Vanderbilt physics professors Dr. Joseph Hamilton and Dr. A.V. Ramayya were a critical part of a team of American and Russian scientists that discovered an element that fills in the last remaining blank on the periodic table.
Element 117, which was created by smashing together calcium-48 and berkelium in a particle accelerator in Dubna, Russia, is a stepping stone towards the discovery of more massive elements, which have the potential to depart from expected chemical behavior and to unlock new theories about nuclear structure.
“Our 117 discovery is very important in developing and verifying our theoretical understandings of how elements are formed in nature and the behavior of nuclear matter in the nucleus under extreme conditions,” said Hamilton.
Hamilton and Ramayaa went to Russia on several occasions for experiments and continuously monitored the results via the Internet. The radioactive berkelium was created in a high neutron flux reactor laboratory in Oak Ridge, TN.
Element 117 gives evidence that a theorized “island of stability” may exist as new elements continue to get heavier by adding more neutrons.
“The predictions are that if you could get an element with 184 neutrons, it would be a spherical, magical number that would give great stability to a nucleus, so much that it could be long lived enough to perhaps exist in nature,” Hamilton said.
With 177 neutrons, element 117 is the closest anyone has come to this number, and its lifetime is the longest of any of the superheavy elements.
“Its half-life is 100 times longer than element 112 or 118,” Hamilton said. “Our experiments do confirm that 184 neutrons has some special stability because all of the isotopes we have seen during radioactive decay of element 117 have longer lifetimes than others.”
Hamilton’s inception and funding of the project gives him the honor naming the element.
“The rule is the person who is the first author on the paper gets to choose the name,” Hamilton said, “but before they did the experiment they agreed that I could name it because of my work to get the group together and to get the berkelium.
A name has been selected, but they are waiting until they receive confirmation from the International Union of Pure and Applied Chemistry to release it.
“IUPAC reads papers and looks for corroborating evidence to justify that our claim is correct,” Hamilton said. “They have already accepted this reaction technique to identify elements 114 and 116, so we expect they will be able to accept our papers.”
In the meantime, the group is planning future experiments to look for elements 119 and 120 along with heavier isotopes of elements 117 and 118. The ultimate goal is to find the “island of stability” where elements can exist long enough to test their chemical and physical properties.