Performance Model for High Spatial Resolution Csl Scintillator Screens Coupled to CCD Detectors

Area of Science:

• * X-ray imaging
• * Crystallography
• * Detector physics

Background:

• * Development of an x-ray imaging camera at York University for recording crystallographic diffraction patterns.
• * Camera utilizes charge-coupled device (CCD) sensors coupled to a CsI(Tl) x-ray scintillator via fiber optic tapers.

Purpose of the Study:

• * To present a performance model for the developed x-ray imaging camera.
• * To predict the accuracy of diffraction spot intensity measurements across various incident x-ray flux levels.

Main Methods:

• * Development of a performance model incorporating scintillator and optics point spread functions.
• * Inclusion of typical diffraction spot geometry in the model.
• * Analysis of camera performance at x-ray energies above the scintillator K absorption edge (>33 keV).

Main Results:

• * The model predicts diffraction spot intensity measurement accuracy as a function of incident x-ray flux.
• * Point spread function and spot geometry significantly impact performance at low intensities, limiting dynamic range.
• * Quantum-limited performance is achievable for incident dose fluxes as low as 100 photons per spot.
• * Energy loss via K-shell fluorescent escape photons reduces detective quantum efficiency above 33 keV.

Conclusions:

• * The developed performance model accurately predicts the capabilities of the new x-ray imaging camera.
• * System design allows for quantum-limited performance at low photon fluxes, crucial for crystallographic applications.
• * Understanding limitations such as point spread function and energy loss is key for optimizing detector performance.