Isotopes of berkelium

Main isotopes of berkelium (₉₇Bk)
α	241Am
ε	246Cm
SF	–
β−	249Cf

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.

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]
Nuclide [n 1]	Excitation energy[n 6]			Half-life	Decay mode [n 4]	Daughter isotope	Spin and parity [n 5][n 6]
²³³Bk[2]	97	136		21 s	α	²²⁹Am
²³⁴Bk[3]	97	137		19(+6-4) s	α (50%)	²³⁰Am
²³⁴Bk[3]	97	137		19(+6-4) s	β⁺ (50%)	²³⁴Cm
²³⁶Bk	97	139	236.05733(43)#	22(+13-6) s[4]	α	²³²Am
²³⁶Bk	97	139	236.05733(43)#	22(+13-6) s[4]	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+)
²⁴¹Bk	97	144	241.06023(22)#	4.6(4) min	β⁺ (rare)	²⁴¹Cm	(7/2+)
²⁴²Bk	97	145	242.06198(22)#	7.0(13) min	β⁺ (99.99%)	²⁴²Cm	2−#
²⁴²Bk	97	145	242.06198(22)#	7.0(13) min	β⁺, SF (3×10⁻⁴%)	(various)	2−#
^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−)
²⁴³Bk	97	146	243.063008(5)	4.5(2) h	α (.15%)	²³⁹Am	(3/2−)
²⁴⁴Bk	97	147	244.065181(16)	4.35(15) h	β⁺ (99.99%)	²⁴⁴Cm	(4−)#
²⁴⁴Bk	97	147	244.065181(16)	4.35(15) h	α (.006%)	²⁴⁰Am	(4−)#
²⁴⁵Bk	97	148	245.0663616(25)	4.94(3) d	EC (99.88%)	²⁴⁵Cm	3/2−
²⁴⁵Bk	97	148	245.0663616(25)	4.94(3) d	α (.12%)	²⁴¹Am	3/2−
²⁴⁶Bk	97	149	246.06867(6)	1.80(2) d	β⁺ (99.8%)	²⁴⁶Cm	2(−)
²⁴⁶Bk	97	149	246.06867(6)	1.80(2) d	α (.2%)	²⁴²Am	2(−)
²⁴⁷Bk	97	150	247.070307(6)	1.38(25)×10³ y	α	²⁴³Am	(3/2−)
²⁴⁷Bk	97	150	247.070307(6)	1.38(25)×10³ y	SF (rare)	(various)	(3/2−)
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−)#
²⁵¹Bk	97	154	251.080760(12)	55.6(11) min	α (10⁻⁵%)	²⁴⁷Am	(3/2−)#
^251mBk	35.5(13) keV			58(4) µs	IT	²⁵¹Bk	(7/2+)#
²⁵²Bk	97	155	252.08431(22)#	1.8(5) min	β⁻	²⁵²Cf
²⁵²Bk	97	155	252.08431(22)#	1.8(5) min	α	²⁴⁸Am
²⁵³Bk	97	156	253.08688(39)#	10# min	β⁻	²⁵³Cf

^mBk – Excited nuclear isomer.
( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
# – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
Modes of decay:

EC: Electron capture

SF: Spontaneous fission
( ) spin value – Indicates spin with weak assignment arguments.
# – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
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		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	†		¹⁵⁵Eu^þ
²⁴⁴Cm^ƒ	²⁴¹Pu^ƒ	²⁵⁰Cf	²²⁷Ac^№	10–29 a		⁹⁰Sr	⁸⁵Kr	^113mCd^þ
²³²U^ƒ		²³⁸Pu^ƒ	²⁴³Cm^ƒ	29–97 a		¹³⁷Cs	¹⁵¹Sm^þ	^121mSn
²⁴⁸Bk[8]	²⁴⁹Cf^ƒ	^242mAm^ƒ		141–351 a	No fission products have a half-life in the range of 100–210 ka ...
	²⁴¹Am^ƒ		²⁵¹Cf^ƒ[9]	430–900 a
		²²⁶Ra^№	²⁴⁷Bk	1.3–1.6 ka
²⁴⁰Pu	²²⁹Th	²⁴⁶Cm^ƒ	²⁴³Am^ƒ	4.7–7.4 ka
	²⁴⁵Cm^ƒ	²⁵⁰Cm		8.3–8.5 ka
			²³⁹Pu^ƒ	24.1 ka
		²³⁰Th^№	²³¹Pa^№	32–76 ka
²³⁶Np^ƒ	²³³U^ƒ	²³⁴U^№		150–250 ka	‡	⁹⁹Tc^₡	¹²⁶Sn
²⁴⁸Cm		²⁴²Pu		327–375 ka			⁷⁹Se^₡
				1.53 Ma		⁹³Zr
	²³⁷Np^ƒ			2.1–6.5 Ma		¹³⁵Cs^₡	¹⁰⁷Pd
²³⁶U			²⁴⁷Cm^ƒ	15–24 Ma			¹²⁹I^₡
²⁴⁴Pu				80 Ma	... nor beyond 15.7 Ma[10]
²³²Th^№		²³⁸U^№	²³⁵U^ƒ№	0.7–14.1 Ga	... nor beyond 15.7 Ma[10]
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

References

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.
"Observation of new neutron-deficient isotopes with Z ≥ 92 in multinucleon transfer reactions" http://inspirehep.net/record/1383747/files/scoap3-fulltext.pdf
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.
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.
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.
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.
Specifically from thermal neutron fission of U-235, e.g. in a typical nuclear reactor.
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]."
This is the heaviest nuclide with a half-life of at least four years before the "Sea of Instability".
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.

Isotope masses from:
- Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
Isotopic compositions and standard atomic masses from:
- de Laeter, John Robert; Böhlke, John Karl; De Bièvre, Paul; Hidaka, Hiroshi; Peiser, H. Steffen; Rosman, Kevin J. R.; Taylor, Philip D. P. (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683.
- Wieser, Michael E. (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry. 78 (11): 2051–2066. doi:10.1351/pac200678112051. Lay summary.
Half-life, spin, and isomer data selected from the following sources.
- Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
- National Nuclear Data Center. "NuDat 2.x database". Brookhaven National Laboratory.
- Holden, Norman E. (2004). "11. Table of the Isotopes". In Lide, David R. (ed.). CRC Handbook of Chemistry and Physics (85th ed.). Boca Raton, Florida: CRC Press. ISBN 978-0-8493-0485-9.

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[2] Bk – Excited nuclear isomer.

[3] ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.

[TMS-4] # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).

[5] Modes of decay:

EC: Electron capture

SF: Spontaneous fission

[6] ( ) spin value – Indicates spin with weak assignment arguments.

[TNN-7] # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).

[12] Easiest isotope to synthesize

[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.

[8] "Observation of new neutron-deficient isotopes with Z ≥ 92 in multinucleon transfer reactions" http://inspirehep.net/record/1383747/files/scoap3-fulltext.pdf

[9] 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.

[Konki+17-10] 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.

[11] 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.

[13] 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.

[14] Specifically from thermal neutron fission of U-235, e.g. in a typical nuclear reactor.

[15] 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]."

[16] This is the heaviest nuclide with a half-life of at least four years before the "Sea of Instability".

[17] 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.

Isotopes of berkelium

List of isotopes

Actinides vs fission products

See also

References