Physicists temporarily create gold from lead using high-speed collisions

Physicists at CERN briefly turned lead into gold using high-speed collisions at near-light speeds at the Large Hadron Collider.

: CERN researchers achieved a long-held alchemical dream by creating gold from lead, albeit fleetingly and in tiny amounts, using the Large Hadron Collider. They utilized near-miss collisions of lead nuclei traveling at 99.999993% of the speed of light to harness intense electromagnetic fields that trigger rare nuclear transformations. The process only produced approximately 86 billion gold nuclei during the LHC's Run 2 (2015-2018), resulting in a mass of 29 picograms. While the amount of gold created is minute, the experiment significantly advances understanding of nuclear physics and refines models crucial for particle beam management.

The desire to transform lead into gold has been a fascination stretching back to ancient alchemy, with alchemists viewing gold as the ultimate material due to its beauty and resistance to corrosion. Although chemically impossible, nuclear physics at CERN's Large Hadron Collider (LHC) has allowed researchers to achieve this ambition momentarily. This cutting-edge research was documented by the ALICE collaboration and published in Physical Review Journals, describing how high-energy physics can create gold from lead under specific conditions.

At the heart of this breakthrough is the use of high-speed collisions where lead nuclei are propelled to 99.999993% of the speed of light. Instead of crashing head-on, these nuclei pass close enough to initiate electromagnetic interactions that result in rare nuclear transformations. The key process, known as electromagnetic dissociation, occurs when photons in the electromagnetic field of a lead nucleus, compressed due to the high velocities, collide with nearby nuclei, leading to the ejection of protons and neutrons.

Through these interactions at the LHC, researchers used zero degree calorimeters to precisely detect and measure the outcomes of the near-miss collisions. This allowed them to distinguish various nuclear reactions: no protons lost results in remaining lead, whereas the loss of one, two, or three protons transforms the original lead atoms into thallium, mercury, or gold respectively. Though the technical accomplishment of creating gold is impressive, the amount produced was only about 29 picograms during Run 2 of LHC (2015-2018), and even with recent upgrades, these results remain minuscule compared to commercial quantities.

Despite the minimal amount of gold produced, this experiment is significant for nuclear physics. It refines the current understanding of electromagnetic dissociation, which plays a crucial role in controlling and enhancing the efficiency of particle beams not only in the LHC but in future particle colliders. John Jowett from the ALICE collaboration highlighted the importance of understanding beam losses, which can be a major factor limiting collider performance.

Marco Van Leeuwen, another ALICE spokesperson, remarked on the dual capability of their detectors to manage both complex and minimal particle collisions. The knowledge gained from these experiments not only feeds into the better control of particle accelerators but also contributes to scientific knowledge about fundamental forces that originated from the universe's earliest moments, helping to understand processes that were only theory until now.

Sources: TechSpot, Physical Review Journals

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