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A 3D illustration of a neutron star in a gas nebula.
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Physicists have measured the microscopically thin skin of neutrons enclosing the insides of atoms of lead for the first time, finding that it s thicker than expected. The discovery could help to unravel some of the mysteries of neutron stars ultradense stellar corpses that are chock full of neutrons.
An atom s skin is an odd thing to imagine. The popular image of the atomic nucleus tends to depict protons and neutrons being packed together randomly inside a sphere like gumballs in an old-fashioned glass dispenser. But in reality, heavier elements tend to distribute their building blocks more unevenly, with some neutrons nudged outward to form a thin skin that encloses the core of mixed neutrons and protons.
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Physicists have measured the “skin” of an atom for the first time and, perhaps unsurprisingly, it is extremely thin. The measurement may help us understand the properties of neutron stars.
Lead-208, an isotope that contains 82 protons and 126 neutrons, has a type of nucleus that physicists refer to as “doubly magic” because both the protons and the neutrons are arranged neatly into shells inside the nucleus. These shells keep the atom relatively stable and make it simpler to experiment on, so when the PREX collaboration at the Thomas Jefferson National Accelerator Facility in Virginia set out to measure neutron skin, they opted to experiment on lead-208.
Measuring lead nucleus tells of neutron stars cosmosmagazine.com - get the latest breaking news, showbiz & celebrity photos, sport news & rumours, viral videos and top stories from cosmosmagazine.com Daily Mail and Mail on Sunday newspapers.
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IMAGE: Jefferson Lab s Experimental Hall A is one of four nuclear physics research areas in the lab s Continuous Electron Beam Accelerator Facility. view more
Credit: DOE s Jefferson Lab
NEWPORT NEWS - Nuclear physicists have made a new, highly accurate measurement of the thickness of the neutron skin that encompasses the lead nucleus in experiments conducted at the U.S. Department of Energy s Thomas Jefferson National Accelerator Facility and just published in Physical Review Letters. The result, which revealed a neutron skin thickness of .28 millionths of a nanometer, has important implications for the structure and size of neutron stars.
The protons and neutrons that form the nucleus at the heart of every atom in the universe help determine each atom s identity and properties. Nuclear physicists are studying different nuclei to learn more about how these protons and neutrons act inside the nucleus. The Lead Radius Experiment collaboration, called PREx (af