Isotopes of protactinium: Difference between revisions

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Actinides and fission products by half-life v t e
Actinides^[1] by decay chain				Half-life range (a)	Fission products of ²³⁵U by yield^[2]
4n	4n + 1	4n + 2	4n + 3	Half-life range (a)	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^[3]	²⁴⁹Cf^ƒ	^242mAm^ƒ		141–351 a	No fission products have a half-life in the range of 100 a–210 ka ...
	²⁴¹Am^ƒ		²⁵¹Cf^ƒ^[4]	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^[5]
²³²Th^№		²³⁸U^№	²³⁵U^ƒ№	0.7–14.1 Ga	... nor beyond 15.7 Ma^[5]
₡, has thermal neutron capture cross section in the range of 8–50 barns ƒ, fissile №, primarily a naturally occurring radioactive material (NORM) þ, neutron poison (thermal neutron capture cross section greater than 3k barns)

Protactinium (Pa) has no stable isotopes. There are three naturally-occurring isotopes, allowing a standard mass to be given.

Standard atomic mass: 231.03588(2) u

29 radioisotopes of protactinium have been characterized, with the most stable being ²³¹Pa with a half life of 32760 years, ²³³Pa with a half-life of 26.967 days, and ²³⁰Pa with a half-life of 17.4 days. All of the remaining radioactive isotopes have half-lives that are less than 1.6 days, and the majority of these have half lifes that are less than 1.8 seconds. This element also has 3 meta states, ^217mPa (t_½ 1.15 milliseconds), ^229mPa (t_½ 420 nanoseconds), and ^234mPa (t_½ 1.17 minutes).

The only naturally-occurring isotopes are ²³¹Pa, which occurs as an intermediate decay product of ²³⁵U, ²³⁴Pa and ^234mPa, both of which occur as intermediate decay products of ²³⁸U. ²³¹Pa makes up nearly all natural protactinium.

The primary decay mode for isotopes of Pa lighter than (and including) the most stable isotope ²³¹Pa is alpha decay, except for ²²⁸Pa to ²³⁰Pa, which primarily decay by electron capture to isotopes of thorium. The primary mode for the heavier isotopes is beta minus (β⁻) decay. The primary decay products of ²³¹Pa and isotopes of Pa lighter than (and including ²²⁷Pa) are element Ac (actinium) isotopes and the primary decay products for the heavier isotopes of Pa are element U (uranium) isotopes.

Protactinium-230

Protactinium-230 is a radioactive isotope of protactinium. It has 139 neutrons. It has a half life of 17.4 days. After a beta minus decay it turns into uranium-230. It is not found in nature because it is highly unstable, with a half life of only 17.4 days, and is not found in the decay chains of ²³⁵U, ²³⁸U, or ²³²Th. It has a mass of 230.034541 grams/mole.

Protactinium-231


Transmutations in the thorium fuel cycle v t e
														²³⁷Np
														↑
		²³¹U	←	²³²U	↔	²³³U	↔	²³⁴U	↔	²³⁵U	↔	²³⁶U	→	²³⁷U
		↓		↑		↑		↑
		²³¹Pa	→	²³²Pa	←	²³³Pa	→	²³⁴Pa
		↑				↑
²³⁰Th	→	²³¹Th	←	²³²Th	→	²³³Th
Nuclides with a yellow background in italic have half-lives under 30 days Nuclides in bold have half-lives over 1,000,000 years Nuclides in red frames are fissile

Protactinium-231 is the longest-lived isotope of protactinium, with a half life of 32,760 years. In nature, it is found in trace amounts as part of the actinium series which starts with the primordial isotope uranium-235; the equilibrium concentration in uranium ore is 46.55 Pa-231 per million U-235.

In nuclear reactors, it is one of the few long-lived radioactive actinides produced as a byproduct of the projected thorium fuel cycle, as a result of (n,2n) reactions where a fast neutron removes a neutron from thorium-232 or uranium-232, and can also be destroyed by neutron capture though the cross section for this reaction is also low.

binding energy: 1759860 keV
beta decay energy: -382 keV

spin: 3/2-
mode of decay: alpha to Ac-227, also others

possible parent nuclides: beta from Th-231, EC from U-231, alpha from Np-235

Table

nuclide symbol	historic name	Z(p)	N(n)	isotopic mass (u)	half-life	decay mode(s)^[6]^{[n 1]}	daughter isotope(s)	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
nuclide symbol	historic name	excitation energy			half-life	decay mode(s)^[6]^{[n 1]}	daughter isotope(s)	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
²¹²Pa		91	121	212.02320(8)	8(5) ms [5.1(+61-19) ms]			7+#
²¹³Pa		91	122	213.02111(8)	7(3) ms [5.3(+40-16) ms]	α	²⁰⁹Ac	9/2-#
²¹⁴Pa		91	123	214.02092(8)	17(3) ms	α	²¹⁰Ac
²¹⁵Pa		91	124	215.01919(9)	14(2) ms	α	²¹¹Ac	9/2-#
²¹⁶Pa		91	125	216.01911(8)	105(12) ms	α (80%)	²¹²Ac
²¹⁶Pa		91	125	216.01911(8)	105(12) ms	β⁺ (20%)	²¹⁶Th
²¹⁷Pa		91	126	217.01832(6)	3.48(9) ms	α	²¹³Ac	9/2-#
^217mPa		1860(7) keV			1.08(3) ms	α	²¹³Ac	29/2+#
^217mPa		1860(7) keV			1.08(3) ms	IT (rare)	²¹⁷Pa	29/2+#
²¹⁸Pa		91	127	218.020042(26)	0.113(1) ms	α	²¹⁴Ac
²¹⁹Pa		91	128	219.01988(6)	53(10) ns	α	²¹⁵Ac	9/2-
²¹⁹Pa		91	128	219.01988(6)	53(10) ns	β⁺ (5E-9%)	²¹⁹Th	9/2-
²²⁰Pa		91	129	220.02188(6)	780(160) ns	α	²¹⁶Ac	1-#
²²¹Pa		91	130	221.02188(6)	4.9(8) µs	α	²¹⁷Ac	9/2-
²²²Pa		91	131	222.02374(8)#	3.2(3) ms	α	²¹⁸Ac
²²³Pa		91	132	223.02396(8)	5.1(6) ms	α	²¹⁹Ac
²²³Pa		91	132	223.02396(8)	5.1(6) ms	β⁺ (.001%)	²²³Th
²²⁴Pa		91	133	224.025626(17)	844(19) ms	α (99.9%)	²²⁰Ac	5-#
²²⁴Pa		91	133	224.025626(17)	844(19) ms	β⁺ (.1%)	²²⁴Th	5-#
²²⁵Pa		91	134	225.02613(8)	1.7(2) s	α	²²¹Ac	5/2-#
²²⁶Pa		91	135	226.027948(12)	1.8(2) min	α (74%)	²²²Ac
²²⁶Pa		91	135	226.027948(12)	1.8(2) min	β⁺ (26%)	²²⁶Th
²²⁷Pa		91	136	227.028805(8)	38.3(3) min	α (85%)	²²³Ac	(5/2-)
²²⁷Pa		91	136	227.028805(8)	38.3(3) min	EC (15%)	²²⁷Th	(5/2-)
²²⁸Pa		91	137	228.031051(5)	22(1) h	β⁺ (98.15%)	²²⁸Th	3+
²²⁸Pa		91	137	228.031051(5)	22(1) h	α (1.85%)	²²⁴Ac	3+
²²⁹Pa		91	138	229.0320968(30)	1.50(5) d	EC (99.52%)	²²⁹Th	(5/2+)
²²⁹Pa		91	138	229.0320968(30)	1.50(5) d	α (.48%)	²²⁵Ac	(5/2+)
^229mPa		11.6(3) keV			420(30) ns			3/2-
²³⁰Pa		91	139	230.034541(4)	17.4(5) d	β⁺ (91.6%)	²³⁰Th	(2-)
						β^- (8.4%)	²³⁰U
						α (.00319%)	²²⁶Ac
²³¹Pa	Protoactinium	91	140	231.0358840(24)	3.276(11)E+4 a	α	²²⁷Ac	3/2-	1.0000^{[n 2]}
						CD (1.34E-9%)	²⁰⁷Tl, ²⁴Ne
						SF (3E-10%)	(various)
						CD (1E-12%)	²⁰⁸Pb, ²³F
²³²Pa		91	141	232.038592(8)	1.31(2) d	β^-	²³²U	(2-)
²³²Pa		91	141	232.038592(8)	1.31(2) d	EC (.003%)	²³²Th	(2-)
²³³Pa		91	142	233.0402473(23)	26.975(13) d	β^-	²³³U	3/2-
²³⁴Pa	Uranium Z	91	143	234.043308(5)	6.70(5) h	β^-	²³⁴U	4+	^{[n 3]}
²³⁴Pa	Uranium Z	91	143	234.043308(5)	6.70(5) h	SF (3E-10%)	(various)	4+	^{[n 3]}
^234mPa	Uranium X₂ Brevium	78(3) keV			1.17(3) min	β^- (99.83%)	²³⁴U	(0-)	^{[n 3]}
						IT (.16%)	²³⁴Pa
						SF (1E-10%)	(various)
²³⁵Pa		91	144	235.04544(5)	24.44(11) min	β^-	^235mU	(3/2-)
²³⁶Pa		91	145	236.04868(21)	9.1(1) min	β^-	²³⁶U	1(-)
²³⁶Pa		91	145	236.04868(21)	9.1(1) min	β^-, SF	(various)	1(-)
²³⁷Pa		91	146	237.05115(11)	8.7(2) min	β^-	²³⁷U	(1/2+)
²³⁸Pa		91	147	238.05450(6)	2.27(9) min	β^-	²³⁸U	(3-)#
²³⁸Pa		91	147	238.05450(6)	2.27(9) min	β^-, SF (6E-8%)	(various)	(3-)#
²³⁹Pa		91	148	239.05726(21)#	1.8(5) h	β^-	²³⁹U	(3/2)(-#)
²⁴⁰Pa		91	149	240.06098(32)#	2# min	β^-	²⁴⁰U

^ Abbreviations:
CD: Cluster decay
EC: Electron capture
IT: Isomeric transition
SF: Spontaneous fission
^ Occurs as an intermediate decay product of ²³⁵U
^ ^a ^b Occurs in trace quantities in nature as an intermediate decay product of ²³⁸U

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

^ 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 uranium-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 eight quadrillion years.
^ http://www.nucleonica.net/unc.aspx

Isotope masses from:
- G. Audi, A. H. Wapstra, C. Thibault, J. Blachot and O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A. 729: 3–128. doi:10.1016/j.nuclphysa.2003.11.001.{{cite journal}}: CS1 maint: multiple names: authors list (link)
Isotopic compositions and standard atomic masses from:
- J. R. de Laeter, J. K. Böhlke, P. De Bièvre, H. Hidaka, H. S. Peiser, K. J. R. Rosman and P. D. P. Taylor (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683.{{cite journal}}: CS1 maint: multiple names: authors list (link)
- M. E. Wieser (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry. 78 (11): 2051–2066. doi:10.1351/pac200678112051. {{cite journal}}: Unknown parameter |laysummary= ignored (help)
Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.
- G. Audi, A. H. Wapstra, C. Thibault, J. Blachot and O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A. 729: 3–128. doi:10.1016/j.nuclphysa.2003.11.001.{{cite journal}}: CS1 maint: multiple names: authors list (link)
- National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. Retrieved September 2005. {{cite web}}: Check date values in: |accessdate= (help)
- N. E. Holden (2004). "Table of the Isotopes". In D. R. Lide (ed.). CRC Handbook of Chemistry and Physics (85th ed.). CRC Press. Section 11. ISBN 978-0849304859. {{cite book}}: Unknown parameter |nopp= ignored (|no-pp= suggested) (help)

[7] Abbreviations:
CD: Cluster decay
EC: Electron capture
IT: Isomeric transition
SF: Spontaneous fission

[8] Occurs as an intermediate decay product of ²³⁵U

[us-9] Occurs in trace quantities in nature as an intermediate decay product of ²³⁸U

[1] 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.

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

[3] 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]."

[4] This is the heaviest nuclide with a half-life of at least four years before the "sea of instability".

[5] 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.

[6] ttp://www.nucleonica.net/unc.aspx

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