Several centuries ago, a branch of alchemy called chrysopoeia is said to have explored the possibilities of transforming widely available base metals into precious metals. Early practitioners never managed to pull it off, but it appears that in studying the conditions that emerged just after the Big Bang using the Large Hadron Collider (LHC), scientists have turned lead into gold – for just fractions of a second.
Before you get too excited and start looking into investing in the LHC as a new asset class, it wasn’t a whole lot of gold. In fact, it was “trillions of times less than would be required to make a piece of jewelry.” But you can still marvel at the fact that one element transformed into another with distinctly different properties, through a new mechanism.
Before we dive into the how, let’s recap where it took place. The LHC is the world’s largest and most powerful particle accelerator: a circular tunnel where scientists smash tiny particles together at incredible speeds. The tunnel is 17 miles (27 km) in circumference, and is located in Geneva, Switzerland.
This facility is used to test theoretical predictions in particle physics, get a better sense of how the forces in our universe work, and understand the Big Bang.
The LHC goes through “runs,” or operational periods when the collider is actively accelerating and colliding particles for scientific experiments. Run 1 (2010-2013) culminated in the discovery of the Higgs boson particle.
Run 2 took place between 2015 and 2018, and was crucial in refining our understanding of the Standard Model of particle physics, as well as probing the properties of the Higgs boson with greater detail.
Now within the LHC complex, you’ve got ALICE, short for A Large Ion Collider Experiment. It refers to a specific detector and research program at the facility, and is focused on the physics of strongly interacting matter.
CERN
The idea is to study the conditions thought to have existed immediately after the Big Bang by measuring the properties of what’s called quark-gluon plasma.
When you have high-energy collisions between lead nuclei at the LHC that travel at almost the speed of light, it creates this quark–gluon plasma, a hot and dense state of matter that is believed to have filled the universe right after the Big Bang took place. There’s also a strong electromagnetic field emanating from lead nuclei.
It turns out that high-speed lead nuclei, the frequent near-miss interactions between them, and their electromagnetic field are a recipe for gold. “… the very high speed at which lead nuclei travel in the LHC (corresponding to 99.999993% of the speed of light) causes the electromagnetic field lines to be squashed into a thin pancake, transverse to the direction of motion, producing a short-lived pulse of photons,” explained the folks at CERN (European Organization for Nuclear Research), which runs the LHC.
“Often, this triggers a process called electromagnetic dissociation, whereby a photon interacting with a nucleus can excite oscillations of its internal structure, resulting in the ejection of small numbers of neutrons and protons. To create gold (a nucleus containing 79 protons), three protons must be removed from a lead nucleus in the LHC beams. The ALICE team used the detector’s zero degree calorimeters (ZDC) to count the number of photon–nucleus interactions that resulted in the emission of zero, one, two and three protons accompanied by at least one neutron, which are associated with the production of lead, thallium, mercury and gold, respectively.”
As such, gold nuclei emerged from the collision and hit the LHC beam pipe, where they immediately fragmented into single protons, neutrons and other particles. So effectively, lead transmutated into gold in the experimental setup through near-miss collisions, for the briefest of moments.
This is the first time gold production has been measured at the LHC, and the results appeared in Physical Review Journals last week. Sure, it might only have been 29 picograms of gold, but it still technically counts as alchemy. Our ancestors may indeed have been onto something all those hundreds of years ago after all.
Source: CERN