Brookhaven’s oxygen collisions show 20% jet-energy suppression
The STAR experiment at Brookhaven’s Relativistic Heavy Ion Collider found a 20% suppression of high-energy particles in oxygen collisions recorded in 2021, a signal of jet quenching. Brookhaven says the result is strong evidence that these small collisions formed quark-gluon plasma, though physicists are still investigating the minimum conditions needed to create it.
Bottom line — The Large Hadron Collider’s higher-energy oxygen data offer a comparison; Brookhaven researchers expect its quenching signal to be stronger.
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Brookhaven says the collisions took place at 200 billion electron volts, below the LHC’s oxygen-collision energy of more than 5,000 billion electron volts.
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The suppression was weaker than in RHIC’s gold collisions, consistent with a smaller plasma system, according to Brookhaven.
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The team compared head-on oxygen collisions with glancing collisions, which are not expected to produce plasma.
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Oxygen nuclei contain 8 protons and 8 neutrons; the nuclei are spherical, Brookhaven says.
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The result was published in Physical Review Letters.