Determination of HPGe peak efficiency for voluminous gamma-ray sources by using an effective solid angle method

Area of Science:

• Nuclear Physics
• Radiation Detection and Measurement

Background:

• Accurate determination of absolute peak efficiency is crucial for quantifying gamma-ray emissions from extended sources.
• Existing methods may have limitations in handling complex geometries and matrix effects.
• High-purity germanium (HPGe) detectors are widely used for gamma-ray spectroscopy.

Purpose of the Study:

• To develop and validate a computational code (EXVol) for calculating absolute peak efficiency of voluminous gamma-ray sources.
• To assess the impact of geometric and matrix effects on detection efficiency.
• To compare the performance of EXVol with existing methods and experimental data.

Main Methods:

• Development of the EXVol code based on the effective solid angle concept.
• Semi-empirical determination of efficiency curves for voluminous sources.
• Experimental measurements using certified reference volume sources with HPGe detectors of varying efficiencies.
• Analysis of geometric and matrix effects using sources of different media, volumes, and shapes.

Main Results:

• The EXVol code calculates detection efficiency for voluminous sources with relative deviations generally less than ±10% for an n-type HPGe detector (32% relative efficiency).
• The code's performance is comparable to existing software for similar applications.
• EXVol can compute detection efficiency in approximately five minutes or less.
• Systematic errors related to detector dimensions were investigated to improve accuracy.

Conclusions:

• EXVol provides a fast and accurate method for determining absolute peak efficiency of voluminous gamma-ray sources.
• The code effectively accounts for geometric and matrix effects, crucial for accurate source quantification.
• Further investigation into detector parameter uncertainties can enhance the precision of EXVol calculations.