Carbon-14 is primarily created in the upper atmosphere through a nuclear reaction involving cosmic rays and nitrogen atoms.
Here's a breakdown of the process:
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Cosmic Ray Interaction: High-energy cosmic rays, which are particles originating from outside the solar system, constantly bombard the Earth's atmosphere.
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Neutron Production: When cosmic rays collide with atoms in the atmosphere, they produce secondary particles, including neutrons. These neutrons are referred to as thermal neutrons.
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Nitrogen Conversion: These thermal neutrons collide with nitrogen-14 (14N) atoms, which are abundant in the atmosphere. This collision initiates a nuclear reaction where the nitrogen-14 atom absorbs a neutron and emits a proton.
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Carbon-14 Formation: The nuclear reaction transforms the nitrogen-14 atom into a carbon-14 (14C) atom. The equation for this reaction is:
14N + n → 14C + p
Where:
- 14N is nitrogen-14
- n is a neutron
- 14C is carbon-14
- p is a proton
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Location: This process occurs primarily in the stratosphere, approximately 10 to 13 miles above Earth's poles, where the cosmic ray flux is highest.
In addition to natural production, atmospheric nuclear weapons testing in the 1950s and 1960s also significantly increased the amount of carbon-14 in the atmosphere. This "bomb pulse" is now used as a dating tool in some specific research areas.
