Californium-249

Main isotopes of californium

iso NA half-life DM DE (MeV) DP 248Cf syn 333.5 d α (100%) 6.369 244Cm SF (2.9×10−3%) 0.0029 – 249Cf syn 351 y α (100%) 6.295 245Cm SF (5.0×10−7%) 4.4×10−7 – 250Cf syn 13.08 y α (99.92%) 6.129 246Cm SF (0.08%) 0.077 – 251Cf syn 898 y α 6.172 247Cm 252Cf syn 2.645 y α (96.91%) 6.217 248Cm SF (3.09%) – – 253Cf syn 17.81 d β− (99.69%) 0.29 253Es α (0.31%) 6.126 249Cm 254Cf syn 60.5 d SF (99.69%) – – α (0.31%) 5.930 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 one nuclear isomer, ^249mCf. The longest-lived isotope is ²⁵¹Cf with a half-life of 900 years.

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

... nor beyond 15.7 M years

Legend for superscript symbols
₡  has thermal neutron capture cross section in the range of 8–50 barns
ƒ  fissile
m  metastable isomer
№  naturally occurring radioactive material (NORM)
þ  neutron poison (thermal neutron capture cross section greater than 3k barns)
†  range 4–97 y: Medium-lived fission product
‡  over 200,000 y: Long-lived fission product

Californium-252 (Cf-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.

This isotope produces high neutron emissions and can be used for a number of applications in industries such as nuclear energy, medicine, and petrochemical exploration.

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Wikipedia