Isotopes of californium

List of isotopes

More information Nuclide, Z ...

Nuclide ^{[n 1]}	Z	N	Isotopic mass (Da)^[2] ^{[n 2]}^{[n 3]}	Half-life^[1]	Decay mode^[1] ^{[n 4]}	Daughter isotope	Spin and parity^[1] ^{[n 5]}^{[n 6]}
Excitation energy
²³⁷Cf	98	139	237.06220(10)	0.8(2) s	α (70%)	²³³Cm	5/2+#
SF (30%)	(various)
²³⁸Cf	98	140	238.06149(32)#	21.1(13) ms	SF (97.5%)^{[n 7]}	(various)	0+
α (2.5%)	²³⁴Cm
²³⁹Cf	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)
²⁴¹Cf	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)
²⁴⁷Cf	98	149	247.070971(15)	3.11(3) h	EC (99.965%)	²⁴⁷Bk	(7/2+)
α (0.035%)	²⁴³Cm
²⁴⁸Cf	98	150	248.072183(5)	333.5(28) d	α	²⁴⁴Cm	0+
SF (0.0029%)	(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	²⁴⁹Cf	5/2+
²⁵⁰Cf	98	152	250.0764045(17)	13.08(9) y	α (99.923%)	²⁴⁶Cm	0+
SF (0.077%)	(various)
²⁵¹Cf^{[n 8]}	98	153	251.079587(4)	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	253.085134(5)	17.81(8) d	β⁻ (99.69%)	²⁵³Es	(7/2+)
α (0.31%)	²⁴⁹Cm
²⁵⁴Cf^{[n 11]}	98	156	254.087324(12)	60.5(2) d	SF (99.69%)	(various)	0+
α (0.31%)	²⁵⁰Cm
²⁵⁵Cf	98	157	255.09105(22)#	85(18) min	β⁻	²⁵⁵Es	(7/2+)
²⁵⁶Cf^{[n 12]}	98	158	256.09344(34)#	12.3(12) min	SF	(various)	0+
This table header & footer: view

[n 1]
^mCf – Excited nuclear isomer.
[n 2]
( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
[n 3]
# – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
[n 4]
Modes of decay:

EC: Electron capture

SF: Spontaneous fission
[n 5]
( ) spin value – Indicates spin with weak assignment arguments.
[n 6]
# – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
[n 7]
Lightest nuclide known to undergo spontaneous fission as its main decay mode
[n 8]
High neutron cross-section, tends to absorb neutrons
[n 9]
Most common isotope
[N 10]
High neutron emitter, average 3.7 neutrons per fission
[N 11]
Theoretically capable of β⁻β⁻ decay to ²⁵⁴Fm
[N 12]
Theoretically capable of β⁻β⁻ decay to ²⁵⁶Fm or perhaps β⁻ decay to ²⁵⁶Es

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Actinides vs fission products

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Perspective

More information Half-life range (a), 4n ...

Actinides and fission products by half-life v t e
Actinides^[3] by decay chain	Half-life range (a)	Fission products of ²³⁵U by yield^[4]
4n	4n + 1	4n + 2	4n + 3	4.5–7%	0.04–1.25%	<0.001%
²²⁸Ra^№				4–6 a		¹⁵⁵Eu^þ
²⁴⁸Bk^[5]				> 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^[6]	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^[7]
²³²Th^№		²³⁸U^№	²³⁵U^ƒ№	0.7–14.1 Ga
₡, 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)

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Californium-252

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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.^[8]

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).^[9]^[10]

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.^[11]

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.^[12]