position and angle, and thus infer the electron beam’s position in phase space. Monochromatic x-ray beams at synchrotrons are typically prepared by x-ray diffraction from crystals 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 with and without the filter can be used to determine the vertical angle and position of the photon beam. In these measurements an imaging detector measures these vertical profiles with an iodine filter that horizontally covers part of the monochromatic beam. The goal was to investigate the use of this 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 beam is intentionally altered in position and angle. The results are comparable to other methods of beam position measurements and indicate that such a system is feasible in situations where part of the white synchrotron beam can be used for the phase space measurement.