Curium-248

Isotopes of curium

Isotopes of curium

Artificial nuclides with atomic number of 96 but with different mass numbers

Curium (96Cm) is an artificial element with an atomic number of 96. Because it is an artificial element, a standard atomic weight cannot be given, and it has no stable isotopes. The first isotope synthesized was 242Cm in 1944, which has 146 neutrons.

Quick Facts Main isotopes, Decay ...

There are 19 known radioisotopes ranging from 233Cm to 251Cm. There are also ten known nuclear isomers. The longest-lived isotope is 247Cm, with half-life 15.6 million years – orders of magnitude longer than that of any known isotope beyond curium, and long enough to study as a possible extinct radionuclide that would be produced by the r-process.[2][3] The longest-lived isomer is 246mCm with a half-life of 1.12 seconds.

List of isotopes

More information Nuclide, Z ...
  1. [n 1]
    mCm – Excited nuclear isomer.
  2. [n 2]
    ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
  3. [n 3]
    # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
  4. [n 4]
    # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
  5. [n 5]
    Modes of decay:
    CD:Cluster decay
    EC:Electron capture
    SF:Spontaneous fission
  6. [n 6]
    ( ) spin value – Indicates spin with weak assignment arguments.
  7. [n 7]
    Most common isotopes
  8. [n 8]
    Theoretically capable of β+β+ decay to 242Pu[1]
  9. [n 9]
    Heaviest known nuclide to undergo cluster decay
  10. [N 10]
    The nuclide with the lowest atomic number known to undergo spontaneous fission as the main decay mode

Actinides vs fission products

More information Half-life range (a), 4n ...

References

  1. [1]
    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.
  2. [2]
    Côté, Benoit; Eichler, Marius; Yagüe López, Andrés; Vassh, Nicole; Mumpower, Matthew R.; Világos, Blanka; Soós, Benjámin; Arcones, Almudena; Sprouse, Trevor M.; Surman, Rebecca; Pignatari, Marco; Pető, Mária K.; Wehmeyer, Benjamin; Rauscher, Thomas; Lugaro, Maria (26 February 2021). "129 I and 247 Cm in meteorites constrain the last astrophysical source of solar r-process elements". Science. 371 (6532): 945–948. arXiv:2006.04833. Bibcode:2021Sci...371..945C. doi:10.1126/science.aba1111. PMID 33632846. S2CID 232050526.
  3. [3]
    Davis, A.M.; McKeegan, K.D. (2014). "Short-Lived Radionuclides and Early Solar System Chronology". Treatise on Geochemistry: 383. doi:10.1016/B978-0-08-095975-7.00113-3. ISBN 9780080983004.
  4. [4]
    Khuyagbaatar, J.; Heßberger, F. P.; Hofmann, S.; Ackermann, D.; Burkhard, H. G.; Heinz, S.; Kindler, B.; Kojouharov, I.; Lommel, B.; Mann, R.; Maurer, J.; Nishio, K. (12 October 2020). "α decay of Fm 243 143 and Fm 245 145 , and of their daughter nuclei". Physical Review C. 102 (4): 044312. doi:10.1103/PhysRevC.102.044312. ISSN 2469-9985. S2CID 241259726. Retrieved 24 June 2023.
  5. [5]
    Khuyagbaatar, J.; Heßberger, F. P.; Hofmann, S.; Ackermann, D.; Comas, V. S.; Heinz, S.; Heredia, J. A.; Kindler, B.; Kojouharov, I.; Lommel, B.; Mann, R.; Nishio, K.; Yakushev, A. (1 October 2010). "The new isotope 236Cm and new data on 233Cm and 237, 238, 240Cf" (PDF). The European Physical Journal A. 46 (1): 59–67. Bibcode:2010EPJA...46...59K. doi:10.1140/epja/i2010-11026-9. ISSN 1434-601X. S2CID 122809010. Retrieved 24 June 2023.
  6. [6]
    Asai, M.; Tsukada, K.; Ichikawa, S.; Sakama, M.; Haba, H.; Nishinaka, I.; Nagame, Y.; Goto, S.; Kojima, Y.; Oura, Y.; Shibata, M. (20 June 2006). "α decay of 238Cm and the new isotope 237Cm". Physical Review C. 73 (6): 067301. doi:10.1103/PhysRevC.73.067301. Retrieved 24 June 2023.
  7. [7]
    Plus radium (element 88). While actually a sub-actinide, it immediately precedes actinium (89) and follows a three-element gap of instability after polonium (84) where no nuclides have half-lives of at least four years (the longest-lived nuclide in the gap is radon-222 with a half life of less than four days). Radium's longest lived isotope, at 1,600 years, thus merits the element's inclusion here.
  8. [8]
    Specifically from thermal neutron fission of uranium-235, e.g. in a typical nuclear reactor.
  9. [9]
    Milsted, J.; Friedman, A. M.; Stevens, C. M. (1965). "The alpha half-life of berkelium-247; a new long-lived isomer of berkelium-248". Nuclear Physics. 71 (2): 299. Bibcode:1965NucPh..71..299M. doi:10.1016/0029-5582(65)90719-4.
    "The isotopic analyses disclosed a species of mass 248 in constant abundance in three samples analysed over a period of about 10 months. This was ascribed to an isomer of Bk248 with a half-life greater than 9 [years]. No growth of Cf248 was detected, and a lower limit for the β− half-life can be set at about 104 [years]. No alpha activity attributable to the new isomer has been detected; the alpha half-life is probably greater than 300 [years]."
  10. [10]
    This is the heaviest nuclide with a half-life of at least four years before the "sea of instability".
  11. [11]
    Excluding those "classically stable" nuclides with half-lives significantly in excess of 232Th; e.g., while 113mCd has a half-life of only fourteen years, that of 113Cd is eight quadrillion years.
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