Isotopes of californium

Actinides and fission products by half-life v t e
Actinides^[1] by decay chain				Half-life range (a)	Fission products of ²³⁵U by yield^[2]
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^[3]				> 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^[4]	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^[5]
²³²Th^№		²³⁸U^№	²³⁵U^ƒ№	0.7–14.1 Ga	... nor beyond 15.7 Ma^[5]
₡, 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 (Cf) is an artificial element, and thus a standard atomic mass 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 900 years.

Californium-252

Fission neutrons of californium-252 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.^[6]

Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life	decay mode(s)^[7]^{[n 1]}	daughter isotope(s)	nuclear spin
nuclide symbol	excitation energy			half-life	decay mode(s)^[7]^{[n 1]}	daughter isotope(s)	nuclear spin
²³⁷Cf	98	139	237.06207(54)#	2.1(3) s	SF	(various)	5/2+#
					β⁺	²³⁷Bk
					α	²³³Cm
²³⁸Cf	98	140	238.06141(43)#	21.1(13) ms	SF	(various)	0+
					β⁺ (rare)	²³⁸Bk
					α (rare)	²³⁴Cm
²³⁹Cf	98	141	239.06242(23)#	60(30) s [39(+37-12) s]	α	²³⁵Cm	5/2+#
²³⁹Cf	98	141	239.06242(23)#	60(30) s [39(+37-12) s]	β⁺ (rare)	²³⁹Bk	5/2+#
²⁴⁰Cf	98	142	240.06230(22)#	1.06(15) min	α (98%)	²³⁶Cm	0+
					SF (2%)	(various)
					β⁺ (rare)	²⁴⁰Bk
²⁴¹Cf	98	143	241.06373(27)#	3.78(70) min	β⁺ (75%)	²⁴¹Bk	7/2-#
²⁴¹Cf	98	143	241.06373(27)#	3.78(70) min	α (25%)	²³⁷Cm	7/2-#
²⁴²Cf	98	144	242.06370(4)	3.49(15) min	α (80%)	²³⁸Cm	0+
					β⁺ (20%)	²⁴²Bk
					SF (.014%)	(various)
²⁴³Cf	98	145	243.06543(15)#	10.7(5) min	β⁺ (86%)	²⁴³Bk	(1/2+)
²⁴³Cf	98	145	243.06543(15)#	10.7(5) min	α (14%)	²³⁹Cm	(1/2+)
²⁴⁴Cf	98	146	244.066001(3)	19.4(6) min	α (99%)	²⁴⁰Cm	0+
²⁴⁴Cf	98	146	244.066001(3)	19.4(6) min	EC (1%)	²⁴⁴Bk	0+
²⁴⁵Cf	98	147	245.068049(3)	45.0(15) min	β⁺ (64%)	²⁴⁵Bk	(5/2+)
²⁴⁵Cf	98	147	245.068049(3)	45.0(15) min	α (36%)	²⁴¹Cm	(5/2+)
²⁴⁶Cf	98	148	246.0688053(22)	35.7(5) h	α	²⁴²Cm	0+
					EC (5×10⁻⁴%)	²⁴⁶Bk
					SF (2×10⁻⁴%)	(various)
²⁴⁷Cf	98	149	247.071001(9)	3.11(3) h	EC (99.96%)	²⁴⁷Bk	(7/2+)#
²⁴⁷Cf	98	149	247.071001(9)	3.11(3) h	α (.04%)	²⁴³Cm	(7/2+)#
²⁴⁸Cf	98	150	248.072185(6)	333.5(28) d	α (99.99%)	²⁴⁴Cm	0+
²⁴⁸Cf	98	150	248.072185(6)	333.5(28) d	SF (.0029%)	(various)	0+
²⁴⁹Cf	98	151	249.0748535(24)	351(2) a	α	²⁴⁵Cm	9/2-
²⁴⁹Cf	98	151	249.0748535(24)	351(2) a	SF (5×10⁻⁷%)	(various)	9/2-
^249mCf	144.98(5) keV			45(5) µs			5/2+
²⁵⁰Cf	98	152	250.0764061(22)	13.08(9) a	α (99.92%)	²⁴⁶Cm	0+
²⁵⁰Cf	98	152	250.0764061(22)	13.08(9) a	SF (.077%)	(various)	0+
²⁵¹Cf^{[n 2]}	98	153	251.079587(5)	900(40) a	α	²⁴⁷Cm	1/2+
²⁵²Cf^{[n 3]}	98	154	252.081626(5)	2.645(8) a	α (96.9%)	²⁴⁸Cm	0+
²⁵²Cf^{[n 3]}	98	154	252.081626(5)	2.645(8) a	SF (3.09%)^{[n 4]}	(various)	0+
²⁵³Cf	98	155	253.085133(7)	17.81(8) d	β^- (99.69%)	²⁵³Es	(7/2+)
²⁵³Cf	98	155	253.085133(7)	17.81(8) d	α (.31%)	²⁴⁹Cm	(7/2+)
²⁵⁴Cf	98	156	254.087323(13)	60.5(2) d	SF (99.69%)	(various)	0+
					α (.31%)	²⁵⁰Cm
					β^-β^- (rare)	²⁵⁴Fm
²⁵⁵Cf	98	157	255.09105(22)#	85(18) min	β^- (99.99%)	²⁵⁵Es	(7/2+)
					SF (.001%)	(various)
					α (10⁻⁵%)	²⁵¹Cm
²⁵⁶Cf	98	158	256.09344(32)#	12.3(12) min	SF (99%)	(various)	0+
					β^- (1%)	²⁵⁶Es
					α (10⁻⁶%)	²⁵²Cm
					β^-β^- (rare)	²⁵⁶Fm

^ Abbreviations:
EC: Electron capture
SF: Spontaneous fission
^ High neutron cross-section, tends to absorb neutrons
^ Most common isotope
^ High neutron emitter, average 3.7 neutrons per fission

Notes

Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC which use expanded uncertainties.

References

Isotope masses from:
- G. Audi, A. H. Wapstra, C. Thibault, J. Blachot and O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A. 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001.{{cite journal}}: CS1 maint: multiple names: authors list (link)
Isotopic compositions and standard atomic masses from:
- J. R. de Laeter, J. K. Böhlke, P. De Bièvre, H. Hidaka, H. S. Peiser, K. J. R. Rosman and P. D. P. Taylor (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683.{{cite journal}}: CS1 maint: multiple names: authors list (link)
- M. E. Wieser (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry. 78 (11): 2051–2066. doi:10.1351/pac200678112051. {{cite journal}}: Unknown parameter |laysummary= ignored (help)
Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.
- G. Audi, A. H. Wapstra, C. Thibault, J. Blachot and O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A. 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001.{{cite journal}}: CS1 maint: multiple names: authors list (link)
- National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. Retrieved September 2005. {{cite web}}: Check date values in: |accessdate= (help)
- N. E. Holden (2004). "Table of the Isotopes". In D. R. Lide (ed.). CRC Handbook of Chemistry and Physics (85th ed.). CRC Press. Section 11. ISBN 978-0849304859. {{cite book}}: Unknown parameter |nopp= ignored (|no-pp= suggested) (help)
Other

^ 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. (1972). "Radiation Quality of Californium-252". Physics in Medicine and Biology. 17 (3): 345. doi:10.1088/0031-9155/17/3/301. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
^ http://www.nucleonica.net/unc.aspx

[8] Abbreviations:
EC: Electron capture
SF: Spontaneous fission

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

[10] Most common isotope

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

[1] 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.

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

[3] 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]."

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

[5] 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.

[6] Dicello, J. F. (1972). "Radiation Quality of Californium-252". Physics in Medicine and Biology. 17 (3): 345. doi:10.1088/0031-9155/17/3/301. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[7] ttp://www.nucleonica.net/unc.aspx

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