Gepta-EX: a multi-channel germanium detector for X-ray absorption fine structure

Area of Science:

• Materials Science
• Spectroscopy
• Detector Physics

Background:

• High-energy fluorescence-mode X-ray absorption spectroscopy (XAS) demands detectors with high stopping power and energy resolution.
• Silicon detectors lack efficiency above 20 keV, while other high-Z materials are optimized for imaging, not spectroscopy.

Purpose of the Study:

• To develop and evaluate a compact, multi-channel high-purity germanium (HPGe) detector system for high-energy XAS.
• To overcome the limitations of existing detectors for weak signal detection in XAS.

Main Methods:

• Fabrication of a monolithic seven-channel HPGe pixel array.
• Integration with low-noise CUBE charge-sensitive preamplifiers.
• Operation within a compact, thermally isolated cryostat near 90 K.

Main Results:

• The Gepta-EX system demonstrated excellent energy resolutions: 218 eV at 5.9 keV and 373 eV at 59.5 keV.
• Uniform performance was achieved across all seven channels.
• The detector avoids escape peak interference common in silicon detectors.

Conclusions:

• Gepta-EX provides stable, high-resolution performance for high-energy X-ray spectroscopy.
• This HPGe detector system is a powerful new tool for fluorescence-mode XAS.
• It enables more precise measurements of element-specific signals in challenging energy ranges.