Isotopes of californium

Isotopes of californium (₉₈Cf)
SF<0.01%	–
SF≪0.01%	–
SF0.08%	–
SF3.1%	–
α0.31%	249Cm
α0.31%	250Cm

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 several short-lived nuclear isomers. The longest-lived isotope is ²⁵¹Cf with a half-life of 898 years; followed by ²⁴⁹Cf (available isotopically pure from decay of berkelium) at 351 years.

List of isotopes

Nuclide ^{[n 1]}	Z	N	Isotopic mass (Da)^[2] ^{[n 2]}^{[n 3]}	Discovery year^[3]^[4]	Half-life^[1]	Decay mode^[1] ^{[n 4]}	Daughter isotope	Spin and parity^[1] ^{[n 5]}^{[n 6]}
Nuclide ^{[n 1]}	Excitation energy			Discovery year^[3]^[4]	Half-life^[1]	Decay mode^[1] ^{[n 4]}	Daughter isotope	Spin and parity^[1] ^{[n 5]}^{[n 6]}
²³⁷Cf	98	139	237.06220(10)	1995	0.8(2) s	α (70%)	²³³Cm	5/2+#
²³⁷Cf	98	139	237.06220(10)	1995	0.8(2) s	SF (30%)	(various)	5/2+#
²³⁸Cf	98	140	238.06149(32)#	1995	21.1(13) ms	SF (97.5%)^{[n 7]}	(various)	0+
²³⁸Cf	98	140	238.06149(32)#	1995	21.1(13) ms	α (2.5%)	²³⁴Cm	0+
²³⁹Cf	98	141	239.06248(13)#	1981	28(2) s	α (65%)	²³⁵Cm	5/2+#
²³⁹Cf	98	141	239.06248(13)#	1981	28(2) s	β⁺? (35%)	²³⁹Bk	5/2+#
²⁴⁰Cf	98	142	240.062253(19)	1970	40.3(9) s	α (98.5%)	²³⁶Cm	0+
²⁴⁰Cf	98	142	240.062253(19)	1970	40.3(9) s	SF (1.5%)	(various)	0+
²⁴¹Cf	98	143	241.06369(18)#	1970	2.35(18) min	β⁺? (85%)	²⁴¹Bk	7/2−#
²⁴¹Cf	98	143	241.06369(18)#	1970	2.35(18) min	α (15%)	²³⁷Cm	7/2−#
²⁴²Cf	98	144	242.063755(14)	1967	3.49(15) min	α (61%)	²³⁸Cm	0+
						β⁺ (39%)	²⁴²Bk
						SF (<0.014%)	(various)
²⁴³Cf	98	145	243.06548(19)#	1967	10.8(3) min	β⁺ (86%)	²⁴³Bk	(1/2+)
²⁴³Cf	98	145	243.06548(19)#	1967	10.8(3) min	α (14%)	²³⁹Cm	(1/2+)
^243mCf	~315 keV			2021	5.1 s	α (?%)	²³⁹Cm	(7/2+)
²⁴⁴Cf	98	146	244.0659994(28)	1956	19.5(5) min	α (75%)	²⁴⁰Cm	0+
²⁴⁴Cf	98	146	244.0659994(28)	1956	19.5(5) min	EC (25%)	²⁴⁴Bk	0+
²⁴⁵Cf	98	147	245.0680468(26)	1956	45.0(15) min	β⁺ (64.7%)	²⁴⁵Bk	1/2+
²⁴⁵Cf	98	147	245.0680468(26)	1956	45.0(15) min	α (35.3%)	²⁴¹Cm	1/2+
^245mCf	57(4)keV			(2004)^{[n 8]}	>100# ns	IT	²⁴⁵Cf	(7/2+)
²⁴⁶Cf	98	148	246.0688037(16)	1951	35.7(5) h	α	²⁴²Cm	0+
²⁴⁶Cf	98	148	246.0688037(16)	1951	35.7(5) h	SF (2.4×10⁻⁴%)	(various)	0+
²⁴⁷Cf	98	149	247.070971(15)	1954	3.11(3) h	EC (99.965%)	²⁴⁷Bk	(7/2+)
²⁴⁷Cf	98	149	247.070971(15)	1954	3.11(3) h	α (0.035%)	²⁴³Cm	(7/2+)
²⁴⁸Cf	98	150	248.072183(5)	1954	333.5(28) d	α	²⁴⁴Cm	0+
²⁴⁸Cf	98	150	248.072183(5)	1954	333.5(28) d	SF (0.0029%)	(various)	0+
^248mCf	900(300) keV			2020	~139 ns	IT?	²⁴⁸Cf
²⁴⁹Cf	98	151	249.0748504(13)	1954	351(2) y	α	²⁴⁵Cm	9/2−
²⁴⁹Cf	98	151	249.0748504(13)	1954	351(2) y	SF (5×10⁻⁷%)	(various)	9/2−
^249mCf	144.98(5) keV			1967	45(5) μs	IT	²⁴⁹Cf	5/2+
²⁵⁰Cf	98	152	250.0764045(17)	1954	13.08(9) y	α (99.923%)	²⁴⁶Cm	0+
²⁵⁰Cf	98	152	250.0764045(17)	1954	13.08(9) y	SF (0.077%)	(various)	0+
²⁵¹Cf^{[n 9]}	98	153	251.079587(4)	1954	898(44) y	α	²⁴⁷Cm	1/2+
^251mCf	370.47(3) keV			1971	1.3(1) μs	IT	²⁵¹Cf	11/2−
²⁵²Cf^{[n 10]}	98	154	252.0816265(25)	1954	2.645(8) y	α (96.8972%)	²⁴⁸Cm	0+
²⁵²Cf^{[n 10]}	98	154	252.0816265(25)	1954	2.645(8) y	SF (3.1028%)^{[n 11]}	(various)	0+
²⁵³Cf	98	155	253.085134(5)	1954	17.81(8) d	β⁻ (99.69%)	²⁵³Es	(7/2+)
²⁵³Cf	98	155	253.085134(5)	1954	17.81(8) d	α (0.31%)	²⁴⁹Cm	(7/2+)
²⁵⁴Cf^{[n 12]}	98	156	254.087324(12)	1955	60.5(2) d	SF (99.69%)	(various)	0+
²⁵⁴Cf^{[n 12]}	98	156	254.087324(12)	1955	60.5(2) d	α (0.31%)	²⁵⁰Cm	0+
²⁵⁵Cf	98	157	255.09105(22)#	1981	85(18) min	β⁻	²⁵⁵Es	(7/2+)
²⁵⁶Cf^{[n 13]}	98	158	256.09344(34)#	1980	12.3(12) min	SF	(various)	0+
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
^ Half-life not measured, not included in discovery database
^ High neutron cross-section, tends to absorb neutrons
^ Most common isotope
^ High neutron emitter, average 3.7 neutrons per fission
^ Theoretically capable of β⁻β⁻ decay to ²⁵⁴Fm
^ Theoretically capable of β⁻β⁻ decay to ²⁵⁶Fm or perhaps β⁻ decay to ²⁵⁶Es

Actinides vs fission products

Actinides and fission products by half-life
Actinides^[5] by decay chain				Half-life range (a)	Fission products of ²³⁵U by yield^[6]
4n (Thorium)	4n + 1 (Neptunium)	4n + 2 (Radium)	4n + 3 (Actinium)	Half-life range (a)	4.5–7%	0.04–1.25%	<0.001%
²²⁸Ra^№				4–6 a		¹⁵⁵Eu^þ
²⁴⁸Bk^[7]				> 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 a half-life in the range of 100 a–210 ka ...
	²⁴¹Am^ƒ		²⁵¹Cf^ƒ^[8]	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^[9]
²³²Th^№		²³⁸U^№	²³⁵U^ƒ№	0.7–14.1 Ga	... nor beyond 15.7 Ma^[9]
₡, has thermal neutron capture cross section in the range of 8–50 barns ƒ, fissile №, primarily a naturally occurring radioactive material (NORM) þ, neutron poison (thermal neutron capture cross section greater than 3k barns)

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.^[10]

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).^[11]^[12]

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.^[13]

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.^[14]

References

^ ^a ^b ^c ^d 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.
^ 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.
^ FRIB Nuclear Data Group. "Discovery of Nuclides Project, Isotope Database". doi:10.11578/frib/2279152.
^ FRIB Nuclear Data Group. "Discovery of Nuclides Project, Isomer Database". doi:10.11578/frib/2572219.
^ 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.
^ Specifically from thermal neutron fission of uranium-235, e.g. in a typical nuclear 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 of ²³²Th; e.g., while ^113mCd has a half-life of only fourteen years, that of ¹¹³Cd is eight quadrillion 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 from the original on 2018-06-16. Retrieved 2016-02-24.
^ 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. Bibcode:2000AppRI..53..785M. doi:10.1016/s0969-8043(00)00214-1. ISSN 0969-8043. PMID 11003521.
^ "Californium-252 & Antimony-Beryllium Sources". Frontier Technology Corp. Retrieved 2016-02-24.
^ 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.

Sources

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

[2] Cf – Excited nuclear isomer.

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

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

[8] Modes of decay:

EC: Electron capture

SF: Spontaneous fission

[9] ( ) spin value – Indicates spin with weak assignment arguments.

[TNN-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

[12] Half-life not measured, not included in discovery database

[13] High neutron cross-section, tends to absorb neutrons

[14] Most common isotope

[15] High neutron emitter, average 3.7 neutrons per fission

[16] Theoretically capable of β⁻β⁻ decay to ²⁵⁴Fm

[17] Theoretically capable of β⁻β⁻ decay to ²⁵⁶Fm or perhaps β⁻ decay to ²⁵⁶Es

[NUBASE2020-1] 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.

[AME2020_II-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.

[IsotopeFRIB-6] FRIB Nuclear Data Group. "Discovery of Nuclides Project, Isotope Database". doi:10.11578/frib/2279152.

[IsomerFRIB-7] FRIB Nuclear Data Group. "Discovery of Nuclides Project, Isomer Database". doi:10.11578/frib/2572219.

[18] 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.

[19] Specifically from thermal neutron fission of uranium-235, e.g. in a typical nuclear reactor.

[20] 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]."

[21] This is the heaviest nuclide with a half-life of at least four years before the "sea of instability".

[22] 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.

[252Cf-Dicello-23] 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.

[252Cf-frontier-cf252-24] "Portable Isotopic Neutron Spectroscopy (PINS) for the Military". Frontier Technology Corp. Archived from the original on 2018-06-16. Retrieved 2016-02-24.

[252Cf-Martin-25] 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. Bibcode:2000AppRI..53..785M. doi:10.1016/s0969-8043(00)00214-1. ISSN 0969-8043. PMID 11003521.

[252Cf-frontier-cf252b-26] "Californium-252 & Antimony-Beryllium Sources". Frontier Technology Corp. Retrieved 2016-02-24.

[252Cf-Maruyama-27] 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.

[1]

[n 1]

[2]

[n 2]

[n 3]

[3]

[4]

[n 4]

[n 5]

[n 6]

[n 7]

[n 8]

[n 9]

[n 10]

[n 11]

[n 12]

[n 13]

[5]

[6]

[7]

[8]

[9]

[10]

[11]

[12]

[13]

[14]

EC:	Electron capture
SF:	Spontaneous fission