World Library  
Flag as Inappropriate
Email this Article


Article Id: WHEBN0012653650
Reproduction Date:

Title: Californium-252  
Author: World Heritage Encyclopedia
Language: English
Subject: Decay chain, Cobalt-60, List of alpha emitting materials
Publisher: World Heritage Encyclopedia


Actinides and fission products by half-life
Actinides[1] by decay chain Half-life
range (a)
Fission products by yield[2]
4n 4n+1 4n+2 4n+3
4.5–7% 0.04–1.25% <0.001%
228Ra 4–6 155Euþ
244Cm 241Puƒ 250Cf 227Ac 10–29 90Sr 85Kr 113mCdþ
232Uƒ 238Pu 243Cmƒ 29–97 137Cs 151Smþ 121mSn
249Cfƒ 242mAmƒ 141–351

No fission products
have a half-life
in the range of
100–210k years…

241Am 251Cfƒ[3] 430–900
226Ra 247Bk 1.3k–1.6k
240Pu 229Th 246Cm 243Am 4.7k–7.4k
245Cmƒ 250Cm 8.3k–8.5k
239Puƒ 24.1k
230Th 231Pa 32k–76k
236Npƒ 233Uƒ 234U 150k–250k 99Tc 126Sn
248Cm 242Pu 327k–375k 79Se
1.53M 93Zr
237Np 2.1M–6.5M 135Cs 107Pd
236U 247Cmƒ 15M–24M 129I
244Pu 80M

...nor beyond 15.7M[4]

232Th 238U 235Uƒ№ 0.7G–14G

Legend for superscript symbols
₡  has thermal neutron capture cross section in the range of 8–50 barns
ƒ  fissile
metastable isomer
№  naturally occurring radioactive material (NORM)
þ  neutron poison (thermal neutron capture cross section greater than 3k barns)
†  range 4a–97a: Medium-lived fission product
‡  over 200ka: Long-lived fission product

Californium (Cf) is a chemical element that is mainly produced synthetically, but trace quantities are found in nature from neutron capture by uranium atoms.[5]

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 undergoes spontaneous fission and is used in small sized 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.[6]


Z(p) N(n)  
isotopic mass (u)
half-life decay
mode(s)[7][n 1]
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[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+
SF (3.09%)[n 4] (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


  • 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.


  • Isotope masses from:
  • Isotopic compositions and standard atomic masses from:
  • Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.
  • Other
Isotopes of berkelium Isotopes of californium Isotopes of einsteinium
Table of nuclides
he:קליפורניום#איזוטופים של קליפורניום
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.