Nav: Home

Researchers examine puzzling sizes of extremely light calcium isotopes

February 11, 2019

Michigan State University researchers have measured for the first time the nuclei of three protein-rich calcium isotopes, according to a new paper published in Nature Physics.

One of the most fundamental properties of the nucleus is its size. The nuclear radius generally increases with the number of proton and neutron constituents. However, when examined closely, the radii vary in unique ways, reflecting the intricate behavior of protons and neutrons inside the nucleus.

Of particular interest is the variation of the charge radii of calcium isotopes. They exhibit a peculiar behavior with calcium-48 having almost the same radius as calcium-40, a local maximum at calcium-44, a distinct odd-even zigzag pattern, and a very large radius for calcium-52. Although the pattern has been partially explained (gray line in the figure), many existing theories struggle to explain this behavior. Below the lightest stable calcium-40 isotope, the charge radius has been known only for calcium-39, due to the difficulty in producing proton-rich calcium nuclei.

The radius of a calcium nucleus is small, about 0.0000000000000035 meters (or 3.5 femtometers), and the local variation is 200 times smaller still. Moreover, the proton-rich calcium isotopes are rather short-lived. For example, calcium-36 exists for just one tenth of a second. The tiny changes in charge radii of very short-lived isotopes can be measured using the laser spectroscopy technique developed at the BEam COoler and LAser spectroscopy, BECOLA, facility at the National Superconducting Cyclotron Laboratory at Michigan State University.

The research, led by Andrew Miller, NSCL graduate assistant, measured for the first time (red squares in figure) the charge radii of three proton-rich calcium isotopes (with mass numbers A=36, 37, 38). These were found to be much smaller than previous theoretical predictions and present a new puzzle. However, an improved theoretical model with a focus on these present data remarkably reproduces the general trend of radii from calcium-36 all the way to calcium-52 (blue line in figure). This success can be attributed to a better understanding of the peculiar ways in which protons interact with each other at large distances outside the surface of a proton-rich calcium nucleus. The improved understanding of charge radii will impact further developments of a global model of the atomic nucleus.

The laser spectroscopy experiment at BECOLA and the improved nuclear model will play an even more essential role in the determination and interpretation of radii of nuclei at the Facility for Rare Isotope Beams currently under construction at MSU, which will provide unprecedented access to new rare isotopes.
-end-
(Editor's note: Please include a link to the original paper in online coverage: https://www.nature.com/articles/s41567-019-0416-9

Michigan State University

Related Calcium Articles:

Chelated calcium benefits poinsettias
Cutting quality has an impact on postharvest durability during shipping and propagation of poinsettias.
New study uncovers the interaction of calcium channels
Korean researchers have identified the interactions of the combinants among calcium channel proteins that exist in nerve and heart cells.
Calcium-catalyzed reactions of element-H bonds
Calcium-catalyzed reactions of element-H bonds provide precise and efficient tools for hydrofunctionalization.
Memory molecule limits plasticity by calibrating calcium
Researchers at the Max Planck Florida Institute for Neuroscience in collaboration with researchers at Emory University and the National Institute of Environmental Health Sciences, have for the first time identified a novel role for the CA2-enriched protein RGS14 and provided insights into the mechanism by which it limits plasticity.
A bioengineered tattoo monitors blood calcium levels
Scientists have created a biomedical tattoo that becomes visible on the skin of mice in response to elevated levels of calcium in the blood.
More Calcium News and Calcium Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Erasing The Stigma
Many of us either cope with mental illness or know someone who does. But we still have a hard time talking about it. This hour, TED speakers explore ways to push past — and even erase — the stigma. Guests include musician and comedian Jordan Raskopoulos, neuroscientist and psychiatrist Thomas Insel, psychiatrist Dixon Chibanda, anxiety and depression researcher Olivia Remes, and entrepreneur Sangu Delle.
Now Playing: Science for the People

#537 Science Journalism, Hold the Hype
Everyone's seen a piece of science getting over-exaggerated in the media. Most people would be quick to blame journalists and big media for getting in wrong. In many cases, you'd be right. But there's other sources of hype in science journalism. and one of them can be found in the humble, and little-known press release. We're talking with Chris Chambers about doing science about science journalism, and where the hype creeps in. Related links: The association between exaggeration in health related science news and academic press releases: retrospective observational study Claims of causality in health news: a randomised trial This...