Validation of gamma scanning method for optimizing NaI(Tl) detector model in Monte Carlo simulation

Area of Science:

• Nuclear Physics and Instrumentation
• Computational Physics and Simulation

Background:

• Accurate modeling of sodium iodide (NaI(Tl)) detectors is crucial for reliable Monte Carlo simulations in nuclear science.
• Traditional methods may require extensive parameterization, necessitating validation through experimental techniques.

Purpose of the Study:

• To validate the gamma scanning method for optimizing NaI(Tl) detector models used in MCNP6 Monte Carlo simulations.
• To establish a reliable procedure for determining key physical parameters of NaI(Tl) detectors through experimental measurements.

Main Methods:

• Experimental gamma scanning of NaI(Tl) detector surfaces using a collimated photon beam.
• Efficiency calibration across a range of photon energies (31–1408 keV) using point sources at varying distances.
• Monte Carlo simulations using MCNP6, with model parameters adjusted based on experimental data (crystal dimensions, reflector density).

Main Results:

• The physical dimensions (diameter, length) of the NaI(Tl) crystal were determined using gamma scanning with a ²⁴¹Am source.
• Reflector density was optimized by matching simulated and measured efficiency ratios for ¹³³Ba gamma rays.
• The validated Monte Carlo model demonstrated good agreement with experimental measurements for detector efficiency and energy spectrum response.

Conclusions:

• The gamma scanning method provides an effective means for optimizing NaI(Tl) detector models in Monte Carlo simulations.
• Validated models enhance the accuracy of predicting detector responses, crucial for experimental data analysis and simulation-based research.
• This approach improves the reliability of simulations for various applications involving NaI(Tl) detectors.