Isotopes of californium

(Redirected fromCalifornium-252)

Californium (₉₈Cf) is anartificial element, and thus astandard atomic weight cannot be given. Like all artificial elements, it has nostable isotopes. The firstisotope to be synthesized was²⁴⁵Cf in 1950. There are 20 knownradioisotopes ranging from²³⁷Cf to²⁵⁶Cf and onenuclear isomer,^249mCf. The longest-lived isotope is²⁵¹Cf with ahalf-life of 898 years.

Isotopes ofcalifornium (₉₈Cf)

Main isotopes^[1]^[2]			Decay
	abundance	half-life(t_1/2)	mode	product
²⁴⁸Cf	synth	333.5 d	α100%	²⁴⁴Cm
²⁴⁸Cf	synth	333.5 d	SF<0.01%	–
²⁴⁹Cf	synth	351 y	α100%	²⁴⁵Cm
²⁴⁹Cf	synth	351 y	SF≪0.01%	–
²⁵⁰Cf	synth	13.08 y	α99.9%	²⁴⁶Cm
²⁵⁰Cf	synth	13.08 y	SF0.08%	–
²⁵¹Cf	synth	898 y	α	²⁴⁷Cm
²⁵²Cf	synth	2.645 y	α96.9%	²⁴⁸Cm
²⁵²Cf	synth	2.645 y	SF3.09%	–
²⁵³Cf	synth	17.81 d	β⁻99.7%	²⁵³Es
²⁵³Cf	synth	17.81 d	α0.31%	²⁴⁹Cm
²⁵⁴Cf	synth	60.5 d	SF99.7%	–
²⁵⁴Cf	synth	60.5 d	α0.31%	²⁵⁰Cm

List of isotopes

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Cf-249

Cf-251

Nuclide ^{[n 1]}	Z	N	Isotopic mass(Da)^[3] ^{[n 2]}^{[n 3]}	Half-life^[4]	Decay mode^[4] ^{[n 4]}	Daughter isotope	Spin and parity^[4] ^{[n 5]}^{[n 6]}
Nuclide ^{[n 1]}	Excitation energy			Half-life^[4]	Decay mode^[4] ^{[n 4]}	Daughter isotope	Spin and parity^[4] ^{[n 5]}^{[n 6]}
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+
²³⁸Cf	98	140	238.06149(32)#	21.1(13) ms	α (<5%)	²³⁴Cm	0+
²³⁹Cf^[5]	98	141	239.06248(13)#	28(2) s	α (65%)	²³⁵Cm	(5/2+)
²³⁹Cf^[5]	98	141	239.06248(13)#	28(2) s	β⁺ (35%)	²³⁹Bk	(5/2+)
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−)
²⁴¹Cf^[5]	98	143	241.06369(18)#	2.35(18) min	α (15%)	²³⁷Cm	(7/2−)
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+)
²⁴³Cf	98	145	243.06548(19)#	10.8(3) min	α (14%)	²³⁹Cm	(1/2+)
²⁴⁴Cf	98	146	244.0659994(28)	19.5(5) min	α (75%)	²⁴⁰Cm	0+
²⁴⁴Cf	98	146	244.0659994(28)	19.5(5) min	EC (25%)	²⁴⁴Bk	0+
²⁴⁵Cf	98	147	245.0680468(26)	45.0(15) min	β⁺ (64.7%)	²⁴⁵Bk	1/2+
²⁴⁵Cf	98	147	245.0680468(26)	45.0(15) min	α (35.3%)	²⁴¹Cm	1/2+
^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+)
²⁴⁷Cf	98	149	247.070971(15)	3.11(3) h	α (.035%)	²⁴³Cm	(7/2+)
²⁴⁸Cf	98	150	248.0721829(55)	333.5(28) d	α (99.997%)	²⁴⁴Cm	0+
²⁴⁸Cf	98	150	248.0721829(55)	333.5(28) d	SF (.0029%)	(various)	0+
²⁴⁹Cf	98	151	249.0748504(13)	351(2) y	α	²⁴⁵Cm	9/2−
²⁴⁹Cf	98	151	249.0748504(13)	351(2) y	SF (5×10⁻⁷%)	(various)	9/2−
^249mCf	144.98(5) keV			45(5) μs	IT	²⁴⁹Cf	5/2+
²⁵⁰Cf	98	152	250.0764045(17)	13.08(9) y	α (99.923%)	²⁴⁶Cm	0+
²⁵⁰Cf	98	152	250.0764045(17)	13.08(9) y	SF (.077%)	(various)	0+
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+
²⁵²Cf^{[n 9]}	98	154	252.0816265(25)	2.645(8) y	SF (3.1028%)^{[n 10]}	(various)	0+
²⁵³Cf	98	155	253.0851337(46)	17.81(8) d	β⁻ (99.69%)	²⁵³Es	(7/2+)
²⁵³Cf	98	155	253.0851337(46)	17.81(8) d	α (.31%)	²⁴⁹Cm	(7/2+)
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: view

^^mCf – Excitednuclear 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 undergospontaneous fission as its main decay mode
^Highneutron cross-section, tends to absorb neutrons
^Most common isotope
^High neutron emitter, average 3.7neutrons perfission

Actinides vs fission products

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Actinides and fission products by half-life v t e
Actinides^[6] bydecay chain				Half-life range (a)	Fission products of²³⁵U byyield^[7]
4n	4n + 1	4n + 2	4n + 3	Half-life range (a)	4.5–7%	0.04–1.25%	<0.001%
²²⁸Ra^№				4–6 a		¹⁵⁵Eu^þ
²⁴⁸Bk^[8]				> 9 a
²⁴⁴Cm^ƒ	²⁴¹Pu^ƒ	²⁵⁰Cf	²²⁷Ac^№	10–29 a	⁹⁰Sr	⁸⁵Kr	^113mCd^þ
²³²U^ƒ		²³⁸Pu^ƒ	²⁴³Cm^ƒ	29–97 a	¹³⁷Cs	¹⁵¹Sm^þ	^121mSn
	²⁴⁹Cf^ƒ	^242mAm^ƒ		141–351 a	No fission products have ahalf-life in the range of 100 a–210 ka ...
	²⁴¹Am^ƒ		²⁵¹Cf^ƒ^[9]	430–900 a
		²²⁶Ra^№	²⁴⁷Bk	1.3–1.6 ka
²⁴⁰Pu	²²⁹Th	²⁴⁶Cm^ƒ	²⁴³Am^ƒ	4.7–7.4 ka
	²⁴⁵Cm^ƒ	²⁵⁰Cm		8.3–8.5 ka
			²³⁹Pu^ƒ	24.1 ka
		²³⁰Th^№	²³¹Pa^№	32–76 ka
²³⁶Np^ƒ	²³³U^ƒ	²³⁴U^№		150–250 ka	⁹⁹Tc^₡	¹²⁶Sn
²⁴⁸Cm		²⁴²Pu		327–375 ka		⁷⁹Se^₡
				1.33 Ma	¹³⁵Cs^₡
	²³⁷Np^ƒ			1.61–6.5 Ma	⁹³Zr	¹⁰⁷Pd
²³⁶U			²⁴⁷Cm^ƒ	15–24 Ma		¹²⁹I^₡
²⁴⁴Pu				80 Ma	... nor beyond 15.7 Ma^[10]
²³²Th^№		²³⁸U^№	²³⁵U^ƒ№	0.7–14.1 Ga	... nor beyond 15.7 Ma^[10]
₡, has thermalneutron capture cross section in the range of 8–50 barns ƒ, fissile №, primarily anaturally occurring radioactive material (NORM) þ, neutron poison (thermal neutron capture cross section greater than 3k barns)

Californium-252

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Californium-252 production diagram

Californium-252 (Cf-252,²⁵²Cf) undergoes spontaneous fission with abranching ratio of 3.09% and is used in smallneutron 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.^[11]

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

Nuclear reactors

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

Military and defense

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The portable isotopic neutron spectroscopy (PINS) used byUnited States Armed Forces, theNational Guard,Homeland Security, andCustoms and Border Protection, uses²⁵²Cf sources to detect hazardous contents insideartillery projectiles,mortar projectiles,rockets,bombs,land mines, andimprovised explosive devices (IED).^[12]^[13]

Oil and petroleum

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In theoil industry,²⁵²Cf is used to find layers ofpetroleum and water in awell. Instrumentation is lowered into the well, which bombards the formation with high energy neutrons to determineporosity,permeability, andhydrocarbon presence along the length of theborehole.^[14]

Medicine

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Californium-252 has also been used in the treatment of serious forms ofcancer. For certain types of brain and cervical cancer,²⁵²Cf can be used as a more cost-effective substitute forradium.^[15]

References

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^CRC 2006, p. 11.196.
^Sonzogni, Alejandro A. (Database Manager), ed. (2008)."Chart of Nuclides". National Nuclear Data Center, Brookhaven National Laboratory. Retrieved1 March 2010.
^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.
^^a ^b ^cKondev, 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.
^^a ^bKhuyagbaatar, 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. Retrieved24 June 2023.
^Plus radium (element 88). While actually a sub-actinide, it immediately precedes actinium (89) and follows a three-element gap of instability afterpolonium (84) where no nuclides have half-lives of at least four years (the longest-lived nuclide in the gap isradon-222 with a half life of less than fourdays). Radium's longest lived isotope, at 1,600 years, thus merits the element's inclusion here.
^Specifically fromthermal neutron fission of uranium-235, e.g. in a typicalnuclear reactor.
^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]."
^This is the heaviest nuclide with a half-life of at least four years before the "sea of instability".
^Excluding those "classically stable" nuclides with half-lives significantly in excess of²³²Th; e.g., while^113mCd has a half-life of only fourteen years, that of¹¹³Cd is eightquadrillion years.
^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.
^"Portable Isotopic Neutron Spectroscopy (PINS) for the Military".Frontier Technology Corp. Archived fromthe original on 2018-06-16. Retrieved2016-02-24.
^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.
^"Californium-252 & Antimony-Beryllium Sources".Frontier Technology Corp. Retrieved2016-02-24.
^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.