A long-held belief about one of the universe’s heaviest stable isotopes has been upended by new findings that challenge past beliefs that its atomic nucleus is perfectly spherical.
The discovery, made by an international collaboration led by researchers with the University of Surrey’s Nuclear Physics Group, is now causing scientists to rethink some of their longstanding assumptions about the heaviest elements in our universe and how they are formed.
Lead is the element with the heaviest, most highly stable isotope, Lead-208 (²⁰⁸Pb). This isotope possesses a doubly magic nucleus—essentially an atomic nucleus that has a “magic” number of both protons and neutrons—meaning it is extremely stable.
In their research, the international team reexamined Lead-208’s shape with a new experimental probe, which revealed something unexpected: rather than the perfectly spherical shape the team expected to see, the isotope’s nucleus is more akin to an elongated oval shape, not unlike a football.
“We were able to combine four separate measurements using the world’s most sensitive experimental equipment for this type of study, which is what allowed us to make this challenging observation,” said Dr. Jack Henderson, the study’s principal investigator and a researcher from the University of Surrey’s School of Mathematics and Physics.
“What we saw surprised us,” Henderson said, “demonstrating conclusively that lead-208 is not spherical, as one might naively assume.”
“The findings directly challenge results from our colleagues in nuclear theory, presenting an exciting avenue for future research,” Henderson said.
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