Isotopes of berkelium

Berkelium (97Bk) 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 243Bk in 1949. There are 18 known radioisotopes, from 233Bk to 253Bk (with the exception of 235Bk, 237Bk, and 239Bk), and 6 nuclear isomers. The longest-lived isotope is 247Bk with a half-life of 1,380 years.

Main isotopes of berkelium (97Bk)
Iso­tope Decay
abun­dance half-life (t1/2) mode pro­duct
245Bk syn 4.94 d ε 245Cm
α 241Am
246Bk syn 1.8 d α 242Am
ε 246Cm
247Bk syn 1380 y α 243Am
248Bk syn >300 y[1] α 244Am
249Bk syn 330 d α 245Am
SF
β 249Cf

List of isotopes

Nuclide
[n 1]
Z N Isotopic mass (Da)
[n 2][n 3]
Half-life
Decay
mode

[n 4]
Daughter
isotope

Spin and
parity
[n 5][n 6]
Excitation energy[n 6]
233Bk[2] 97 136 21 s α 229Am
234Bk[3] 97 137 19(+6-4) s α (50%) 230Am
β+ (50%) 234Cm
236Bk 97 139 236.05733(43)# 22(+13-6) s[4] α 232Am
β+ 236Cm
238Bk 97 141 238.05828(31)# 2.40(8) min α 234Am
β+, SF (.048%) (various)
β+ (rare) 238Cm
240Bk 97 143 240.05976(16)# 4.8(8) min β+ (90%) 240Cm
α (10%) 236Am
β+, SF (.002%) (various)
241Bk 97 144 241.06023(22)# 4.6(4) min α 237Am (7/2+)
β+ (rare) 241Cm
242Bk 97 145 242.06198(22)# 7.0(13) min β+ (99.99%) 242Cm 2−#
β+, SF (3×10−4%) (various)
242mBk 200(200)# keV 600(100) ns SF (various)
243Bk 97 146 243.063008(5) 4.5(2) h β+ (99.85%) 243Cm (3/2−)
α (.15%) 239Am
244Bk 97 147 244.065181(16) 4.35(15) h β+ (99.99%) 244Cm (4−)#
α (.006%) 240Am
245Bk 97 148 245.0663616(25) 4.94(3) d EC (99.88%) 245Cm 3/2−
α (.12%) 241Am
246Bk 97 149 246.06867(6) 1.80(2) d β+ (99.8%) 246Cm 2(−)
α (.2%) 242Am
247Bk 97 150 247.070307(6) 1.38(25)×103 y α 243Am (3/2−)
SF (rare) (various)
248Bk 97 151 248.07309(8)# >300 y[5] α 244Am 6+#
248mBk 30(70)# keV 23.7(2) h β 248Cf 1(−)
249Bk[n 7] 97 152 249.0749867(28) 330(4) d β 249Cf 7/2+
α (.00145%) 245Am
SF (4.7×10−8%) (various)
249mBk 8.80(10) keV 300 µs IT 249Bk (3/2−)
250Bk 97 153 250.078317(4) 3.212(5) h β 250Cf 2−
250m1Bk 35.59(5) keV 29(1) µs IT 250Bk (4+)
250m2Bk 84.1(21) keV 213(8) µs (7+)
251Bk 97 154 251.080760(12) 55.6(11) min β 251Cf (3/2−)#
α (10−5%) 247Am
251mBk 35.5(13) keV 58(4) µs IT 251Bk (7/2+)#
252Bk 97 155 252.08431(22)# 1.8(5) min β 252Cf
α 248Am
253Bk 97 156 253.08688(39)# 10# min β 253Cf
  1. mBk  Excited nuclear isomer.
  2. ()  Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
  3. #  Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
  4. Modes of decay:
    EC:Electron capture
    SF:Spontaneous fission
  5. () spin value  Indicates spin with weak assignment arguments.
  6. #  Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
  7. Easiest isotope to synthesize

Actinides vs fission products

Actinides and fission products by half-life
Actinides[6] by decay chain Half-life
range (a)
Fission products of 235U by yield[7]
4n 4n+1 4n+2 4n+3
4.5–7% 0.04–1.25% <0.001%
228Ra 4–6 a 155Euþ
244Cmƒ 241Puƒ 250Cf 227Ac 10–29 a 90Sr 85Kr 113mCdþ
232Uƒ 238Puƒ 243Cmƒ 29–97 a 137Cs 151Smþ 121mSn
248Bk[8] 249Cfƒ 242mAmƒ 141–351 a

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

241Amƒ 251Cfƒ[9] 430–900 a
226Ra 247Bk 1.3–1.6 ka
240Pu 229Th 246Cmƒ 243Amƒ 4.7–7.4 ka
245Cmƒ 250Cm 8.3–8.5 ka
239Puƒ 24.1 ka
230Th 231Pa 32–76 ka
236Npƒ 233Uƒ 234U 150–250 ka 99Tc 126Sn
248Cm 242Pu 327–375 ka 79Se
1.53 Ma 93Zr
237Npƒ 2.1–6.5 Ma 135Cs 107Pd
236U 247Cmƒ 15–24 Ma 129I
244Pu 80 Ma

... nor beyond 15.7 Ma[10]

232Th 238U 235Uƒ№ 0.7–14.1 Ga

Legend for superscript symbols
  has thermal neutron capture cross section in the range of 8–50 barns
ƒ  fissile
m  metastable isomer
  primarily a naturally occurring radioactive material (NORM)
þ  neutron poison (thermal neutron capture cross section greater than 3k barns)
  range 4–97 a: Medium-lived fission product
  over 200 ka: Long-lived fission product

See also

References

  1. Milsted, J.; Friedman, A. M.; Stevens, C. M. (1965). "The alpha half-life of berkelium-247; a new long-lived isomer of berkelium-248". Nuclear Physics. 71 (2): 299. doi:10.1016/0029-5582(65)90719-4.
  2. "Observation of new neutron-deficient isotopes with Z ≥ 92 in multinucleon transfer reactions" http://inspirehep.net/record/1383747/files/scoap3-fulltext.pdf
  3. Kaji, D.; Morimoto, K.; Haba, H.; Ideguchi, E.; Koura, H.; Morita, K. (2016). "Decay Properties of New Isotopes 234Bk and 230Am, and Even–Even Nuclides 234Cm and 230Pu" (PDF). Journal of the Physical Society of Japan. 84 (15002): 015002. doi:10.7566/JPSJ.85.015002.
  4. Konki, J.; et al. (10 Jan 2017). "Towards saturation of the electron-capture delayed fission probability: The new isotopes 240Es and 236Bk". Physics Letters B. 764: 265–270. Bibcode:2017PhLB..764..265K. doi:10.1016/j.physletb.2016.11.038. ISSN 0370-2693.
  5. Milsted, J.; Friedman, A. M.; Stevens, C. M. (1965). "The alpha half-life of berkelium-247; a new long-lived isomer of berkelium-248". Nuclear Physics. 71 (2): 299. Bibcode:1965NucPh..71..299M. doi:10.1016/0029-5582(65)90719-4.
  6. Plus radium (element 88). While actually a sub-actinide, it immediately precedes actinium (89) and follows a three-element gap of instability after polonium (84) where no nuclides have half-lives of at least four years (the longest-lived nuclide in the gap is radon-222 with a half life of less than four days). Radium's longest lived isotope, at 1,600 years, thus merits the element's inclusion here.
  7. Specifically from thermal neutron fission of U-235, e.g. in a typical nuclear reactor.
  8. Milsted, J.; Friedman, A. M.; Stevens, C. M. (1965). "The alpha half-life of berkelium-247; a new long-lived isomer of berkelium-248". Nuclear Physics. 71 (2): 299. Bibcode:1965NucPh..71..299M. doi:10.1016/0029-5582(65)90719-4.
    "The isotopic analyses disclosed a species of mass 248 in constant abundance in three samples analysed over a period of about 10 months. This was ascribed to an isomer of Bk248 with a half-life greater than 9 [years]. No growth of Cf248 was detected, and a lower limit for the β half-life can be set at about 104 [years]. No alpha activity attributable to the new isomer has been detected; the alpha half-life is probably greater than 300 [years]."
  9. This is the heaviest nuclide with a half-life of at least four years before the "Sea of Instability".
  10. Excluding those "classically stable" nuclides with half-lives significantly in excess of 232Th; e.g., while 113mCd has a half-life of only fourteen years, that of 113Cd is nearly eight quadrillion years.
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.