New Measurements of Double Magic Atom Reveal Surprise
An experiment involving the collision of specialized lead atoms with high-speed particles has revealed an astonishing finding.
Rather than the expected perfect spherical shape, the core of the isotope known as lead-208 (208Pb) appears unexpectedly flattened.
The Surprising Results of the Experiment on Lead-208
This discovery indicates that atomic nuclei might be more intricate than previously thought and could have significant implications for our understanding of the formation of heavy elements.
The researchers explain in their paper, “These results suggest a time-averaged prolate deformation for the system. Even though 208Pb is a key element in nuclear physics, it remains an enigma for nuclear structure theories.”
208Pb is considered a unique atom. When the number of protons or neutrons in an atom is a “magic” number, the nucleons form a completely filled shell. An atom with both its protons and neutrons having magic numbers is referred to as doubly magic; 208Pb is one such atom, containing 82 protons and 126 neutrons.
Doubly magic nuclei are particularly stable against nuclear decay, and 208Pb is the heaviest known stable isotope of any element. As a result, it is a cornerstone of nuclear physics and crucial to understanding doubly magic nuclei in general.
Due to its remarkable stability, scientists initially believed the nucleus must be perfectly spherical. However, when they used the GRETINA gamma-ray spectrometer at the Argonne National Laboratory in the US to investigate its structure, they discovered something unexpected.
Revealing Lead-208’s Shape with Cutting-Edge Technology
“We managed to combine four separate measurements using the most advanced equipment in the world for this type of study, which allowed us to make this groundbreaking observation,” Henderson explains.
“The result surprised us, showing definitively that lead-208 is not spherical, as one might have assumed. Our findings directly challenge previous nuclear theory results, offering a promising avenue for future research.”
The experiments involved bombarding the 208Pb nuclei with particles accelerated to a staggering 10 percent of the speed of light – approximately 30,000 kilometers (19,000 miles) per second. This high-speed bombardment excites quantum states in the nucleus, enabling physicists to analyze these states to reveal the nucleus’s shape.
By taking four separate measurements of the quantum states, the researchers discovered the slightly flattened shape of the 208Pb nucleus.
Although 208Pb had been extensively studied, finding that its shape differs from earlier assumptions is a surprising revelation. The researchers admit they are unsure why it has this oblate spheroid shape.
This finding suggests there is more complexity within atomic nuclei than previously believed, and additional research is needed to fully understand their behavior.
“These highly sensitive experiments have provided new insights into something we thought we understood well, posing the new challenge of understanding why this occurs,” says nuclear physicist Paul Stevenson of the University of Surrey.
One possibility is that the vibrations of the 208Pb nucleus, when excited during the experiments, may be less regular than we had previously assumed. We are now refining our theories to determine if these ideas are correct.
Read the original article on: Science Alert
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