Physicists Accidentally Turn Lead Into Gold at CERN

Alchemists dreamed of it for centuries: turning lead into gold. Now physicists at CERN have actually done it - by accident, in microscopic amounts, and in a way that will make nobody rich.

Researchers on the ALICE experiment at the Large Hadron Collider in Switzerland produced gold when they fired lead nuclei past each other at nearly the speed of light. Their goal was not to make precious metal but to recreate conditions just after the Big Bang.

Lead and gold differ by just three protons: a lead atom has 82 protons in its nucleus, gold has 79. Strip exactly three protons away and, in theory, a gold nucleus remains - and that is occasionally what happened. When lead nuclei skim past each other, their enormous electric fields can tear protons loose. One proton lost yields thallium, two yield mercury, three yield gold.

The yield was impressive scientifically but financially pointless: an estimated 89,000 gold nuclei formed per second, totalling about 29 trillionths of a gram over the whole research period. Even if it could all be collected - which it cannot - the value would be negligible, while running the LHC costs vastly more.

For the researchers the gold is not even a bonus, but an annoying side effect. A lead nucleus that loses protons no longer follows its precisely calculated path in the vacuum tube, crashing into the wall within microseconds and gradually degrading the beam. Understanding the process helps them interpret current experiments and design future, more powerful accelerators.

A medieval alchemist would be baffled: turning lead into gold is possible, but it requires one of the largest and most expensive machines on Earth - and yields almost nothing. The real gain is knowledge about extreme electromagnetic fields and the state of matter in the young universe.