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Isotopes of californium

Californium (98Cf) is an artificial element, and thus a standard atomic weight cannot be given. Like all artificial elements, it has no stable isotopes. The first isotope to be synthesized was 245Cf in 1950. There are 20 known radioisotopes ranging from 237Cf to 256Cf and one nuclear isomer, 249mCf. The longest-lived isotope is 251Cf with a half-life of 898 years.

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List of isotopes

Nuclide1ZNIsotopic mass (Da)234Half-life5Decaymode67DaughterisotopeSpin andparity8910
Excitation energy
237Cf98139237.06220(10)0.8(2) sα (70%)233Cm5/2+#
SF (30%)(various)
238Cf98140238.06149(32)#21.1(13) msSF (97.5%)11(various)0+
α (2.5%)234Cm
239Cf98141239.06248(13)#28(2) sα (65%)235Cm5/2+#
β+? (35%)239Bk
240Cf98142240.062253(19)40.3(9) sα (98.5%)236Cm0+
SF (1.5%)(various)
241Cf98143241.06369(18)#2.35(18) minβ+? (85%)241Bk7/2−#
α (15%)237Cm
242Cf98144242.063755(14)3.49(15) minα (61%)238Cm0+
β+ (39%)242Bk
SF (<0.014%)(various)
243Cf98145243.06548(19)#10.8(3) minβ+ (86%)243Bk(1/2+)
α (14%)239Cm
244Cf98146244.0659994(28)19.5(5) minα (75%)240Cm0+
EC (25%)244Bk
245Cf98147245.0680468(26)45.0(15) minβ+ (64.7%)245Bk1/2+
α (35.3%)241Cm
245mCf57(4) keV>100# nsIT245Cf(7/2+)
246Cf98148246.0688037(16)35.7(5) hα242Cm0+
SF (2.4×10−4%)(various)
247Cf98149247.070971(15)3.11(3) hEC (99.965%)247Bk(7/2+)
α (0.035%)243Cm
248Cf98150248.072183(5)333.5(28) dα244Cm0+
SF (0.0029%)(various)
249Cf98151249.0748504(13)351(2) yα245Cm9/2−
SF (5×10−7%)(various)
249mCf144.98(5) keV45(5) μsIT249Cf5/2+
250Cf98152250.0764045(17)13.08(9) yα (99.923%)246Cm0+
SF (0.077%)(various)
251Cf1298153251.079587(4)898(44) yα247Cm1/2+
251mCf370.47(3) keV1.3(1) μsIT251Cf11/2−
252Cf1398154252.0816265(25)2.645(8) yα (96.8972%)248Cm0+
SF (3.1028%)14(various)
253Cf98155253.085134(5)17.81(8) dβ− (99.69%)253Es(7/2+)
α (0.31%)249Cm
254Cf1598156254.087324(12)60.5(2) dSF (99.69%)(various)0+
α (0.31%)250Cm
255Cf98157255.09105(22)#85(18) minβ−255Es(7/2+)
256Cf1698158256.09344(34)#12.3(12) minSF(various)0+
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Actinides vs fission products

Actinides and fission products by half-life
  • v
  • t
  • e
Actinides17 by decay chainHalf-life range (a)Fission products of 235U by yield18
4n4n + 14n + 24n + 34.5–7%0.04–1.25%<0.001%
228Ra№4–6 a155Euþ
248Bk19> 9 a
244Cmƒ241Puƒ250Cf227Ac№10–29 a90Sr85Kr113mCdþ
232238Puƒ243Cmƒ29–97 a137Cs151Smþ121mSn
249Cfƒ242mAmƒ141–351 a

No fission products have a half-lifein the range of 100 a–210 ka ...

241Amƒ251Cfƒ20430–900 a
226Ra№247Bk1.3–1.6 ka
240Pu229Th246Cmƒ243Amƒ4.7–7.4 ka
245Cmƒ250Cm8.3–8.5 ka
239Puƒ24.1 ka
230Th№231Pa№32–76 ka
236Npƒ233234U№150–250 ka99Tc₡126Sn
248Cm242Pu327–375 ka79Se₡
1.33 Ma135Cs₡
237Npƒ1.61–6.5 Ma93Zr107Pd
236U247Cmƒ15–24 Ma129I₡
244Pu80 Ma

... nor beyond 15.7 Ma21

232Th№238U№235Uƒ№0.7–14.1 Ga

Californium-252

Californium-252 (Cf-252, 252Cf) undergoes spontaneous fission with a branching ratio of 3.09% and is used in small neutron sources. Fission neutrons have an energy range of 0 to 13 MeV with a mean value of 2.3 MeV and a most probable value of 1 MeV.22

This isotope produces high neutron emissions and has a number of uses in industries such as nuclear energy, medicine, and petrochemical exploration.

Nuclear reactors

Californium-252 neutron sources are most notably used in the start-up of nuclear reactors. Once a reactor is filled with nuclear fuel, the stable neutron emission from said source starts the chain reaction.

Military and defense

The portable isotopic neutron spectroscopy (PINS) used by United States Armed Forces, the National Guard, Homeland Security, and Customs and Border Protection, uses 252Cf sources to detect hazardous contents inside artillery projectiles, mortar projectiles, rockets, bombs, land mines, and improvised explosive devices (IED).2324

Oil and petroleum

In the oil industry, 252Cf is used to find layers of petroleum and water in a well. Instrumentation is lowered into the well, which bombards the formation with high energy neutrons to determine porosity, permeability, and hydrocarbon presence along the length of the borehole.25

Medicine

Californium-252 has also been used in the treatment of serious forms of cancer. For certain types of brain and cervical cancer, 252Cf can be used as a more cost-effective substitute for radium.26

Sources

  • Lide, David R., ed. (2006). Handbook of Chemistry and Physics (87th ed.). CRC Press, Taylor & Francis Group. ISBN 978-0-8493-0487-3.

References

  1. mCf – Excited nuclear isomer. /wiki/Nuclear_isomer

  2. 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)

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

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

  5. 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

  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. Modes of decay: EC:Electron captureSF:Spontaneous fission /wiki/Electron_capture

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

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

  11. Lightest nuclide known to undergo spontaneous fission as its main decay mode /wiki/Spontaneous_fission

  12. High neutron cross-section, tends to absorb neutrons /wiki/Neutron_cross-section

  13. Most common isotope

  14. High neutron emitter, average 3.7 neutrons per fission /wiki/Neutron

  15. Theoretically capable of β−β− decay to 254Fm

  16. Theoretically capable of β−β− decay to 256Fm or perhaps β− decay to 256Es

  17. 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. /wiki/Polonium

  18. Specifically from thermal neutron fission of uranium-235, e.g. in a typical nuclear reactor. /wiki/Thermal_neutron

  19. 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]." /wiki/Bibcode_(identifier)

  20. This is the heaviest nuclide with a half-life of at least four years before the "sea of instability". /wiki/Sea_of_instability

  21. 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. /wiki/Primordial_nuclide

  22. Dicello, J. F.; Gross, W.; Kraljevic, U. (1972). "Radiation Quality of Californium-252". Physics in Medicine and Biology. 17 (3): 345–355. Bibcode:1972PMB....17..345D. doi:10.1088/0031-9155/17/3/301. PMID 5070445. S2CID 250786668. /wiki/Physics_in_Medicine_and_Biology

  23. "Portable Isotopic Neutron Spectroscopy (PINS) for the Military". Frontier Technology Corp. Archived from the original on 2018-06-16. Retrieved 2016-02-24. https://web.archive.org/web/20180616132135/http://www.frontier-cf252.com/portable-isotopic-neutron-spectroscopy-military.html

  24. Martin, R. C.; Knauer, J. B.; Balo, P. A. (2000-11-01). "Production, distribution and applications of californium-252 neutron sources". Applied Radiation and Isotopes. 53 (4–5): 785–792. doi:10.1016/s0969-8043(00)00214-1. ISSN 0969-8043. PMID 11003521. https://digital.library.unt.edu/ark:/67531/metadc623566/

  25. "Californium-252 & Antimony-Beryllium Sources". Frontier Technology Corp. Retrieved 2016-02-24. https://www.frontier-cf252.com

  26. Maruyama, Y.; van Nagell, J. R.; Yoneda, J.; Donaldson, E.; Hanson, M.; Martin, A.; Wilson, L. C.; Coffey, C. W.; Feola, J. (1984-10-01). "Five-year cure of cervical cancer treated using californium-252 neutron brachytherapy". American Journal of Clinical Oncology. 7 (5): 487–493. doi:10.1097/00000421-198410000-00018. ISSN 0277-3732. PMID 6391143. S2CID 12553815. /wiki/Doi_(identifier)