Physicists Build New Mendelevium Isotopes

Physicists build new Mendelevium isotopes

Physicists build new Mendelevium isotopes. In an experiment conducted on the 88-inch cyclotron at the Lawrence Berkeley National Laboratory, a team of physicists successfully created a new isotope of the artificial element Mendelium. Mendelevium, a synthetic radioactive element in the actinide family with the symbol Md and atomic number 10, was first created in 1955 by scientists at the Berkeley Laboratory.

The newly formed isotope, Mendelium-244, is the 17th and lightest form of Mendeleevium. "Division of Nuclear Sciences in Scientists at Lawrence Berkeley National Laboratory" Team Leaders Drs. Jennifer Por said: "It was a challenge to find this new Mendelium isotope, because all neighboring Mendelium isotopes have very similar decomposition properties."

In general, Drs. Porre and her colleagues measured the properties of 10 atoms of Mendeleevium-244. They found evidence that the new isotopes have two different decay series, each of which leads to a different half-life: 0.4 seconds and 6 seconds, depending on the different energy settings of the particles in their nucleus. The 88-inch central cyclotron for the Mendelium-244 discovery contained a device known as Fiona (to identify nuclide A).

"The most important tool we had in this discovery was Fiona," said Dr. Por said. The team used Fiona to accurately measure the mass number of Mendelium-244. Director of the Nuclear Science Division of the Lawrence Berkeley National Laboratory, Drs. Barbara Jacque said: "We built Fiona to allow for such discoveries, and it is exciting to see this tool in its progress."

"The discovery of isotopes is cyclical and relies heavily on the development of new accelerators and experimental equipment," said Professor Michael Thonensen of Michigan State University. To ensure that Fiona's measurements were correct, the researchers first measured the decomposition properties and mass numbers of known Mendelivium isotopes, including Mendeleevium-247, Mendeleevium-246, and Mendelium-244.

"When we realized that we were well aware of the properties of these mild Mendelium isotopes, we attempted an experiment to discover the previously useless Mendelium-244 isotope," said Dr. Por explained. "Without direct confirmation that we produced an isotope with a high number of 244, it would have been very difficult to separate the results and test the finding."

In addition to the discovery of Mendeleevium-244, scientists found the first evidence of the alpha decomposition process of beryllium-236, a isotope of beryllium, as it converts to americium-232, a slightly lighter isotope. Their results were published in the journal Physical Review Letters.

We present a new isotope

We present a new isotope: Mendelium-244. Jennifer Por, a Berkeley Lab project scientist who expanded the Mendelium-244 search to lead the study, operates a Berkeley gas-filled separator vacuum controller on the Berkeley Lab 88-inch cyclotron in this 2018 photo. Credit: By Lawrence Lawrence Jr., Lawrence Berkeley National Laboratory.

A team of scientists working at the Lawrence Berkeley National Laboratory (Berkeley Lab) discovered a new form of the man-made element Mendelium. The newly formed isotope, Mendelium-244, is the 17th and lightest form of Mendeleevium, element 101 on the periodic table.

Mendeleevium was first created by Berkeley Lab scientists in 1955 (see related video), and is included in a list of 16 other elements that Berkeley Lab scientists discovered or helped discover. An isotope is a form of an element that has more or fewer neutrons (unchanged particles) in its atomic nucleus than other forms of an element.

In the latest discovery, the team used the Berkeley Lab's 88-inch cyclotron, which accelerates powerful target particle beams, to form heavier element atoms, to form Mendeleevium-244. A cyclotron is a type of particle accelerator invented by the name of the laboratory, Ernest O. Lawrence made it in 1930.

Teams led by Berkeley Lab have uncovered 12 of Mendeleevium's 17 isotopes, and a total of 640 isotopes with almost fifth of all known isotopes and by far the highest count for a single institution. There were 3,308 isotopes known at the end of 2019. The new isotope discovery is the first since 2010 by a team led by Berkeley Lab.

"It was challenging to find this new Mendeleevium isotope because all of the neighboring Mendelium isotopes have very similar decomposition properties," said Jennifer Por, a scientist at the Berkeley Laboratory who studied the discovery of isotopes. Alpha decay describes the process by which a radioactive element breaks down into lighter elements over time.

Overall, the team measured the properties of 10 atoms of Mendelium-244 for the study, which appeared today in the Journal of Physical Review Letters. Each isotope represents a unique combination of protons and neutrons, said Pore. When a new isotope is discovered, that particular combination of protons (positively charged particles) and neutrons has never been observed.

Studying these extreme combinations is critical to our understanding of all atomic matter. The Fiona instrument was instrumental in confirming the discovery of Mendeleevium-244 in the Berkeley Lab 88-inch cyclotron. In addition to the discovery of new isotopes, the research team's work also provided the first direct evidence of a decomposition process involving a isotope of the element barkelium.

The team included scientists from the University of California, Berkeley, Lawrence Livermore National Laboratory, San Jose State University, and Lund University, Sweden. The researchers found evidence that Mendelium-244 has two distinct series of decays.

Each of which leads to a different half-life: 0.4 seconds and 6 seconds, depending on the different energy configurations of the particles in their nucleus. A half-life is to halve the number of atoms of a radioactive element as its nuclei decay to other lighter nuclei.

In a separate measurement derived from the same study, the researchers found the first evidence of the alpha decomposition process of beryllium-236, an isotope of the element beryllium, which converts to americium-232, a slightly lighter isotope. Berkelium was discovered in 1949 by a team led by Berkeley Lab.

A central element of the isotope discovery was a device in the 88-inch cyclotron called Fiona, or "F" in Fiona, to identify nucleoid A, which represents the mass number of an element, the total number of protons (positive form ). Charged particles) and neutrons (unchanged particles) in the nucleus of an atom. The mass number of the new isotope is 244.

"The most important tool we had in this search was Fiona," said Por, who was also part of the Fiona team that assisted with testing and commissioning. Fiona accurately measured the mass of the new isotope. "We built Fiona to enable such discoveries, and it is exciting to see this tool outperforming our progress," said Barbara Jacque, director of the Division of Nuclear Science at Berkeley Lab.

Michael Thonensen, a distinguished professor at the University of Michigan State University who is on leave to serve as editor-in-chief of the American Physical Society, maintains a list of isotope discoveries and notes that the list of new slim isotopes for the past few days. Years.

Construction of Mendeleevium-244: In this video, Berkeley Lab project scientist Jennifer Porr describes how scientists working on the 88-inch Berkeley Lab cyclotron confirmed and created the discovery of a new isotope, Mendelium-244. Mendeleevium, an artificial element, was first discovered by the Berkeley Lab team in 1955, and since then more than a dozen variants of this element, known as isotopes, have been discovered.

"The isotope discoveries are cyclical and depend on new accelerators and breakthroughs in the development of experimental equipment," he said. She claimed that Fiona and the Berkeley Lab, US Department of Energy, Rare Isotopic Ray Facility (FRIB). USA In Development from Michigan State University, USA USA It has unique "highly searchable" capabilities for a variety of new isotopes.

To ensure that Fiona's measurements were correct, the research team first measured the decomposition properties and mass numbers of known Mendeleevium isotopes, including Mendeleevium-247, Mendeleevium-246, and Mendelium-245. "Once we were convinced that we knew the properties of these mild Mendelium isotopes well, we attempted an experiment to find the previously useless Mendelium-244 isotope," Por said.

"Without direct confirmation that we produced an isotope with a high number of 244, it would have been very difficult to separate the results and test the finding." To create these exotic isotopes, even the lightest known form of Mendeleevium is naturally heavier than uranium, scientists produced a particle beam in an 88-inch cyclotron, with particles charged with argon-40.

An isotope of argon, and directed at lightning. A thin-film target made of bismuth-209 is an isotope of bismuth. Sometimes, in these experiments, a nucleus in a beam of high-energy particles directly collides with a nucleus in the target plate and fuses together, producing an atom of a heavier element.

And for an isotope with a very short half-life, it's a race to take measurements of an atom before it fades away into something else. Fiona has another device on Berkeley's 88-inch cyclotron, called the Berkeley Gas-Filled Separator. The separator helps eject relevant atoms that can be measured in detail and individually with Fiona.

The researchers may follow other studies of Mendeleevium-244 to try to learn more about its structure, Por said, and that Fiona has now proven its worth in discovering isotopes, Berkeley Lab. Researchers are setting their sights on other new isotopes. "We are already planning studies similar to other isotope chains to discover new isotopes," said Por.