https://www.nature.com/articles/d41586-023-02713-3 Skip to main content Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript. Advertisement Advertisement Nature * View all journals * Search * Log in * Explore content * About the journal * Publish with us * Subscribe * Sign up for alerts * RSS feed 1. nature 2. news 3. article * NEWS * 30 August 2023 Rare oxygen isotope detected at last -- and it defies expectations Oxygen-28 might prompt physicists to revamp theories of how atomic nuclei are structured. * Katherine Bourzac 1. Katherine Bourzac View author publications You can also search for this author in PubMed Google Scholar * Twitter * Facebook * Email You have full access to this article via your institution. Download PDF The Superconducting Ring Cyclotron in the Radioactive Isotope Beam Factory in Wako, Saitama, Japan. The Riken RI Beam Factory in Wako, Japan, creates streams of radioactive isotopes with help from this superconducting ring cyclotron.Credit: Nishina Center for Accelerator-Based Science By combining a powerful set of instruments with some experimental savvy, physicists have for the first time detected oxygen-28 -- an isotope of oxygen that has 12 extra neutrons packed into its nucleus. Scientists have long predicted that this isotope is unusually stable. But initial observations of the ^28O nucleus suggest that this isn't the case: it disintegrates rapidly after creation, a team reports in Nature today^1. If the results can be replicated, physicists might need to update theories of how atomic nuclei are structured. [d41586-023] Long-awaited accelerator ready to explore origins of elements The strongest force in the Universe is the one that holds together the protons and neutrons in an atom's nucleus. To unlock how elements are forged, the physics of neutron stars and more, scientists need to better understand this strong nuclear force, says Takashi Nakamura, a physicist at the Tokyo Institute of Technology. He and other researchers are testing theories about how atomic nuclei are held together by pushing them to extremes. One popular way is to load lightweight nuclei, such as oxygen, with excess neutrons and see what happens. Current theories state that atomic nuclei with certain numbers of protons and neutrons are inherently stable. This is because protons and neutrons fill up 'shells' in the nucleus. When a shell is filled with just the right number of protons or neutrons, it becomes massively difficult to add or take away particles. These are 'magic' numbers, and have been thought to include 2, 8, 20, 28, 50, 82 and 126 particles. If a nucleus has a magic number of both neutrons and protons, it becomes 'doubly magic' -- and therefore even more stable. The most abundant form of oxygen, ^16O, is doubly magic, because of its eight protons and eight neutrons. Oxygen-28, with 8 protons and 20 neutrons, has long been predicted to be doubly magic, too. But physicists have not been able to detect it before. Ghost hunters Observing ^28O required several experimental feats. Key to the whole operation were the intense streams of radioactive isotopes produced by the Riken RI Beam Factory in Wako, Japan. The scientists fired a beam of calcium-48 isotopes at a beryllium target, which created a fluorine-29 isotope. The nucleus of this isotope has one more proton than does ^28O but the same number of neutrons. The scientists next smashed ^29F into a thick barrier of liquid hydrogen, knocking a proton out of the nucleus and generating ^28O. The a group photo of the team and the Oxygen-28 experiment setup at the RIKEN Radioactive Isotope Beam Factory. A large international team of researchers used instruments at the Riken RI Beam Factory to detect oxygen-28.Credit: Yosuke Kondo This rare form of oxygen was too short-lived to be observed directly. Instead, the team detected its decay products: oxygen-24 plus four neutrons, a measurement that seemed impossible only a few years ago. Measuring up to two neutrons at the same time has been done, but this is the first time scientists have detected four simultaneously, Nakamura says. "They are like ghosts," he says of neutrons. With no electrical charge, neutrons can't be wrangled in the same way that protons can (^24O, with its eight positively charged protons, could be ushered into a detector with magnets). To observe individual neutrons, the team used a powerful detector built for that purpose, on loan from the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany, in addition to Riken's instruments. In this specialized detector, incoming neutrons are revealed when they knock protons around. Nakamura says that the study's lead author, Tokyo Institute of Technology physicist Yosuke Kondo, used simulations to help to verify these tricky measurements. "They've really done their homework," says Robert Janssens, a physicist at the University of North Carolina at Chapel Hill. "They did all the checks you could do. It's a tour de force." Atomic limits Although the team wasn't able to get an exact measurement of the lifetime of ^28O, Nakamura says that the isotope did not behave as if it were doubly magic -- it fell apart almost as soon as it came into existence. "I was surprised," he says. "Personally, I thought it was doubly magic. But this is what nature says." [d41586-023] Extreme chemistry: experiments at the edge of the periodic table This is not the first hint that nuclear physicists' list of magic numbers is not universally applicable, says Rituparna Kanungo, a physicist at Saint Mary's University in Halifax, Canada. She was part of a team of scientists that showed in 2009 that ^24O -- contrary to the nuclear rulebook -- has a nucleus that behaves as though it is doubly magic^2. Its 8 protons and 16 neutrons are strongly bound to one another, giving it a relatively long lifetime -- it takes about 61 milliseconds for half of the ^24O to disappear through radioactive decay. This means that in some nuclei, if they are strongly bound, 16 could be a magic number, too. "Magic numbers are not immutable," Janssens says. For now, the confounding qualities of ^28O raise a whole host of questions about the forces that hold nuclei together. Physicists are daydreaming about possible next steps. Nakamura wants to see whether it's possible to detect oxygen-30. Because the stability of different isotopes is a relative measurement, it would be helpful to compare ^ 28O with this heavier, yet-unseen, near neighbour. "It's so simple and so complicated," Janssens says. "We don't know at the moment how many protons and neutrons you can put together in a nucleus" and have them stay bound together, he adds. "In other words, what's the limit?" doi: https://doi.org/10.1038/d41586-023-02713-3 Read the related News & Views: 'Heaviest oxygen isotope isfound to be unbound' References 1. Kondo, Y. et al. Nature https://doi.org/10.1038/ s41586-023-06352-6 (2023). Article Google Scholar 2. Kanungo, R. et al. Phys. Rev. Lett. 102, 152501 (2009). Article PubMed Google Scholar Download references Reprints and Permissions Related Articles * [d41586-023] Long-awaited accelerator ready to explore origins of elements * [d41586-023] Extreme chemistry: experiments at the edge of the periodic table * [d41586-023] Element 117 hints at 'island of stability' on periodic table Subjects * Physical chemistry * Nuclear physics Latest on: Physical chemistry Structure evolution at the gate-tunable suspended graphene-water interface Structure evolution at the gate-tunable suspended graphene-water interface Article 30 AUG 23 Microstructure and crystal order during freezing of supercooled water drops Microstructure and crystal order during freezing of supercooled water drops Article 16 AUG 23 Reversible spin-optical interface in luminescent organic radicals Reversible spin-optical interface in luminescent organic radicals Article 16 AUG 23 Nuclear physics First observation of 28O First observation of 28O Article 30 AUG 23 Heaviest oxygen isotope is found to be unbound Heaviest oxygen isotope is found to be unbound News & Views 30 AUG 23 Why Oppenheimer has important lessons for scientists today Why Oppenheimer has important lessons for scientists today News Q&A 26 JUL 23 Nature Careers Jobs * Postdoctoral Fellowships in Computational Biology Houston, Texas (US) The University of Texas MD Anderson Cancer Center [] * Postdoctoral Fellowships in Cancer Biology, CRISPR, and Epigenetics Houston, Texas (US) The University of Texas MD Anderson Cancer Center [] * Discovery Area Leader in Respiratory The Position In Roche's Pharmaceutical Research and Early Development organization (pRED), we make transformative medicines for patients in order t... Basel, Canton of Basel-Stadt (CH) F. Hoffmann-La Roche AG [] * W3- or W2-Professor with tenure track to W3 for Theoretical Solid-State Physics The Department of Physics and Astronomy at the Friedrich Schiller University Jena (Germany) is seeking for the summer semester 2024 a W3- or W2-P... 07743, Zentrum (DE) Friedrich-Schiller-Universitat Jena [] * Physician-Scientist Faculty Position at Baylor College of Medicine / Texas Children's Hospital Baylor College of Medicine / Texas Children's Hospital are recruiting multiple accomplished physician-scientists to develop their own research labs Houston, Texas (US) Baylor College of Medicine - Research Vision [] You have full access to this article via your institution. Download PDF Related Articles * [d41586-023] Long-awaited accelerator ready to explore origins of elements * [d41586-023] Extreme chemistry: experiments at the edge of the periodic table * [d41586-023] Element 117 hints at 'island of stability' on periodic table Subjects * Physical chemistry * Nuclear physics Advertisement Sign up to Nature Briefing An essential round-up of science news, opinion and analysis, delivered to your inbox every weekday. Email address [ ] [ ] Yes! Sign me up to receive the daily Nature Briefing email. I agree my information will be processed in accordance with the Nature and Springer Nature Limited Privacy Policy. Sign up * Close Nature Briefing Sign up for the Nature Briefing newsletter -- what matters in science, free to your inbox daily. Email address [ ] Sign up [ ] I agree my information will be processed in accordance with the Nature and Springer Nature Limited Privacy Policy. Close Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing Explore content * Research articles * News * Opinion * Research Analysis * Careers * Books & Culture * Podcasts * Videos * Current issue * Browse issues * Collections * Subjects * Follow us on Facebook * Follow us on Twitter * Subscribe * Sign up for alerts * RSS feed About the journal * Journal Staff * About the Editors * Journal Information * Our publishing models * Editorial Values Statement * Journal Metrics * Awards * Contact * Editorial policies * History of Nature * Send a news tip Publish with us * For Authors * For Referees * Language editing services * Submit manuscript Search Search articles by subject, keyword or author [ ] Show results from [All journals] Search Advanced search Quick links * Explore articles by subject * Find a job * Guide to authors * Editorial policies Nature (Nature) ISSN 1476-4687 (online) ISSN 0028-0836 (print) nature.com sitemap About Nature Portfolio * About us * Press releases * Press office * Contact us Discover content * Journals A-Z * Articles by subject * Nano * Protocol Exchange * Nature Index Publishing policies * Nature portfolio policies * Open access Author & Researcher services * Reprints & permissions * Research data * Language editing * Scientific editing * Nature Masterclasses * Live Expert Trainer-led workshops * Research Solutions Libraries & institutions * Librarian service & tools * Librarian portal * Open research * Recommend to library Advertising & partnerships * Advertising * Partnerships & Services * Media kits * Branded content Career development * Nature Careers * Nature Conferences * Nature events Regional websites * Nature Africa * Nature China * Nature India * Nature Italy * Nature Japan * Nature Korea * Nature Middle East * Privacy Policy * Use of cookies * Your privacy choices/Manage cookies * Legal notice * Accessibility statement * Terms & Conditions * Your US state privacy rights Springer Nature (c) 2023 Springer Nature Limited