"After 1955 the level of radiocarbon in the atmosphere, and thus in living organisms, almost doubled in about 10 years," Pier Andrea Mandò, head of the Florence division of the INFN, explained in a statement.
"It is due to this rapid change that works from those years can be dated extremely accurately," Mandò added.
For example, in the year 2000, the modern standard activity will have declined from 0.227 Becquerels/gram to 0.225 Becquerels/gram.
Cosmic ray particles are predominantly high energy protons and 4He nuclei ( α -particles).
Part of the cosmic ray flux originates at the sun, and is generated by solar flare events. The mechanisms giving rise to the highest energy cosmic rays are not well understood.
[Faux Real: A Gallery of Forgeries] To solve this art historical enigma, scientists from the Italian Institute for Nuclear Physics (INFN) took a tiny piece of the canvas from an unpainted edge of the work.
The team used a particle accelerator to measure the concentration of carbon 14 (an isotope of carbon that has more neutrons than normal carbon 12) in the fabric, which would in turn allow them to determine when the canvas was produced, or more specifically, when the cotton was cut to make the canvas.