List of isotopes

Stellar nucleosynthesis of cobalt-56

One of the terminal nuclear reactions in stars prior to supernova produces 56Ni. Following its production, 56Ni decays to 56Co, and then 56Co subsequently decays to 56Fe. These decay reactions power the luminosity displayed in light decay curves. Both the light decay and radioactive decay curves are expected to be exponential. Therefore, the light decay curve should give an indication of the nuclear reactions powering it. This has been confirmed by observation of bolometric light decay curves for SN 1987A. Between 600 and 800 days after SN1987A occurred, the bolometric light curve decreased at an exponential rate with half-life values from τ1/2 = 68.6 days to τ1/2 = 69.6 days.²⁰ The rate at which the luminosity decreased closely matched the exponential decay of 56Co with a half-life of τ1/2 = 77.233 days.

Use of cobalt radioisotopes in medicine

Cobalt-57 (57Co or Co-57) is used in medical tests; it is used as a radiolabel for vitamin B12 uptake. It is useful for the Schilling test.²¹

Cobalt-60 (60Co or Co-60) is used in radiotherapy. It produces two gamma rays with energies of 1.17 MeV and 1.33 MeV. The 60Co source is about 2 cm in diameter and as a result produces a geometric penumbra, making the edge of the radiation field fuzzy. The metal has the unfortunate habit of producing fine dust, causing problems with radiation protection. The 60Co source is useful for about 5 years but even after this point is still very radioactive, and so cobalt machines have fallen from favor in the Western world where Linacs are common.

Industrial uses for radioactive isotopes

Cobalt-60 (60Co) is useful as a gamma ray source because it can be produced in predictable quantities, and for its high radioactivity simply by exposing natural cobalt to neutrons in a reactor.²² The uses for industrial cobalt include:

• Sterilization of medical supplies and medical waste
• Radiation treatment of foods for sterilization (cold pasteurization)²³
• Industrial radiography (e.g., weld integrity radiographs)
• Density measurements (e.g., concrete density measurements)
• Tank fill height switches

57Co is used as a source in Mössbauer spectroscopy of iron-containing samples. Electron capture by 57Co forms an excited state of the 57Fe nucleus, which in turn decays to the ground state with the emission of a gamma ray. Measurement of the gamma-ray spectrum provides information about the chemical state of the iron atom in the sample.

• Isotope masses from:
  • Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
• Half-life, spin, and isomer data selected from the following sources.
  • Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
  • National Nuclear Data Center. "NuDat 2.x database". Brookhaven National Laboratory.
  • Holden, Norman E. (2004). "11. Table of the Isotopes". In Lide, David R. (ed.). CRC Handbook of Chemistry and Physics (85th ed.). Boca Raton, Florida: CRC Press. ISBN 978-0-8493-0485-9.

References

1. Diaz, L. E. "Cobalt-57: Production". JPNM Physics Isotopes. University of Harvard. Archived from the original on 2000-10-31. Retrieved 2013-11-15. https://web.archive.org/web/20001031195522/http://www.med.harvard.edu/JPNM/physics/isotopes/Co/Co57/prod.html ↩

2. mCo – Excited nuclear isomer. /wiki/Nuclear_isomer ↩

3. Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*". Chinese Physics C. 45 (3): 030003. doi:10.1088/1674-1137/abddaf. /wiki/Doi_(identifier) ↩

4. ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits. ↩

5. # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS). ↩

6. Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae. https://www-nds.iaea.org/amdc/ame2020/NUBASE2020.pdf ↩

7. # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN). ↩

8. Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae. https://www-nds.iaea.org/amdc/ame2020/NUBASE2020.pdf ↩

9. Modes of decay: EC:Electron captureIT:Isomeric transitionn:Neutron emissionp:Proton emission /wiki/Electron_capture ↩

10. Bold symbol as daughter – Daughter product is stable. ↩

11. Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae. https://www-nds.iaea.org/amdc/ame2020/NUBASE2020.pdf ↩

12. ( ) spin value – Indicates spin with weak assignment arguments. ↩

13. # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN). ↩

14. # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN). ↩

15. Order of ground state and isomer is uncertain. ↩

16. Order of ground state and isomer is uncertain. ↩

17. Order of ground state and isomer is uncertain. ↩

18. Order of ground state and isomer is uncertain. ↩

19. Order of ground state and isomer is uncertain. ↩

20. Bouchet, P.; Danziger, I.J.; Lucy, L.B. (September 1991). "Bolometric Light Curve of SN 1987A: Results from Day 616 to 1316 After Outburst". The Astronomical Journal. 102 (3): 1135–1146. doi:10.1086/115939 – via Astrophysics Data System. https://doi.org/10.1086/115939 ↩

21. Diaz, L. E. "Cobalt-57: Uses". JPNM Physics Isotopes. University of Harvard. Archived from the original on 2011-06-11. Retrieved 2010-09-13. https://web.archive.org/web/20110611162615/http://www.med.harvard.edu/JPNM/physics/isotopes/Co/Co57/uses.html ↩

22. "Properties of Cobalt-60". Radioactive Isotopes. Retrieved 2022-12-09. http://radioactiveisotopes.weebly.com/properties-of-cobalt-60.html ↩

23. "Beneficial Uses of Cobalt-60". INTERNATIONAL IRRADIATION ASSOCIATION. Retrieved 2022-12-09. https://iiaglobal.com/publications/beneficial-uses-of-cobalt-60-2/ ↩