Friday, March 17, 2006

Michigan State University Newsroom - Physics discovery: Nuclei still full of surprises, say MSU scientists

EAST LANSING, Mich. — Scientists at the National Superconducting Cyclotron Laboratory at Michigan State University have reproduced the processes inside stars in a laboratory to produce one isotope – Copper 57 – that revealed a mystery in one of its subatomic cousins, Nickel 56.The work has been accepted for publication in Physical Review Letters.Paul Mantica, a professor at the laboratory who specializes in nuclear chemistry, explained that in the quest for physicists to understand how the nucleus behaves, its standard operating procedure is to take what’s known and make assumptions about what must be true about unknowns.That’s where Nickel 56 – known as Ni-56 for short – comes in.Mantica and Kei Minamisono, a research associate, used nuclear magnetic resonance – a more sensitive relative of the magnetic resonance imaging used in medicine – to peer into the inner workings of elements. The magnetic resonance method is aided by polarizing the Cu-57 nuclei (assuring that they all “point” in the same direction) using a technique pioneered at MSU’s cyclotron laboratory. A measure of the magnetic nature of Cu-57 would then provide details about Ni-56.Scientists had hypothesized that Ni-56 should look a certain way.Ni-56 is what scientists call “doubly-magic.” That means that its number of protons and number of neutrons are in a subatomically tidy package that makes it more stable and easier to study.It’s like studying a bunch of cats and dogs. The groups are a lot easier to keep track of if they’re in a pen. That, basically, is what being doubly magic is – an isotope with the protons and neutrons in defined pens. The 28 protons and neutrons are more stable, and less likely to fall apart, when they’re penned up.Because Cu-57 is a close relative, scientists were betting its core should also be all neat and tidy. But Mantica said the experiment showed otherwise.“We found that the core is broken,” Mantica said. “It looks like it’s more open, like the double magic core is broken apart. Instead of solid core, we have a bunch of loose protons and neutrons.”And thus more work for physicists to do.


No comments: