B FRIB creates five new isotopes (Tm-182,-183; Yb-186,-187; Lu-190)

[Astronuc]

In creating five new isotopes, an international research team working at the Facility for Rare Isotope Beams, or FRIB, at Michigan State University has brought the stars closer to Earth.

The isotopes — known as thulium-182, thulium-183, ytterbium-186, ytterbium-187 and lutetium-190 — were reported 15 February in the journal Physical Review Letters.

These represent the first batch of new isotopes made at FRIB, a user facility for the U.S. Department of Energy Office of Science (DOE-SC), supporting the mission of the DOE-SC Office of Nuclear Physics. The new isotopes show that FRIB is nearing the creation of nuclear specimens that currently only exist when ultradense celestial bodies known as neutron stars crash into each other.

https://frib.msu.edu/news/2024/new-isotopes

Physcial Review Letters
https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.132.072501

¹⁹⁸Pt atoms of 186 MeV/u were directed onto a carbon target; primary beam power was 1.5 kW.

https://frib.msu.edu/

 

[Astronuc]

Putting the reactions in perspective, one takes ¹⁹⁸Pt + ¹²C for a total of 210 nucleons and knock it down to 182, 183, 186, 187 and 190, through spallation reactions, or as some call it, nuclear fragmentation, or heavy-ion fragentation (the nuclei get fragmented).

Pt has Z = 78 and one produces Tm (Z=69), Yb (Z=70) and Lu (Z=71), so knocking out 9, 8, and 7 protons from the Pt nucleus with a number or neutrons.

The reported nuclides are not yet in the Table of Nuclides, and the nearest neighbors have very short half-lives of > 160 ns, and ostensibly in the μs range, or less than 1 μs.

The way the media portray the experimental work
https://www.sciencealert.com/physicists-discover-brand-new-isotopes-of-heavy-rare-earth-elements
https://www.scientificamerican.com/article/weird-lab-made-atoms-hint-at-heavy-metals-cosmic-origins/
https://phys.org/news/2024-02-nuclei-fundamental-science-earth-cosmos.html

I'm going to read the PRL article.

 

[DaveE]

OK, beyond the idea that discovery is good, because we may be surprised, can someone explain in layman's terms why we care?

I'm not criticizing, I don't know enough to do that. It's genuine curiosity. Who was waiting for this data? Why was this a funding priority compared to other DOE stuff?

 

[Vanadium 50]

Is your question "why is there FRIB?", "why are new isotopes interesting?" or "how are we going to make money off this?"

 

[DaveE]

These:

"why is there FRIB?", "why are new isotopes interesting?"

 

[Astronuc]

OK, beyond the idea that discovery is good, because we may be surprised, can someone explain in layman's terms why we care?

I'm not criticizing, I don't know enough to do that. It's genuine curiosity. Who was waiting for this data? Why was this a funding priority compared to other DOE stuff?

All good questions. The National Science Foundation (NSF) and US DOE Office of Science provided funding (they are sponsors). The information is distributed to a variety of interested parties.

Previous work produced ¹⁹²Hf, ¹⁹¹Hf, and ¹⁸⁹Lu using ¹⁹⁸Pt⁶¹⁺ into a Be target with energy of 85 MeV/u. "A novel approach was developed to measure cross sections when working with multiple charge states of high-Z fragments." The experiment used the Coupled Cyclotron Facility (CCF) at the NSF’s National Superconducting Cyclotron Laboratory (NSCL) at MSU.

https://nscl.msu.edu/public/tour/NSCL Brochure 2015.pdf

FRIB uses a linear accelerator.

The latest experiment (see the OP) used an ion energy of 186 MeV/u, and there are plans to go to even high energy. The Pt ions had charges of 66+, 67+ and 68+. The beam "was accelerated through the three segments of the FRIB linear accelerator."

The experiments provide data to compare with theory, e.g., cross-section models, and apparently, some motivation is to elucidate possible reactions in the r-process in stellar nucleosynthesis.

Aside from that, various articles indicate that there is no practical use for such isotopes, since they decay very rapidly.

In the summary of the recently reported work, the results yielded "the discovery of five previously unobserved neutron-rich nuclides in a region that approaches the r-process path. The experiment was the first new-isotope search carried out at the recently completed Facility for Rare Isotope Beams and already demonstrates the impressive capabilities and new science opportunities that are and will become available as the facility evolves toward its full beam intensity of 400 kW. It also indicates that neutron pickup reactions, leading to fragments with more neutrons than the primary beam, occur in the
intermediate energy regime and have the prospect to reach further into the unknown.

The unique capabilities of FRIB, including very intense primary beams at energies exceeding those that were available at NSCL, make it an ideal facility for exploring the region around neutron number N ¼ 126 and beyond. Researchers at FRIB can utilize these reactions to produce, identify, and study the properties of new isotopes, contributing to advancements in nuclear physics, astrophysics, and our understanding of the fundamental properties of matter."

Edit/update: I forgot to post the link
https://frib.msu.edu/users/beams

 

[Vanadium 50]

I'd argue as follows: the nuclear force is complicated, and has multiple pieces to it. There are about 250 stable nuclei, 350 naturally occurring ones, and over 1000 artificial ones. That's it. That's all the data we have.

All the viable models match the data we have. That's what viable means. If we want to distinguish between them, we need more data. FRIB can provide this data, and it provides it at the extremes of isospin. That more cleanly separates the parts of the force that depend on isospin from the parts that don't.

MSU has a history of doing this, but with light nuclei. FRIB allows this to be extended to middle-weight nuclei as well.

 

[billtodd]

I'd argue as follows: the nuclear force is complicated, and has multiple pieces to it. There are about 250 stable nuclei, 350 naturally occurring ones, and over 1000 artificial ones. That's it. That's all the data we have.

All the viable models match the data we have. That's what viable means. If we want to distinguish between them, we need more data. FRIB can provide this data, and it provides it at the extremes of isospin. That more cleanly separates the parts of the force that depend on isospin from the parts that don't.

MSU has a history of doing this, but with light nuclei. FRIB allows this to be extended to middle-weight nuclei as well.

Is there a limit on how much artificial ones can be formed?

 

[Vanadium 50]

Probably.

 

[billtodd]

Probably.

My attempt in writing a thesis in maths shows me that the limit might not even exist.
Here it's either finite or infinite, but you never really can tell if there are no more isotopes to discover.

 

[Astronuc]

Is there a limit on how much artificial ones can be formed?

As V50 indicated - probably - but we don't yet know that limit. None of the radionuclides/radisotopes beyond ²⁵²Cf have practical uses, (and practical uses are limited) and the elements heavier than U have with long-lived half-lives are few. Some notable nuclides are ²⁴⁴Pu and ²⁴⁷Cm.

https://orau.org/health-physics-museum/collection/radioactive-sources/californium-252-sources.html

Attempts are being considered to create isotopes of elements 119 and 120, and apparently attempts have been made, although it is not clear if those efforts are ongoing.

https://en.wikipedia.org/wiki/Ununennium Z=119
https://en.wikipedia.org/wiki/Unbinilium Z= 120

https://en.wikipedia.org/wiki/Oganesson

Oganesson has the highest atomic number and highest atomic mass of all known elements as of 2024. On the periodic table of the elements it is a p-block element, a member of group 18 and the last member of period 7. Its only known isotope, oganesson-294, is highly radioactive, with a half-life of 0.7 ms and, as of 2020, only five atoms have been successfully produced.

Not very practical to have only 5 atoms, let a long 1000, or 1 M atoms. Note that ²⁹⁴Og has Z=118, N=176 for A = 294, and the half-life is ~ 0.7 ms.

Special remote handling is required for such radionuclides as they tend to under spontaneous fission, so they must be shielded. Shielding is also required for the gamma and beta radiation, which would also block alpha particles.

As for what may come next, besides Z=119, 120, possibly a nuclide with 'magic numbers' of protons and neutrons, e.g., Z = 122 and 124, with N = 184, so A = 306 and 308, respectively.
https://en.wikipedia.org/wiki/Magic_number_(physics)
https://en.wikipedia.org/wiki/Island_of_stability