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A phase-space beam position monitor for synchrotron radiation.

Samadi N, Bassey B, Martinson M, Belev G, Dallin L, de Jong M, Chapman D - J Synchrotron Radiat (2015)

Bottom Line: Diffraction couples the photon wavelength or energy to the incident angle on the lattice planes within the crystal.This range of energies can easily cover the absorption edge of a filter element such as iodine at 33.17 keV.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.

View Article: PubMed Central - HTML - PubMed

Affiliation: Biomedical Engineering, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK, Canada S7N 5E5.

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.

No MeSH data available.


Calculated flux through a 60 mg cm−2 iodine filter from a Si (2,2,0) DCM at 33.17 keV on a CLS bend-magnet beamline.
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fig4: Calculated flux through a 60 mg cm−2 iodine filter from a Si (2,2,0) DCM at 33.17 keV on a CLS bend-magnet beamline.

Mentions: Schematically, the effect of an iodine filter on the transmitted beam of a DCM set at 33.17 keV is shown in Fig. 2(c) ▸. Note that the spectral content of the beam vertically increases in energy from the bottom of the beam to the top. When the middle energy of the beam is placed at the iodine K-edge then the top of the beam will be absorbed more than the bottom creating an asymmetric beam profile shown on the right side of the figure. A calculation of the beam shape including the DuMond dispersion effects is shown in Fig. 4 ▸.


A phase-space beam position monitor for synchrotron radiation.

Samadi N, Bassey B, Martinson M, Belev G, Dallin L, de Jong M, Chapman D - J Synchrotron Radiat (2015)

Calculated flux through a 60 mg cm−2 iodine filter from a Si (2,2,0) DCM at 33.17 keV on a CLS bend-magnet beamline.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4489536&req=5

fig4: Calculated flux through a 60 mg cm−2 iodine filter from a Si (2,2,0) DCM at 33.17 keV on a CLS bend-magnet beamline.
Mentions: Schematically, the effect of an iodine filter on the transmitted beam of a DCM set at 33.17 keV is shown in Fig. 2(c) ▸. Note that the spectral content of the beam vertically increases in energy from the bottom of the beam to the top. When the middle energy of the beam is placed at the iodine K-edge then the top of the beam will be absorbed more than the bottom creating an asymmetric beam profile shown on the right side of the figure. A calculation of the beam shape including the DuMond dispersion effects is shown in Fig. 4 ▸.

Bottom Line: Diffraction couples the photon wavelength or energy to the incident angle on the lattice planes within the crystal.This range of energies can easily cover the absorption edge of a filter element such as iodine at 33.17 keV.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.

View Article: PubMed Central - HTML - PubMed

Affiliation: Biomedical Engineering, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK, Canada S7N 5E5.

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.

No MeSH data available.