Physics:Borromean nucleus
| Nuclear physics |
|---|
 |
| Nucleus · Nucleons (p, n) · Nuclear matter · Nuclear force · Nuclear structure · Nuclear reaction |
A Borromean nucleus is an atomic nucleus comprising three bound components in which any subsystem of two components is unbound.[1] This has the consequence that if one component is removed, the remaining two comprise an unbound resonance, so that the original nucleus is split into three parts.[2]
The name is derived from the Borromean rings, a system of three linked rings in which no pair of rings is linked.[2]
Examples of Borromean nuclei
Many Borromean nuclei are light nuclei near the nuclear drip lines that have a nuclear halo and low nuclear binding energy. For example, the nuclei The element Chemistry:helium does not exist., The element Chemistry:lithium does not exist., and The element Chemistry:carbon does not exist. each possess a two-neutron halo surrounding a core containing the remaining nucleons.[2][3] These are Borromean nuclei because the removal of either neutron from the halo will result in a resonance unbound to one-neutron emission, whereas the dineutron (the particles in the halo) is itself an unbound system.[1] Similarly, The element Chemistry:neon does not exist. is a Borromean nucleus with a two-proton halo; both the diproton and The element Chemistry:fluorine does not exist. are unbound.[4]
Additionally, The element Chemistry:beryllium does not exist. is a Borromean nucleus comprising two alpha particles and a neutron;[3] the removal of any one component would produce one of the unbound resonances The element Chemistry:helium does not exist. or The element Chemistry:beryllium does not exist..
Several Borromean nuclei such as The element Chemistry:beryllium does not exist. and the Hoyle state (an excited resonance in The element Chemistry:carbon does not exist.) play an important role in nuclear astrophysics. Namely, these are three-body systems whose unbound components (formed from The element Chemistry:helium does not exist.) are intermediate steps in the triple-alpha process; this limits the rate of production of heavier elements, for three bodies must react nearly simultaneously.[3]
Borromean nuclei consisting of more than three components can also exist. These also lie along the drip lines; for instance, The element Chemistry:helium does not exist. is a five-body Borromean system with a four-neutron halo.[5] It is also possible that nuclides produced in the alpha process (such as The element Chemistry:carbon does not exist. and The element Chemistry:oxygen does not exist.) may be clusters of alpha particles, having a similar structure to Borromean nuclei.[2]
As of 2012[update], the heaviest known Borromean nucleus was The element Chemistry:fluorine does not exist..[6] Heavier species along the neutron drip line have since been observed; these and undiscovered heavier nuclei along the drip line are also likely to be Borromean nuclei with varying numbers (3, 5, 7, or more) of bodies.[5]
See also
References
- ↑ 1.0 1.1 Id Betan, R. M. (2017). "Cooper pairs in the Borromean nuclei 6He and 11Li using continuum single particle level density". Nuclear Physics A 959: 147–148. doi:10.1016/j.nuclphysa.2017.01.004. Bibcode: 2017NuPhA.959..147I.
- ↑ 2.0 2.1 2.2 2.3 Manton, N.; Mee, N. (2017). "Nuclear Physics". The Physical World: An Inspirational Tour of Fundamental Physics. Oxford University Press. pp. 387–389. doi:10.1093/oso/9780198795933.003.0012. ISBN 978-0-19-879611-4.
- ↑ 3.0 3.1 3.2 Vaagen, J. S.; Gridnev, D. K.; Heiberg-Andersen, H. et al. (2000). "Borromean Halo Nuclei". Physica Scripta T88 (1): 209–213. doi:10.1238/Physica.Topical.088a00209. Bibcode: 2000PhST...88..209V. http://nrv.jinr.ru/pdf_file/physscr0_T88_039.pdf.
- ↑ Oishi, T.; Hagino, K.; Sagawa, H. (2010). "Diproton correlation in the proton-rich Borromean nucleus 17Ne". Physical Review C 82 (6): 066901–1–066901–6. doi:10.1103/PhysRevC.82.069901.
- ↑ 5.0 5.1 Riisager, K. (2013). "Halos and related structures". Physica Scripta 2013 (14001): 014001. doi:10.1088/0031-8949/2013/T152/014001. Bibcode: 2013PhST..152a4001R.
- ↑ Gaudefroy, L.; Mittig, W.; Orr, N. A. et al. (2012). "Direct Mass Measurements of 19B, 22C, 29F, 31Ne, 34Na and Other Light Exotic Nuclei". Physical Review Letters 109 (20): 202503–1–202503–5. doi:10.1103/PhysRevLett.109.202503. PMID 23215476.
 |  |
