BOMB
SPIKE

ISOCORE, during its activity on AMS ¹⁴C dating, achieved high precision measurements opening the opportunity to forensic applications and authentications using the so called bomb ¹⁴C. This is due to nuclear weapon tests which were performed in the atmosphere in the years 50-60 of last century.

Nuclear reactions induced by the intense neutron emissions accompanying the explosions strongly increased the amount of ¹⁴C in the atmosphere which was rapidly mixed by large scale circulation and leveled out in the northern hemisphere, reaching a value of the isotopic ratio ¹⁴C/¹²C doubled with respect to the pre-bomb value . After the signature of the Nuclear Ban Treaty in 1963, which hampered detonations in the atmosphere, this ratio began a rapid decrease due to the dilution of the atmospheric ¹⁴C in the hydrosphere and the biosphere.

The rate of this decrease, much faster than that due to radioactive decay, allows the dating of specimens belonging to organisms that ceased their C exchange with the atmosphere after 1950 AD with a much smaller uncertainty (in some cases less than one year) than in the previous time span. This paved the way to the utilization of the so called bomb spike dating in forensic applications and of the biogenic-fossil fraction in samples of several different use, from plastic bags to tires, from biomasses to fuel.