LET, track structure and models. A review.

Area of Science:

• Physics
• Radiation Biology
• Materials Science

Background:

• Swift heavy ions interact with matter by stripping electrons, creating an effective charge.
• This effective charge drives excitation and ionization of target atoms, leading to energy deposition.
• The energy loss process generates secondary electrons that form a particle track around the ion's trajectory.

Purpose of the Study:

• To accurately calculate energy loss and linear energy transfer (LET) for swift heavy ions.
• To model the spatial distribution of energy deposition within particle tracks.
• To improve the agreement between theoretical models and experimental observations of radiation damage.

Main Methods:

• Utilized the Bethe Bloch formula for energy loss and the Barkas formula for effective charge.
• Calculated energy loss, unrestricted and restricted linear transfer with high accuracy.
• Developed and refined track structure models, incorporating continuous dose distribution and cellular repair capacity.

Main Results:

• Energy loss is primarily used for ionization, with a small fraction for excitation.
• Secondary electrons transport energy radially, creating a dose distribution that decreases with distance.
• Track diameter is independent of effective charge but dose increases with the square of effective charge.

Conclusions:

• Track structure models provide better agreement with experimental data than microdosimetry models.
• The inclusion of cellular repair capacity in track structure models yields the best agreement with experimental results.
• These refined models are crucial for understanding and predicting biological effects of heavy ion radiation.