Isotopes of berkelium

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Isotopes of berkelium  (97Bk)
Main isotopes [1] Decay
abun­dance half-life (t1/2) mode pro­duct
245Bk synth 4.94 d ε 245Cm
α 241Am
246Bksynth1.8 dα 242Am
β+ 246Cm
247Bksynth1380 yα 243Am
248Bksynth>9 y [2] α 244Am
249Bksynth330 d β− 249Cf
α 245Am
SF –

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 twenty known radioisotopes, from 233Bk and 233Bk to 253Bk (except 235Bk and 237Bk), and six nuclear isomers. The longest-lived isotope is 247Bk with a half-life of 1,380 years.

Contents

List of isotopes


Nuclide
[n 1] 		Z N Isotopic mass (Da) [3]
[n 2] [n 3] 		Half-life [1]
Decay
mode [1]
[n 4] 		Daughter
isotope
Spin and
parity [1]
[n 5] [n 6]
Excitation energy [n 6]
233Bk97136233.05665(25)#40(30) s α 229Am3/2-#
β+?233Cm
234Bk97137234.05732(16)#20(5) sα (>80%)230Am3-#
β+ (<20%)234Cm
β+, SF? [4] (various)
236Bk97139236.05748(39)#26(10) sβ+ (99.96%)236Cm4+#
β+, SF (0.04%)(various)
α?232Am
238Bk97141238.05820(28)#2.40(8) minβ+ (99.95%)238Cm1#
β+, SF (0.048%)(various)
α?234Am
239Bk97142239.05824(22)#100# sβ+239Cm(7/2+)
α?235Am
SF?(various)
240Bk97143240.05976(16)#4.8(8) minβ+?240Cm7−#
β+, SF (0.0020%)(various)
α?236Am
241Bk97144241.06010(18)#4.6(4) minβ+?241Cm(7/2+)
α?237Am
242Bk97145242.06198(22)#7.0(13) minβ+242Cm3+#
β+, SF (<3×10−5%)(various)
α?238Am
242mBk2000(200)# keV600(100) nsSF(various)
IT?242Bk
243Bk97146243.0630059(49)4.6(2) hβ+ (99.85%)243Cm3/2−
α (.15%)239Am
244Bk97147244.065179(15)5.02(3) hβ+?244Cm4−
α (0.006%)240Am
244mBk1500(500)# keV820(60) nsSF(various)
IT?244Bk
245Bk97148245.0663598(19)4.95(3) d EC (99.88%)245Cm3/2−
α (.12%)241Am
246Bk97149246.068671(64)1.80(2) dβ+246Cm2(−)
α?242Am
247Bk97150247.0703059(56)1.38(25)×103 yα243Am3/2−
SF?(various)
248Bk97151248.073142(54)>9 yα?244Am6+#
EC?248Cm
248mBk−20(50) keV [n 7] 23.7(2) hβ− (70%)248Cf1(−)
EC (30%)248Cm
α?244Am
249Bk97152249.0749831(13)327.2(3) dβ−249Cf7/2+
α (.00145%)245Am
SF (4.7×10−8%)(various)
249mBk8.777(14) keV300 μsIT249Bk3/2−
250Bk97153250.0783172(31)3.212(5) hβ−250Cf2−
250m1Bk35.59(10) keV29(1) μsIT250Bk4+
250m2Bk85.6(16) keV213(8) μsIT250Bk7+
251Bk97154251.080761(12)55.6(11) minβ−251Cf(3/2−)
251mBk35.5(13) keV58(4) μsIT251Bk(7/2+)
252Bk97155252.08431(22)#1.8(5) minβ−?252Cf
α?248Am
253Bk97156253.08688(39)#60# minβ−?253Cf3/2-#
This table header & footer:
  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. 1 2 # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
  7. ↑ Order of ground state and isomer is uncertain. [1] [5]

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%
228 Ra№ 4–6 a 155 Euþ
248 Bk [8] > 9 a
244 Cmƒ 241 Puƒ 250 Cf 227 Ac№ 10–29 a 90 Sr 85 Kr 113m Cdþ
232 Uƒ 238 Puƒ 243 Cmƒ 29–97 a 137 Cs 151 Smþ 121m Sn
249 Cfƒ 242m Amƒ141–351 a

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

241 Amƒ 251 Cfƒ [9] 430–900 a
226 Ra№ 247 Bk1.3–1.6 ka
240 Pu 229 Th 246 Cmƒ 243 Amƒ4.7–7.4 ka
245 Cmƒ 250 Cm8.3–8.5 ka
239 Puƒ24.1 ka
230 Th№ 231 Pa№32–76 ka
236 Npƒ 233 Uƒ 234 U№ 150–250 ka 99 Tc₡ 126 Sn
248 Cm 242 Pu 327–375 ka 79 Se₡
1.33 Ma 135 Cs₡
237 Npƒ 1.61–6.5 Ma 93 Zr 107 Pd
236 U 247 Cmƒ 15–24 Ma 129 I₡
244 Pu80 Ma

... nor beyond 15.7 Ma [10]

232 Th№ 238 U№ 235 Uƒ№0.7–14.1 Ga

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References

  1. 1 2 3 4 5 Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
  2. ↑ 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.
  3. ↑ Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*". Chinese Physics C. 45 (3): 030003. doi:10.1088/1674-1137/abddaf.
  4. ↑ 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. Bibcode:2016JPSJ...85a5002K. doi:10.7566/JPSJ.85.015002.
  5. ↑ "Adopted Levels for 248Bk". NNDC Chart of Nuclides.
  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 uranium-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 eight quadrillion years.
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