Isotopes of californium

Actinides				Half-life	Fission products
244Cm	241Pu f	250Cf	243Cmf	10–30 y	137Cs	90Sr	85Kr
232U  f		238Pu	f is for fissile	69–90 y			151Sm nc➔
4n	249Cf  f	242Amf		141–351	No fission product has half-life 102 to 2×105 years
	241Am		251Cf  f	431–898
240Pu	229Th	246Cm	243Am	5–7 ky
4n	245Cmf	250Cm	239Pu f	8–24 ky
	233U    f	230Th	231Pa	32–160
	4n+1	234U	4n+3	211–290	99Tc		126Sn	79Se
248Cm		242Pu		340–373	Long-lived fission products
	237Np	4n+2		1–2 My	93Zr	135Cs nc➔
236U	4n+1		247Cmf	6–23 My		107Pd	129I
244Pu				80 My	>7%	>5%	>1%	>.1%
232Th		238U	235U    f	0.7–12 Gy	fission product yield

Californium (Cf) is a chemical element that is mainly produced synthetically, but trace quantities are found in nature from neutron capture by uranium atoms.

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.

Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life	decay mode(s)	daughter isotope(s)	nuclear spin
	excitation energy
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+#
					β+ (rare)	239Bk
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-#
					α (25%)	237Cm
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+)
					α (14%)	239Cm
244Cf	98	146	244.066001(3)	19.4(6) min	α (99%)	240Cm	0+
					EC (1%)	244Bk
245Cf	98	147	245.068049(3)	45.0(15) min	β+ (64%)	245Bk	(5/2+)
					α (36%)	241Cm
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+)#
					α (.04%)	243Cm
248Cf	98	150	248.072185(6)	333.5(28) d	α (99.99%)	244Cm	0+
					SF (.0029%)	(various)
249Cf	98	151	249.0748535(24)	351(2) a	α	245Cm	9/2-
					SF (5×10−7%)	(various)
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+
					SF (.077%)	(various)
251Cf	98	153	251.079587(5)	900(40) a	α	247Cm	1/2+
252Cf	98	154	252.081626(5)	2.645(8) a	α (96.9%)	248Cm	0+
					SF (3.09%)	(various)
253Cf	98	155	253.085133(7)	17.81(8) d	β- (99.69%)	253Es	(7/2+)
					α (.31%)	249Cm
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

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". Nuclear Physics A 729: 3–128. Bibcode 2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001. http://www.nndc.bnl.gov/amdc/nubase/Nubase2003.pdf. 
• 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. http://www.iupac.org/publications/pac/75/6/0683/pdf/. 
  • 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. http://iupac.org/publications/pac/78/11/2051/pdf/. Lay summary. 
• 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". Nuclear Physics A 729: 3–128. Bibcode 2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001. http://www.nndc.bnl.gov/amdc/nubase/Nubase2003.pdf. 
  • National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. http://www.nndc.bnl.gov/nudat2/. Retrieved September 2005. 
  • N. E. Holden (2004). "Table of the Isotopes". In D. R. Lide. CRC Handbook of Chemistry and Physics (85th ed.). CRC Press. Section 11. ISBN 978-0849304859. 
• Other

Isotopes of berkelium	Isotopes of californium	Isotopes of einsteinium
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