Ionisation cluster-size formation by electrons: from macroscopic to nanometric target sizes

Area of Science:

• Physics
• Chemistry
• Biology
• Radiation Science

Background:

• Detailed knowledge of particle track structure is crucial for understanding radiation effects on matter.
• Electron tracks are of particular interest as secondary particles generated by ionizing radiation.
• Low-energy electrons (few hundred eV) are most effective in inducing DNA double-strand breaks.

Purpose of the Study:

• Investigate electron track structure properties.
• Analyze ionisation cluster-size formation as a function of target size.
• Focus on the transition from macroscopic to nanometric target volumes.

Main Methods:

• Simulations of electron tracks in liquid water.
• Analysis of ionisation cluster-size distributions.
• Varying target sizes from macroscopic to nanometric scales.

Main Results:

• The probability of forming ionisation clusters (≥2) is highest for electrons at a few hundred eV.
• This effect is pronounced in nanometric water cylinders (2 nm diameter/height), mimicking DNA segments.
• Cluster-size distributions show distinct behavior as target size decreases.

Conclusions:

• Low-energy electrons and their ionisation cluster formation in nanometric targets provide insights into radio-biological endpoints.
• Understanding these nanometric effects is essential for predicting early DNA and cellular damage.
• The study highlights the importance of target size in electron track structure analysis.