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词条 Isotopes of californium
释义

  1. Actinides vs fission products

  2. Californium-252

      Uses    Nuclear reactors    Military and defense    Oil and petroleum    Medicine  

  3. List of isotopes

      Notes  

  4. References

{{infobox californium isotopes}}

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.

Actinides vs fission products

{{Actinidesvsfissionproducts}}{{clear}}

Californium-252

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.[1]

Uses

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.

Nuclear reactors

The neutron sources produced from Cf-252 are most notably used in the start-up of nuclear reactors. Once a reactor is filled with nuclear fuel, the stable neutron emissions from the source material initiates the fission chain reaction.

Military and defense

The portable isotopic neutron spectroscopy (PINS) used by United States Armed Forces, the National Guard, Homeland Security, and U.S. Customs and Border Protection, employs the use of Cf-252 sources to detect hazardous contents found inside artillery projectiles, mortar projectiles, rockets, bombs, land mines, and improvised explosive devices (IED).[2][3]

Oil and petroleum

In the oil industry, Cf-252 neutron sources are 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.[4]

Medicine

Californium-252 has also been used in the treatment of serious forms of cancer. In patients suffering from certain types of brain and cervical cancer, Cf-252 can be used as a more cost-effective substitute for radium.[5]

List of isotopes

nuclide
symbol		 Z(p) N(n)  
isotopic mass (u)
 		half-lifedecay
mode(s)[6][7]		daughter
isotope(s)		nuclear
spin and
parity
excitation energy
237Cf98139237.06207(54)#2.1(3) s SF (various)5/2+#
β+ 237Bk
α 233Cm
238Cf98140238.06141(43)#21.1(13) ms SF [8] (various)0+
β+ (rare) 238Bk
α (rare) 234Cm
239Cf98141239.06242(23)#60(30) s
[39(+37−12) s]		 α 235Cm5/2+#
β+ (rare) 239Bk
240Cf98142240.06230(22)#1.06(15) min α (98%) 236Cm0+
SF (2%) (various)
β+ (rare) 240Bk
241Cf98143241.06373(27)#3.78(70) min β+ (75%) 241Bk7/2−#
α (25%) 237Cm
242Cf98144242.06370(4)3.49(15) min α (80%) 238Cm0+
β+ (20%) 242Bk
SF (.014%) (various)
243Cf98145243.06543(15)#10.7(5) min β+ (86%) 243Bk(1/2+)
α (14%) 239Cm
244Cf98146244.066001(3)19.4(6) min α (99%) 240Cm0+
EC (1%) 244Bk
245Cf98147245.068049(3)45.0(15) min β+ (64%) 245Bk(5/2+)
α (36%) 241Cm
246Cf98148246.0688053(22)35.7(5) h α 242Cm0+
EC (5×10−4%) 246Bk
SF (2×10−4%) (various)
247Cf98149247.071001(9)3.11(3) h EC (99.96%) 247Bk(7/2+)#
α (.04%) 243Cm
248Cf98150248.072185(6)333.5(28) d α (99.99%) 244Cm0+
SF (.0029%) (various)
249Cf98151249.0748535(24)351(2) y α 245Cm9/2−
SF (5×10−7%) (various)
249mCf144.98(5) keV 45(5) µs 5/2+
250Cf98152250.0764061(22)13.08(9) y α (99.92%) 246Cm0+
SF (.077%) (various)
251Cf[9]98153 251.079587(5) 900(40) y α 247Cm 1/2+
252Cf[10]98154252.081626(5)2.645(8) y α (96.9%) 248Cm0+
SF (3.09%)[11] (various)
253Cf98155253.085133(7)17.81(8) d β− (99.69%) 253Es(7/2+)
α (.31%) 249Cm
254Cf98156254.087323(13)60.5(2) d SF (99.69%) (various)0+
α (.31%) 250Cm
β−β− (rare) 254Fm
255Cf98157255.09105(22)#85(18) min β− (99.99%) 255Es(7/2+)
SF (.001%) (various)
α (10−5%) 251Cm
256Cf98158256.09344(32)#12.3(12) min SF (~100%) (various)0+
α (10−6%) 252Cm
β−β− (rare) 256Fm
1. ^{{cite journal|title = Radiation Quality of Californium-252|journal = Physics in Medicine and Biology|first = J. F.|last = Dicello |last2=Gross |first2=W. |last3=Kraljevic |first3=U. |year = 1972 |doi= 10.1088/0031-9155/17/3/301 |page = 345 |volume=17 |issue= 3 |bibcode = 1972PMB....17..345D }}
2. ^{{Cite web|title = Portable Isotopic Neutron Spectroscopy (PINS) for the Military|url = http://www.frontier-cf252.com/portable-isotopic-neutron-spectroscopy-military.html|website = Frontier Technology Corp.|access-date = 2016-02-24}}
3. ^{{Cite journal|title = Production, distribution and applications of californium-252 neutron sources|journal = Applied Radiation and Isotopes: Including Data, Instrumentation and Methods for Use in Agriculture, Industry and Medicine|date = 2000-11-01|issn = 0969-8043|pmid = 11003521|pages = 785–792|volume = 53|issue = 4–5|first = R. C.|last = Martin|first2 = J. B.|last2 = Knauer|first3 = P. A.|last3 = Balo|doi=10.1016/s0969-8043(00)00214-1}}
4. ^{{Cite web|title = Californium-252 & Antimony-Beryllium Sources|url = http://www.frontier-cf252.com|website = Frontier Technology Corp.|access-date = 2016-02-24}}
5. ^{{Cite journal|title = Five-year cure of cervical cancer treated using californium-252 neutron brachytherapy|journal = American Journal of Clinical Oncology|date = 1984-10-01|issn = 0277-3732|pmid = 6391143|pages = 487–493|volume = 7|issue = 5|first = Y.|last = Maruyama|first2 = J. R.|last2 = van Nagell|first3 = J.|last3 = Yoneda|first4 = E.|last4 = Donaldson|first5 = M.|last5 = Hanson|first6 = A.|last6 = Martin|first7 = L. C.|last7 = Wilson|first8 = C. W.|last8 = Coffey|first9 = J.|last9 = Feola|doi=10.1097/00000421-198410000-00018}}
6. ^{{cite web |url=http://www.nucleonica.net/unc.aspx |title=Universal Nuclide Chart |publisher=nucleonica |registration=yes}}
7. ^Abbreviations:
EC: Electron capture
SF: Spontaneous fission
8. ^Lightest nuclide known to undergo spontaneous fission as the main decay mode
9. ^High neutron cross-section, tends to absorb neutrons
10. ^Most common isotope
11. ^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:
    • {{NUBASE 2003}}
  • Isotopic compositions and standard atomic masses from:
    • {{CAWIA 2003}}
    • {{CIAAW 2005}}
  • Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.
    • {{NUBASE 2003}}
    • {{NNDC}}
    • {{CRC85|chapter=11}}
  • Other
{{Navbox element isotopes}}קליפורניום#איזוטופים של קליפורניום

3 : Californium|Isotopes of californium|Lists of isotopes by element
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