Modeling charge collection in silicon pixel detectors for proton therapy applications

Area of Science:

• Particle Physics
• Medical Physics
• Detector Technology

Background:

• Monolithic active pixel sensors are crucial for charged particle tracking in diverse fields.
• The ALICE PIxel DEtector (ALPIDE) is utilized in proton computed tomography (pCT) and particle therapy range verification.
• Accurate charge diffusion modeling is essential for interpreting energy deposition in pixel detectors.

Purpose of the Study:

• To optimize charge diffusion models for pCT and in-situ range verification using ALPIDE sensors.
• To evaluate the impact of different charge diffusion models on downstream application performance.
• To identify the most effective diffusion models for specific applications.

Main Methods:

• Experimental data from the Danish Centre for Particle Therapy was used for model optimization.
• Parameters of various charge diffusion models were fitted to experimental data.
• Downstream task performance was assessed to quantify the impact of charge diffusion modeling.

Main Results:

• Application-specific charge diffusion models yield superior results compared to generic models.
• A power law model demonstrated optimal performance for proton computed tomography.
• A 2D Cauchy-Lorentz distribution model provided better agreement for proton range verification.
• Evaluating downstream tasks with multiple approaches is critical for performance metric estimation.

Conclusions:

• Charge diffusion model selection significantly influences the performance of particle tracking applications.
• A 2D Cauchy-Lorentz distribution model is recommended for proton range verification with ALPIDE pixel telescopes.
• Optimized, application-specific diffusion models enhance the utility of ALPIDE-based pixel telescopes.