Re-construction of a HPGe detector precise modeling for efficiency calibration

Area of Science:

• Nuclear Physics
• Detector Technology
• Fusion Energy Research

Background:

• High purity germanium (HPGe) detectors are essential for radioactive sample activity measurement in Inertial Confinement Fusion (ICF) diagnostics.
• Activity measurements often require close detector-source distances, posing challenges for efficiency calibration due to coincidence effects.

Purpose of the Study:

• To develop a precise model of HPGe detectors for accurate efficiency calibration.
• To overcome limitations of close-distance measurements by enabling efficiency calculations at arbitrary distances.

Main Methods:

• Utilized X-ray radiography and 3D reconstruction to determine internal HPGe detector geometry.
• Employed Monte Carlo simulations for efficiency calculations.
• Optimized germanium crystal dead layers by minimizing the sum squared residual (SSR) between calculated and measured gamma-ray efficiencies.

Main Results:

• A corrected HPGe detector model was established, incorporating non-homogeneous dead layer distributions.
• The model significantly improved the accuracy of calculated gamma-ray efficiencies.
• This approach provides a reliable method for efficiency calibration at various distances.

Conclusions:

• The developed precise HPGe detector model enhances the accuracy of efficiency calculations, crucial for ICF nuclear diagnostics.
• X-ray radiography and Monte Carlo simulations offer a robust alternative to traditional calibration methods.
• Accurate efficiency calibration is key to reliable radioactive sample analysis in fusion research.