Double magic discovery

The deformed nucleus of zirconium-80 is lighter than the sum of the masses of 40 protons and 40 neutrons. The lost mass is converted to binding energy via E = mc2. The binding energy plays a role in bringing the nuclei together.Credit: Rare isotope beam facility

A team of researchers, including scientists from the National Institute for Superconducting Cyclotrons (NSCL) and Michigan State University (MSU) Rare Isotope Beam Facility (FRIB), has resolved a case of lack of mass of zirconium-80. ..

To be fair, they also broke the case.The experimenter has found that zirconium-80-a zirconium atom with 40 protons and 40 neutrons in its core or Nuclear— Lighter than expected by using NSCL’s unparalleled capabilities to create rare isotopes and analyze them.Then FRIB theorists could use advanced to explain its missing parts. Nuclear model And new statistical methods.

“The interaction between nuclear theorists and experimenters is like a coordinated dance,” said FRIB’s graduate research assistant and lead author of a study published in the journal on November 25 by the team. Alec Hamaker says. Nature Physics. “Each takes turns leading and following the other.”

“Theory may make predictions in advance, or experiments may reveal unexpected things,” said Ryan Ringle, senior scientist at the FRIB Institute, who belonged to the group that made the zirconium-80. Says. mass measurement. Ringle is also a part-time associate professor of physics at FRIB and a department of physics and astronomy at MSU’s University of Natural Sciences.

“They push each other, which basically brings a better understanding of the core that makes up everything we interact with,” he said.

Therefore, this story is bigger than one core. In a sense, this is a preview of the power of FRIB, a nuclear science user facility supported by the Nuclear Physics Department of the US Department of Energy Science.

As user manipulation begins next year, nuclear scientists around the world will have the opportunity to use FRIB’s technology to create rare isotopes that cannot be studied elsewhere. You will also have the opportunity to work with FRIB experts to understand the results of these studies and their implications. That knowledge has a wide range of applications, from helping scientists better understand the universe to improving cancer treatment.

“As we move into the FRIB era, we can make measurements like those we did here,” says Ringle. “We can go even further. We have enough capacity here to continue learning for decades.”

That said, Zirconium-80 is a really interesting core in itself.

To get started, it’s a difficult nucleus to make, but making a rare nucleus is NSCL’s specialty. The facility produced enough zirconium-80 to allow Ringle, Hamaker, and their colleagues to determine their mass with unprecedented accuracy. To do this, they used what is known as a Penning Trap mass spectrometer at NSCL’s low-energy beam and ion trap (LEBIT) facilities.

“People have measured this mass before, but never accurately,” Hamaker said. “And it revealed some interesting physics.”

“When we make mass measurements at this accurate level, we are actually measuring the amount of mass that is missing,” Ringle said. “The mass of nuclei is not just the sum of the masses of protons and neutrons. There is a shortage of mass that appears as the energy that holds the nuclei together.”

This is where one of the most famous equations in science helps explain things. Albert Einstein’s E = mc2, E stands for energy and m stands for mass (c is the symbol of the speed of light). This means that the mass and energy are equivalent, but this is only noticeable in the extreme conditions found in the core of an atom.

When the nucleus has more binding energy, that is, it holds more protons and neutrons, it will have more. Missing mass.. It helps explain the situation of Zirconium-80. The nuclei are tightly bound, and this new measurement reveals that the binding is even stronger than expected.

This meant that FRIB theorists had to find an explanation and could rely on predictions decades ago to provide an answer. For example, theorists suspected that the zirconium-80 nucleus could be magical.

Sometimes a particular nucleus goes against its mass expectations by having a special number of protons or neutrons. Physicists call these magic numbers. Theoretically, zirconium-80 has a special number of protons and neutrons, which makes it doubly magical.

Previous experiments have shown that zirconium-80 is more like a rugby ball or American football than a ball. Theorists have predicted that shape can cause this double magic. The most accurate measurement of the mass of zirconium-80 to date has allowed scientists to support these ideas with solid data.

“Theorists predicted that zirconium-80 was a double-magic nucleus that was deformed over 30 years ago,” Hamaker said. “It took some time for the experimenter to learn the dance and provide evidence to the theorist. The evidence is there so that the theorist can perform the next few steps of the dance. “

So, to continue dancing and extend the metaphor, NSCL, FRIB, and MSU offer one of the best ballrooms to do it. We are proud of our unique facilities, professional staff, and top-class nuclear physics graduate program in Japan.

“I can work in the field at national user facilities on topics at the forefront of nuclear science,” says Hamaker. “This experience has helped me build relationships and learn from many of the lab’s staff and researchers. The science of the lab and its dedication to world-leading facilities and equipment have made the project a success. bottom.”

Learn what tickles the nucleus

For more information:
Alec Hamaker, precision mass measurement of lightweight self-conjugated nucleus 80Zr, Nature Physics (2021). DOI: 10.1038 / s41567-021-01395-w..

Quote: Double Magic Discovery (November 25, 2021) Obtained November 25, 2021 from https: //

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