Detection of Radioactive Materials Using Carbon-Dioxide Lasers

A groundbreaking technique has been developed by U.S. physicists to detect radioactive materials from a distance using carbon-dioxide lasers. This method has significant implications for national defense and emergency response, emphasizing the importance of safe and accurate detection.

Key Techniques and Phenomena

• Avalanche Breakdown:
  • Occurs when radioactive decay releases charged particles that ionize air, creating plasma.
  • Electrons, or seeds, are accelerated to collide and release more electrons, enhancing the ionization effect.
• Carbon-Dioxide Lasers:
  • Lasers emitting long-wave infrared radiation at 9.2 micrometres are used to accelerate electrons.
  • Can detect alpha particles from a source 10 meters away, improving previous detection ranges by a factor of 10.

Advantages of Long-Wavelength Lasers

• Drive electron avalanches crucial for detecting low concentrations of seed electrons.
• Reduce undesirable ionization effects, enhancing detection sensitivity.

Experimental Enhancements

• Fluorescence imaging was used to analyze plasma dynamics and seed density profiles.
• Mathematical modeling accurately predicted backscatter signals, validating the detection technique.

Future Prospects and Challenges

• Potential to detect gamma-ray sources like caesium-137 from up to 100 meters away.
• Challenges include the need for larger optics and higher laser energies for detection at distances around 1 km.
• Detection methods may be limited due to background radiation and atmospheric interference at extended ranges.