Isotopes of californium
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List of isotopes
Nuclide [n 1] |
Z | N | Isotopic mass (Da)[3] [n 2][n 3] |
Half-life[4] |
Daughter isotope |
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Excitation energy | |||||||||||||||||||
237Cf | 98 | 139 | 237.06220(10) | 0.8(2) s | α (70%) | 233Cm | 5/2+# | ||||||||||||
SF (30%) | (various) | ||||||||||||||||||
β+ (rare) | 237Bk | ||||||||||||||||||
238Cf | 98 | 140 | 238.06149(32)# | 21.1(13) ms | SF[n 7] | (various) | 0+ | ||||||||||||
α (<5%) | 234Cm | ||||||||||||||||||
239Cf[5] | 98 | 141 | 239.06248(13)# | 28(2) s | α (65%) | 235Cm | (5/2+) | ||||||||||||
β+ (35%) | 239Bk | ||||||||||||||||||
240Cf | 98 | 142 | 240.062253(19) | 40.3(9) s | α (98.5%) | 236Cm | 0+ | ||||||||||||
SF (1.5%) | (various) | ||||||||||||||||||
β+? | 240Bk | ||||||||||||||||||
241Cf[5] | 98 | 143 | 241.06369(18)# | 2.35(18) min | β+ (85%) | 241Bk | (7/2−) | ||||||||||||
α (15%) | 237Cm | ||||||||||||||||||
242Cf | 98 | 144 | 242.063755(14) | 3.49(15) min | α (61%) | 238Cm | 0+ | ||||||||||||
β+ (39%) | 242Bk | ||||||||||||||||||
SF (<0.014%) | (various) | ||||||||||||||||||
243Cf | 98 | 145 | 243.06548(19)# | 10.8(3) min | β+ (86%) | 243Bk | (1/2+) | ||||||||||||
α (14%) | 239Cm | ||||||||||||||||||
244Cf | 98 | 146 | 244.0659994(28) | 19.5(5) min | α (75%) | 240Cm | 0+ | ||||||||||||
EC (25%) | 244Bk | ||||||||||||||||||
245Cf | 98 | 147 | 245.0680468(26) | 45.0(15) min | β+ (64.7%) | 245Bk | 1/2+ | ||||||||||||
α (35.3%) | 241Cm | ||||||||||||||||||
245mCf | 57(4) keV | >100# ns | IT | 245Cf | (7/2+) | ||||||||||||||
246Cf | 98 | 148 | 246.0688037(16) | 35.7(5) h | α | 242Cm | 0+ | ||||||||||||
SF (2.4×10−4%) | (various) | ||||||||||||||||||
EC? | 246Bk | ||||||||||||||||||
247Cf | 98 | 149 | 247.070971(15) | 3.11(3) h | EC (99.965%) | 247Bk | (7/2+) | ||||||||||||
α (.035%) | 243Cm | ||||||||||||||||||
248Cf | 98 | 150 | 248.0721829(55) | 333.5(28) d | α (99.997%) | 244Cm | 0+ | ||||||||||||
SF (.0029%) | (various) | ||||||||||||||||||
249Cf | 98 | 151 | 249.0748504(13) | 351(2) y | α | 245Cm | 9/2− | ||||||||||||
SF (5×10−7%) | (various) | ||||||||||||||||||
249mCf | 144.98(5) keV | 45(5) μs | IT
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249Cf | 5/2+ | ||||||||||||||
250Cf | 98 | 152 | 250.0764045(17) | 13.08(9) y | α (99.923%) | 246Cm | 0+ | ||||||||||||
SF (.077%) | (various) | ||||||||||||||||||
251Cf[n 8] | 98 | 153 | 251.0795872(42) | 898(44) y | α | 247Cm | 1/2+ | ||||||||||||
251mCf | 370.47(3) keV | 1.3(1) μs | IT | 251Cf | 11/2− | ||||||||||||||
252Cf[n 9] | 98 | 154 | 252.0816265(25) | 2.645(8) y | α (96.8972%) | 248Cm | 0+ | ||||||||||||
SF (3.1028%)[n 10] | (various) | ||||||||||||||||||
253Cf | 98 | 155 | 253.0851337(46) | 17.81(8) d | β− (99.69%) | 253Es | (7/2+) | ||||||||||||
α (.31%) | 249Cm | ||||||||||||||||||
254Cf | 98 | 156 | 254.087324(12) | 60.5(2) d | SF (99.69%) | (various) | 0+ | ||||||||||||
α (.31%) | 250Cm | ||||||||||||||||||
β−β−? | 254Fm | ||||||||||||||||||
255Cf | 98 | 157 | 255.09105(22)# | 85(18) min | β− | 255Es | (7/2+) | ||||||||||||
SF? | (various) | ||||||||||||||||||
α? | 251Cm | ||||||||||||||||||
256Cf | 98 | 158 | 256.09344(34)# | 12.3(12) min | SF | (various) | 0+ | ||||||||||||
α? | 252Cm | ||||||||||||||||||
β−β−? | 256Fm | ||||||||||||||||||
This table header & footer: |
- ^ mCf – Excited nuclear isomer.
- ^ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
- ^ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
- ^
Modes of decay:
EC: Electron capture SF: Spontaneous fission - ^ ( ) spin value – Indicates spin with weak assignment arguments.
- ^ # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
- ^ Lightest nuclide known to undergo spontaneous fission as its main decay mode
- neutron cross-section, tends to absorb neutrons
- ^ Most common isotope
- ^ High neutron emitter, average 3.7 neutrons per fission
Actinides vs fission products
Actinides[6] by decay chain | Half-life range (a) |
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4n
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4n + 1
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4n + 2
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4n + 3
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4.5–7% | 0.04–1.25% | <0.001% | ||
228 Ra№
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4–6 a
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155 Euþ
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244 Cmƒ
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241Puƒ | 250 Cf
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227 Ac№
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10–29 a
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90Sr | 85Kr | 113m Cdþ
| |
232Uƒ | 238Puƒ | 243 Cmƒ
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29–97 a
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137 Cs
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151 Smþ
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121m Sn
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248Bk[8]
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249 Cfƒ
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242m Amƒ
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141–351 a |
No fission products have a half-life | ||||
241Amƒ | 251Cfƒ[9]
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430–900 a | ||||||
226Ra№ | 247 Bk
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1.3–1.6 ka | ||||||
240Pu | 229 Th
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246 Cmƒ
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243 Amƒ
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4.7–7.4 ka | ||||
245 Cmƒ
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250 Cm
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8.3–8.5 ka | ||||||
239Puƒ | 24.1 ka | |||||||
230 Th№
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231 Pa№
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32–76 ka | ||||||
236 Npƒ
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233Uƒ | 234U№ | 150–250 ka | 99Tc₡ | 126 Sn
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248 Cm
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242Pu | 327–375 ka | 79Se₡ | |||||
1.53 Ma | 93 Zr
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237 Npƒ
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2.1–6.5 Ma | 135 Cs₡
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107 Pd
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236U | 247 Cmƒ
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15–24 Ma | 129I₡ | |||||
244Pu | 80 Ma |
... nor beyond 15.7 Ma[10] | ||||||
232Th№ | 238U№ | 235Uƒ№ | 0.7–14.1 Ga | |||||
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Californium-252
Californium-252 (Cf-252, 252Cf) undergoes spontaneous fission with a
This isotope produces high neutron emissions and can be used for a number of applications in industries such as nuclear energy, medicine, and petrochemical exploration.
Nuclear reactors
Neutron sources using 252Cf are most notably used in the start-up of nuclear reactors. Once a reactor is filled with nuclear fuel, the stable neutron emission from the source material 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).[12][13]
Oil and petroleum
In the
Medicine
252Cf 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.[15]
References
- ^ CRC 2006, p. 11.196.
- ^ Sonzogni, Alejandro A. (Database Manager), ed. (2008). "Chart of Nuclides". National Nuclear Data Center, Brookhaven National Laboratory. Retrieved 1 March 2010.
- .
- ^ .
- ^ S2CID 241259726. Retrieved 24 June 2023.
- ^ 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.
- thermal neutron fission of uranium-235, e.g. in a typical nuclear reactor.
- .
"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]." - sea of instability".
- ^ 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.
- S2CID 250786668.
- ^ "Portable Isotopic Neutron Spectroscopy (PINS) for the Military". Frontier Technology Corp. Archived from the original on 2018-06-16. Retrieved 2016-02-24.
- PMID 11003521.
- ^ "Californium-252 & Antimony-Beryllium Sources". Frontier Technology Corp. Retrieved 2016-02-24.
- S2CID 12553815.
Sources
- Lide, David R., ed. (2006). Handbook of Chemistry and Physics (87th ed.). CRC Press, Taylor & Francis Group. ISBN 978-0-8493-0487-3.