Energy-dispersive diffraction with synchrotron radiation and a germanium detector

Area of Science:

• Materials Science
• Crystallography
• Synchrotron Radiation Physics

Background:

• Intrinsic germanium (Ge) detectors are used in energy-dispersive diffraction (EDD) with synchrotron radiation.
• High-intensity synchrotron beams cause pulse pile-up in detectors, affecting spectral accuracy.
• The storage ring fill pattern significantly influences pile-up characteristics and observed spectra.

Purpose of the Study:

• To study the response of intrinsic Ge detectors in EDD measurements with synchrotron radiation.
• To develop and validate a model for correcting pulse pile-up effects in diffraction spectra.
• To assess the impact of pile-up on crystal structure analysis and potential misinterpretations.

Main Methods:

• Model calculations of detector response and diffraction from perfect silicon (Si) crystals.
• Analysis of pile-up distributions based on synchrotron storage ring fill patterns (e.g., 16-bunch, 1/3 fill).
• Refinement of model parameters by fitting to observed energy spectra from Si wafers.

Main Results:

• Pile-up distributions are characteristic of the storage ring fill pattern, showing single or multiple peaks.
• A validated model successfully corrected pile-up effects in Si crystal diffraction, achieving agreement with dynamical theory.
• Simulations show pile-up peaks can be mistaken for superlattices or phase transitions in powder diffraction.

Conclusions:

• The developed model effectively corrects for pulse pile-up in Ge detectors for EDD.
• Accurate corrections enable precise analysis of crystal structures and validate diffraction theories.
• Careful consideration of pile-up is crucial to avoid misinterpreting diffraction data, especially in strain mapping.