Carbon-dioxide Lasers

Carbon-dioxide Lasers: A team of U.S. physicists has successfully demonstrated a new technique to detect radioactive materials using carbon-dioxide lasers from a distance.

• About Carbon-dioxide Lasers: The technique involves a phenomenon called avalanche breakdown, where charged particles released during radioactive decay ionise the air, creating plasma.

o Electrons are accelerated to collide with other atoms, releasing more electrons in a chain reaction, known as avalanche breakdown.

o Researchers used a carbon-dioxide laser emitting long-wave infrared radiation at a wavelength of 9.2 micrometres to accelerate the electrons.

o The experiment successfully detected alpha particles from a radioactive source 10 meters away, improving the range by a factor of 10 compared to previous experiments.

o The laser-induced electrons (called seeds) create microplasma balls in the air, generating optical backscatter, which can be amplified for better detection sensitivity.

• Advantages of Using Long-wavelength Lasers: Long-wavelength lasers can drive electron avalanches, allowing the detection of very low concentrations of seed electrons.

o Longer wavelengths reduce undesirable ionisation effects that could interfere with detection signals.