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Determination of X-ray flux using silicon pin diodes.

Owen RL, Holton JM, Schulze-Briese C, Garman EF - J Synchrotron Radiat (2009)

Bottom Line: Accurate measurement of photon flux from an X-ray source, a parameter required to calculate the dose absorbed by the sample, is not yet routinely available at macromolecular crystallography beamlines.These experiments have shown that a simple model based on energy deposition in silicon is sufficient for determining the flux incident on high-quality silicon pin diodes.The derivation and validation of this model is presented, and a web-based tool for the use of the macromolecular crystallography and wider synchrotron community is introduced.

View Article: PubMed Central - HTML - PubMed

Affiliation: Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland.

ABSTRACT
Accurate measurement of photon flux from an X-ray source, a parameter required to calculate the dose absorbed by the sample, is not yet routinely available at macromolecular crystallography beamlines. The development of a model for determining the photon flux incident on pin diodes is described here, and has been tested on the macromolecular crystallography beamlines at both the Swiss Light Source, Villigen, Switzerland, and the Advanced Light Source, Berkeley, USA, at energies between 4 and 18 keV. These experiments have shown that a simple model based on energy deposition in silicon is sufficient for determining the flux incident on high-quality silicon pin diodes. The derivation and validation of this model is presented, and a web-based tool for the use of the macromolecular crystallography and wider synchrotron community is introduced.

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The ratio of the corrected scintillator count rate to current produced in the S100VL diode plotted against photon energy. Red error bars indicate the root-mean-square scatter of ten back-and-forth comparisons corrected for dead-time and window transmissions [equation (4)] while the blue line is the theoretical photoconversion ratio of the diode [equation (2)]. The theoretical photoconversion ratio is overlaid on the comparison, not fitted to the data. Note that the scatter in measured values is much greater at lower incident X-ray energies owing to the instability of the highly attenuated beam.
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fig5: The ratio of the corrected scintillator count rate to current produced in the S100VL diode plotted against photon energy. Red error bars indicate the root-mean-square scatter of ten back-and-forth comparisons corrected for dead-time and window transmissions [equation (4)] while the blue line is the theoretical photoconversion ratio of the diode [equation (2)]. The theoretical photoconversion ratio is overlaid on the comparison, not fitted to the data. Note that the scatter in measured values is much greater at lower incident X-ray energies owing to the instability of the highly attenuated beam.

Mentions: The proposed flux calculation model was applied to the S100VL diode characterized in §3.1. Fig. 5 ▶ shows the theoretical photoconversion ratio of the diode [equation (2)] in addition to the experimentally determined photoconversion ratio which was determined from comparison with the scintillator. The theoretical photoconversion ratio (blue line) is a superposition rather than a fit to the experimental data, illustrating the excellent agreement between the simple model and the experimental results.


Determination of X-ray flux using silicon pin diodes.

Owen RL, Holton JM, Schulze-Briese C, Garman EF - J Synchrotron Radiat (2009)

The ratio of the corrected scintillator count rate to current produced in the S100VL diode plotted against photon energy. Red error bars indicate the root-mean-square scatter of ten back-and-forth comparisons corrected for dead-time and window transmissions [equation (4)] while the blue line is the theoretical photoconversion ratio of the diode [equation (2)]. The theoretical photoconversion ratio is overlaid on the comparison, not fitted to the data. Note that the scatter in measured values is much greater at lower incident X-ray energies owing to the instability of the highly attenuated beam.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2651761&req=5

fig5: The ratio of the corrected scintillator count rate to current produced in the S100VL diode plotted against photon energy. Red error bars indicate the root-mean-square scatter of ten back-and-forth comparisons corrected for dead-time and window transmissions [equation (4)] while the blue line is the theoretical photoconversion ratio of the diode [equation (2)]. The theoretical photoconversion ratio is overlaid on the comparison, not fitted to the data. Note that the scatter in measured values is much greater at lower incident X-ray energies owing to the instability of the highly attenuated beam.
Mentions: The proposed flux calculation model was applied to the S100VL diode characterized in §3.1. Fig. 5 ▶ shows the theoretical photoconversion ratio of the diode [equation (2)] in addition to the experimentally determined photoconversion ratio which was determined from comparison with the scintillator. The theoretical photoconversion ratio (blue line) is a superposition rather than a fit to the experimental data, illustrating the excellent agreement between the simple model and the experimental results.

Bottom Line: Accurate measurement of photon flux from an X-ray source, a parameter required to calculate the dose absorbed by the sample, is not yet routinely available at macromolecular crystallography beamlines.These experiments have shown that a simple model based on energy deposition in silicon is sufficient for determining the flux incident on high-quality silicon pin diodes.The derivation and validation of this model is presented, and a web-based tool for the use of the macromolecular crystallography and wider synchrotron community is introduced.

View Article: PubMed Central - HTML - PubMed

Affiliation: Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland.

ABSTRACT
Accurate measurement of photon flux from an X-ray source, a parameter required to calculate the dose absorbed by the sample, is not yet routinely available at macromolecular crystallography beamlines. The development of a model for determining the photon flux incident on pin diodes is described here, and has been tested on the macromolecular crystallography beamlines at both the Swiss Light Source, Villigen, Switzerland, and the Advanced Light Source, Berkeley, USA, at energies between 4 and 18 keV. These experiments have shown that a simple model based on energy deposition in silicon is sufficient for determining the flux incident on high-quality silicon pin diodes. The derivation and validation of this model is presented, and a web-based tool for the use of the macromolecular crystallography and wider synchrotron community is introduced.

Show MeSH
Related in: MedlinePlus