Medieval alchemists envisioned transmuting lead into gold. Now, this quest has taken on a new dimension at the Large Hadron Collider (LHC). CERN researchers have accomplished an amazing feat by creating a miniscule amount of metallic gold nuclei. They did this by achieving, through high-energy collisions of lead atoms, an unprecedented rate of nearly 89,000 nuclei per second. This extraordinary, groundbreaking result extends the frontiers of nuclear physics to the limit. It achieves that purpose and the deeper ambition of inspiring the historical dreams of alchemists who wanted to turn base metals into gold.
As both heavy metals, lead and gold are closely related elements that sit next to one another on the periodic table. For that reason, gold, with its 79 protons, is a more stable configuration than lead, which has three more protons. Medieval alchemists were obsessed with chrysopoeia, the ability to transform base metals into precious ones. They were largely motivated by a heady cocktail of scientific ambition barreled over by the promise of untold riches. Doing so would require actually removing three protons and a handful of neutrons from lead.
With the help of powerful particle accelerators such as the LHC, scientists can recreate these conditions in a laboratory environment. During the most recent run of the LHC, scientists pushed more powerful collisions to their limits. This historic experiment did create a tiny amount of gold—29 trillionths of a gram, to be precise. Gold nuclei collide with the narrow beam pipe and leave fragments in its wake—literally evaporating in less than a second. This extremely fast process makes it very difficult to observe them.
Scientists employed the ALICE Zero Degree Calorimeters (ZDCs) for proton and neutron spectroscopy. Specifically, they looked at those produced in the effort to produce gold itself. Uliana Dmitrieva noted the significance of this technological advancement:
“Thanks to the unique capabilities of the ALICE ZDCs, the present analysis is the first to systematically detect and analyze the signature of gold production at the LHC experimentally.”
The LHC’s third run has provided spectacular results, including a ten-fold factor increase in gold production. It did this almost double the rate produced in previous tests, due to increased energy levels. John Jowett commented on the broader implications of this research:
“The results also test and improve theoretical models of electromagnetic dissociation which, beyond their intrinsic physics interest, are used to understand and predict beam losses that are a major limit on the performance of the LHC and future colliders.”
Marco van Leeuwen expressed his admiration for the capabilities of their detection systems:
“It is impressive to see that our detectors can handle head-on collisions producing thousands of particles, while also being sensitive to collisions where only a few particles are produced at a time, enabling the study of rare electromagnetic ‘nuclear transmutation’ processes.”
