Defining an equivalent geometry for Monte Carlo calculations of a high-purity Ge detector with high relative...

Area of Science:

• Nuclear Instrumentation
• Computational Physics
• Radiation Detection

Background:

• Accurate geometric information for high-purity germanium (HPGe) detectors is essential for reliable Monte Carlo simulations.
• Manufacturer-provided detector geometries are often insufficient or invalid for precise simulation purposes.
• Existing simulation models lack optimized equivalent geometries for large-volume HPGe detectors.

Purpose of the Study:

• To develop an optimized equivalent geometry for a large-volume HPGe detector suitable for Monte Carlo simulations.
• To improve the accuracy of Monte Carlo simulations by refining detector geometry parameters.
• To investigate the necessity of adjusting crystal dimensions for accurate simulation of HPGe detectors.

Main Methods:

• Utilized a genetic algorithm to optimize detector geometry parameters.
• Employed a mixed-point gamma calibration standard with 12 gamma-ray energies (59.5–1836.1 keV).
• Calibrated the detector at 74 different positions around the HPGe detector to gather experimental efficiency data.

Main Results:

• Achieved relative errors below 5% for high energies and 7% for lower energies (excluding 59.5 keV) using the optimized geometry.
• The optimized equivalent geometry significantly enhances the accuracy of Monte Carlo simulations.
• Demonstrated that using reduced crystal dimensions in simulations is necessary for high-volume HPGe detectors.

Conclusions:

• The genetic algorithm successfully optimized an equivalent geometry for HPGe detector Monte Carlo simulations.
• The optimized geometry yields accurate efficiency calculations, validating its effectiveness.
• Adjusting crystal dimensions in simulations is a critical factor for accurately modeling large-volume HPGe detectors and achieving experimental efficiency.