Naturally occurring

europium Europium is a chemical element with the symbol Eu and atomic number 63. Europium is the most reactive lanthanide by far, having to be stored under an inert fluid to protect it from atmospheric oxygen or moisture. Europium is also the softest lanth ...

(₆₃Eu) is composed of two

isotope Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numbers) ...

s, ¹⁵¹Eu and ¹⁵³Eu, with ¹⁵³Eu being the most abundant (52.2%

natural abundance In physics, natural abundance (NA) refers to the abundance of isotopes of a chemical element as naturally found on a planet. The relative atomic mass (a weighted average, weighted by mole-fraction abundance figures) of these isotopes is the atomic ...

). While ¹⁵³Eu is observationally stable, ¹⁵¹Eu was found in 2007 to be unstable and undergo

alpha decay Alpha decay or α-decay is a type of radioactive decay in which an atomic nucleus emits an alpha particle (helium nucleus) and thereby transforms or 'decays' into a different atomic nucleus, with a mass number that is reduced by four and an atom ...

. The

half-life Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable ato ...

is measured to be (4.62 ± 0.95(stat.) ± 0.68(syst.)) × 10¹⁸ years which corresponds to 1 alpha decay per two minutes in every kilogram of natural europium. Besides the natural radioisotope ¹⁵¹Eu, 36 artificial radioisotopes have been characterized, with the most stable being ¹⁵⁰Eu with a

of 36.9 years, ¹⁵²Eu with a half-life of 13.516 years, ¹⁵⁴Eu with a half-life of 8.593 years, and ¹⁵⁵Eu with a half-life of 4.7612 years. The majority of the remaining

radioactive Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is consid ...

isotopes, which range from ¹³⁰Eu to ¹⁷⁰Eu, have half-lives that are less than 12.2 seconds. This element also has 18 meta states, with the most stable being ^150mEu (t_1/2 12.8 hours), ^152m1Eu (t_1/2 9.3116 hours) and ^152m2Eu (t_1/2 96 minutes). The primary

decay mode Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is consid ...

before the most abundant stable isotope, ¹⁵³Eu, is

electron capture Electron capture (K-electron capture, also K-capture, or L-electron capture, L-capture) is a process in which the proton-rich nucleus of an electrically neutral atom absorbs an inner atomic electron, usually from the K or L electron shells. Thi ...

, and the primary mode after is

beta decay In nuclear physics, beta decay (β-decay) is a type of radioactive decay in which a beta particle (fast energetic electron or positron) is emitted from an atomic nucleus, transforming the original nuclide to an isobar of that nuclide. For ...

. The primary

decay product In nuclear physics, a decay product (also known as a daughter product, daughter isotope, radio-daughter, or daughter nuclide) is the remaining nuclide left over from radioactive decay. Radioactive decay often proceeds via a sequence of steps ( ...

s before ¹⁵³Eu are isotopes of samarium and the primary products after are isotopes of gadolinium.

List of isotopes

, - , ¹³⁰Eu , style="text-align:right" , 63 , style="text-align:right" , 67 , 129.96357(54)# , 1.1(5) ms
.9(+5−3) ms, , , 2+# , , , - , ¹³¹Eu , style="text-align:right" , 63 , style="text-align:right" , 68 , 130.95775(43)# , 17.8(19) ms , , , 3/2+ , , , - , rowspan=2, ¹³²Eu , rowspan=2 style="text-align:right" , 63 , rowspan=2 style="text-align:right" , 69 , rowspan=2, 131.95437(43)# , rowspan=2, 100# ms , β⁺ , ¹³²Sm , rowspan=2, , rowspan=2, , rowspan=2, , - , p , ¹³¹Sm , - , ¹³³Eu , style="text-align:right" , 63 , style="text-align:right" , 70 , 132.94924(32)# , 200# ms , β⁺ , ¹³³Sm , 11/2−# , , , - , rowspan=2, ¹³⁴Eu , rowspan=2 style="text-align:right" , 63 , rowspan=2 style="text-align:right" , 71 , rowspan=2, 133.94651(21)# , rowspan=2, 0.5(2) s , β⁺ , ¹³⁴Sm , rowspan=2, , rowspan=2, , rowspan=2, , - , β⁺, p (rare) , ¹³³Pm , - , rowspan=2, ¹³⁵Eu , rowspan=2 style="text-align:right" , 63 , rowspan=2 style="text-align:right" , 72 , rowspan=2, 134.94182(32)# , rowspan=2, 1.5(2) s , β⁺ , ¹³⁵Sm , rowspan=2, 11/2−# , rowspan=2, , rowspan=2, , - , β⁺, p , ¹³⁴Pm , - , rowspan=2, ¹³⁶Eu , rowspan=2 style="text-align:right" , 63 , rowspan=2 style="text-align:right" , 73 , rowspan=2, 135.93960(21)# , rowspan=2, 3.3(3) s , β⁺ (99.91%) , ¹³⁶Sm , rowspan=2, (7+) , rowspan=2, , rowspan=2, , - , β⁺, p (.09%) , ¹³⁵Pm , - , rowspan=2 style="text-indent:1em" , ^136mEu , rowspan=2 colspan="3" style="text-indent:2em" , 0(500)# keV , rowspan=2, 3.8(3) s , β⁺ (99.91%) , ¹³⁶Sm , rowspan=2, (3+) , rowspan=2, , rowspan=2, , - , β⁺, p (.09%) , ¹³⁵Pm , - , ¹³⁷Eu , style="text-align:right" , 63 , style="text-align:right" , 74 , 136.93557(21)# , 8.4(5) s , β⁺ , ¹³⁷Sm , 11/2−# , , , - , ¹³⁸Eu , style="text-align:right" , 63 , style="text-align:right" , 75 , 137.93371(3) , 12.1(6) s , β⁺ , ¹³⁸Sm , (6−) , , , - , ¹³⁹Eu , style="text-align:right" , 63 , style="text-align:right" , 76 , 138.929792(14) , 17.9(6) s , β⁺ , ¹³⁹Sm , (11/2)− , , , - , ¹⁴⁰Eu , style="text-align:right" , 63 , style="text-align:right" , 77 , 139.92809(6) , 1.51(2) s , β⁺ , ¹⁴⁰Sm , 1+ , , , - , rowspan=2 style="text-indent:1em" , ^140mEu , rowspan=2 colspan="3" style="text-indent:2em" , 210(15) keV , rowspan=2, 125(2) ms , IT (99%) , ¹⁴⁰Eu , rowspan=2, 5−# , rowspan=2, , rowspan=2, , - , β⁺(1%) , ¹⁴⁰Sm , - , ¹⁴¹Eu , style="text-align:right" , 63 , style="text-align:right" , 78 , 140.924931(14) , 40.7(7) s , β⁺ , ¹⁴¹Sm , 5/2+ , , , - , rowspan=2 style="text-indent:1em" , ^141mEu , rowspan=2 colspan="3" style="text-indent:2em" , 96.45(7) keV , rowspan=2, 2.7(3) s , IT (86%) , ¹⁴¹Eu , rowspan=2, 11/2− , rowspan=2, , rowspan=2, , - , β⁺ (14%) , ¹⁴¹Sm , - , ¹⁴²Eu , style="text-align:right" , 63 , style="text-align:right" , 79 , 141.92343(3) , 2.36(10) s , β⁺ , ¹⁴²Sm , 1+ , , , - , style="text-indent:1em" , ^142mEu , colspan="3" style="text-indent:2em" , 460(30) keV , 1.223(8) min , β⁺ , ¹⁴²Sm , 8− , , , - , ¹⁴³Eu , style="text-align:right" , 63 , style="text-align:right" , 80 , 142.920298(12) , 2.59(2) min , β⁺ , ¹⁴³Sm , 5/2+ , , , - , style="text-indent:1em" , ^143mEu , colspan="3" style="text-indent:2em" , 389.51(4) keV , 50.0(5) µs , , , 11/2− , , , - , ¹⁴⁴Eu , style="text-align:right" , 63 , style="text-align:right" , 81 , 143.918817(12) , 10.2(1) s , β⁺ , ¹⁴⁴Sm , 1+ , , , - , style="text-indent:1em" , ^144mEu , colspan="3" style="text-indent:2em" , 1127.6(6) keV , 1.0(1) µs , , , (8−) , , , - , ¹⁴⁵Eu , style="text-align:right" , 63 , style="text-align:right" , 82 , 144.916265(4) , 5.93(4) d , β⁺ , ¹⁴⁵Sm , 5/2+ , , , - , style="text-indent:1em" , ^145mEu , colspan="3" style="text-indent:2em" , 716.0(3) keV , 490 ns , , , 11/2− , , , - , ¹⁴⁶Eu , style="text-align:right" , 63 , style="text-align:right" , 83 , 145.917206(7) , 4.61(3) d , β⁺ , ¹⁴⁶Sm , 4− , , , - , style="text-indent:1em" , ^146mEu , colspan="3" style="text-indent:2em" , 666.37(16) keV , 235(3) µs , , , 9+ , , , - , rowspan=2, ¹⁴⁷Eu , rowspan=2 style="text-align:right" , 63 , rowspan=2 style="text-align:right" , 84 , rowspan=2, 146.916746(3) , rowspan=2, 24.1(6) d , β⁺ (99.99%) , ''¹⁴⁷Sm'' , rowspan=2, 5/2+ , rowspan=2, , rowspan=2, , - , α (.0022%) , ¹⁴³Pm , - , rowspan=2, ¹⁴⁸Eu , rowspan=2 style="text-align:right" , 63 , rowspan=2 style="text-align:right" , 85 , rowspan=2, 147.918086(11) , rowspan=2, 54.5(5) d , β⁺ (100%) , ''¹⁴⁸Sm'' , rowspan=2, 5− , rowspan=2, , rowspan=2, , - , α (9.39×10⁻⁷%) , ¹⁴⁴Pm , - , ¹⁴⁹Eu , style="text-align:right" , 63 , style="text-align:right" , 86 , 148.917931(5) , 93.1(4) d , EC , ¹⁴⁹Sm , 5/2+ , , , - , ¹⁵⁰Eu , style="text-align:right" , 63 , style="text-align:right" , 87 , 149.919702(7) , 36.9(9) y , β⁺ , ¹⁵⁰Sm , 5(−) , , , - , rowspan=3 style="text-indent:1em" , ^150mEu , rowspan=3 colspan="3" style="text-indent:2em" , 42.1(5) keV , rowspan=3, 12.8(1) h , β⁻ (89%) , ¹⁵⁰Gd , rowspan=3, 0− , rowspan=3, , rowspan=3, , - , β⁺ (11%) , ¹⁵⁰Sm , - , IT (5×10⁻⁸%) , ¹⁵⁰Eu , - , ¹⁵¹Eu

primordial Primordial may refer to: * Primordial era, an era after the Big Bang. See Chronology of the universe * Primordial sea (a.k.a. primordial ocean, ooze or soup). See Abiogenesis * Primordial nuclide, nuclides, a few radioactive, that formed before ...

radionuclide A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transfer ...

, style="text-align:right" , 63 , style="text-align:right" , 88 , 150.9198502(26) , 4.62×10¹⁸ y , α , ¹⁴⁷Pm , 5/2+ , 0.4781(6) , , - , style="text-indent:1em" , ^151mEu , colspan="3" style="text-indent:2em" , 196.245(10) keV , 58.9(5) µs , , , 11/2− , , , - , rowspan=2, ¹⁵²Eu , rowspan=2 style="text-align:right" , 63 , rowspan=2 style="text-align:right" , 89 , rowspan=2, 151.9217445(26) , rowspan=2, 13.537(6) y , EC (72.09%), β⁺ (0.027%) , ¹⁵²Sm , rowspan=2, 3− , rowspan=2, , rowspan=2, , - , β⁻ (27.9%) , ''¹⁵²Gd'' , - , rowspan=2 style="text-indent:1em" , ^152m1Eu , rowspan=2 colspan="3" style="text-indent:2em" , 45.5998(4) keV , rowspan=2, 9.3116(13) h , β⁻ (72%) , ''¹⁵²Gd'' , rowspan=2, 0− , rowspan=2, , rowspan=2, , - , β⁺ (28%) , ¹⁵²Sm , - , style="text-indent:1em" , ^152m2Eu , colspan="3" style="text-indent:2em" , 65.2969(4) keV , 0.94(8) µs , , , 1− , , , - , style="text-indent:1em" , ^152m3Eu , colspan="3" style="text-indent:2em" , 78.2331(4) keV , 165(10) ns , , , 1+ , , , - , style="text-indent:1em" , ^152m4Eu , colspan="3" style="text-indent:2em" , 89.8496(4) keV , 384(10) ns , , , 4+ , , , - , style="text-indent:1em" , ^152m5Eu , colspan="3" style="text-indent:2em" , 147.86(10) keV , 96(1) min , , , 8− , , , - , ¹⁵³Eu

Fission product Nuclear fission products are the atomic fragments left after a large atomic nucleus undergoes nuclear fission. Typically, a large nucleus like that of uranium fissions by splitting into two smaller nuclei, along with a few neutrons, the release ...

, style="text-align:right" , 63 , style="text-align:right" , 90 , 152.9212303(26) , colspan=3 align=center, Observationally StableBelieved to undergo α decay to ¹⁴⁹Pm with a half-life over , 5/2+ , 0.5219(6) , , - , rowspan=2, ¹⁵⁴Eu , rowspan=2 style="text-align:right" , 63 , rowspan=2 style="text-align:right" , 91 , rowspan=2, 153.9229792(26) , rowspan=2, 8.593(4) y , β⁻ (99.98%) , ¹⁵⁴Gd , rowspan=2, 3− , rowspan=2, , rowspan=2, , - , EC (.02%) , ¹⁵⁴Sm , - , style="text-indent:1em" , ^154m1Eu , colspan="3" style="text-indent:2em" , 145.3(3) keV , 46.3(4) min , IT , ¹⁵⁴Eu , (8−) , , , - , style="text-indent:1em" , ^154m2Eu , colspan="3" style="text-indent:2em" , 68.1702(4) keV , 2.2(1) µs , , , 2+ , , , - , ¹⁵⁵Eu , style="text-align:right" , 63 , style="text-align:right" , 92 , 154.9228933(27) , 4.7611(13) y , β⁻ , ¹⁵⁵Gd , 5/2+ , , , - , ¹⁵⁶Eu , style="text-align:right" , 63 , style="text-align:right" , 93 , 155.924752(6) , 15.19(8) d , β⁻ , ¹⁵⁶Gd , 0+ , , , - , ¹⁵⁷Eu , style="text-align:right" , 63 , style="text-align:right" , 94 , 156.925424(6) , 15.18(3) h , β⁻ , ¹⁵⁷Gd , 5/2+ , , , - , ¹⁵⁸Eu , style="text-align:right" , 63 , style="text-align:right" , 95 , 157.92785(8) , 45.9(2) min , β⁻ , ¹⁵⁸Gd , (1−) , , , - , ¹⁵⁹Eu , style="text-align:right" , 63 , style="text-align:right" , 96 , 158.929089(8) , 18.1(1) min , β⁻ , ¹⁵⁹Gd , 5/2+ , , , - , ¹⁶⁰Eu , style="text-align:right" , 63 , style="text-align:right" , 97 , 159.93197(22)# , 38(4) s , β⁻ , ¹⁶⁰Gd , 1(−) , , , - , ¹⁶¹Eu , style="text-align:right" , 63 , style="text-align:right" , 98 , 160.93368(32)# , 26(3) s , β⁻ , ¹⁶¹Gd , 5/2+# , , , - , ¹⁶²Eu , style="text-align:right" , 63 , style="text-align:right" , 99 , 161.93704(32)# , 10.6(10) s , β⁻ , ¹⁶²Gd , , , , - , ¹⁶³Eu , style="text-align:right" , 63 , style="text-align:right" , 100 , 162.93921(54)# , 7.7(4) s , β⁻ , ¹⁶³Gd , 5/2+# , , , - , style="text-indent:1em" , ^163mEu , colspan="3" style="text-indent:2em" , 964.5(10) keV , 911(24) ns , , , (13/2−) , , , - , ¹⁶⁴Eu , style="text-align:right" , 63 , style="text-align:right" , 101 , 163.94299(64)# , 4.16(19) s , β⁻ , ¹⁶⁴Gd , , , , - , ¹⁶⁵Eu , style="text-align:right" , 63 , style="text-align:right" , 102 , 164.94572(75)# , , β⁻ , ¹⁶⁵Gd , 5/2+# , , , - , rowspan=2, ¹⁶⁶Eu , rowspan=2 style="text-align:right" , 63 , rowspan=2 style="text-align:right" , 103 , rowspan=2, 165.94997(86)# , rowspan=2, , β⁻ (99.37%) , ¹⁶⁶Gd , rowspan=2, , rowspan=2, , rowspan=2, , - , β⁻, n (0.63%) , ¹⁶⁵Gd , - , rowspan=2, ¹⁶⁷Eu , rowspan=2 style="text-align:right" , 63 , rowspan=2 style="text-align:right" , 104 , rowspan=2, 166.95321(86)# , rowspan=2, , β⁻ (98.05%) , ¹⁶⁷Gd , rowspan=2, 5/2+# , rowspan=2, , rowspan=2, , - , β⁻, n (1.95%) , ¹⁶⁶Gd , - , rowspan=2, ¹⁶⁸Eu , rowspan=2 style="text-align:right" , 63 , rowspan=2 style="text-align:right" , 105 , rowspan=2, , rowspan=2, , β⁻ (96.05%) , ¹⁶⁸Gd , rowspan=2, , rowspan=2, , rowspan=2, , - , β⁻, n (3.95%) , ¹⁶⁷Gd , - , rowspan=2, ¹⁶⁹Eu , rowspan=2 style="text-align:right" , 63 , rowspan=2 style="text-align:right" , 106 , rowspan=2, , rowspan=2, , β⁻ (85.38%) , ¹⁶⁹Gd , rowspan=2, , rowspan=2, , rowspan=2, , - , β⁻, n (14.62%) , ¹⁶⁸Gd , - , rowspan=2, ¹⁷⁰Eu , rowspan=2 style="text-align:right" , 63 , rowspan=2 style="text-align:right" , 107 , rowspan=2, , rowspan=2, , β⁻ , ¹⁷⁰Gd , rowspan=2, , rowspan=2, , rowspan=2, , - , β⁻, n , ¹⁶⁹Gd

Europium-155

Europium-155 is a

fission product Nuclear fission products are the atomic fragments left after a large atomic nucleus undergoes nuclear fission. Typically, a large nucleus like that of uranium fissions by splitting into two smaller nuclei, along with a few neutrons, the release ...

with a

of 4.76 years. It has a maximum decay energy of 252 keV. In a

thermal reactor A thermal-neutron reactor is a nuclear reactor that uses slow or thermal neutrons. ("Thermal" does not mean hot in an absolute sense, but means in thermal equilibrium with the medium it is interacting with, the reactor's fuel, moderator and struct ...

(almost all current

nuclear power plant A nuclear power plant (NPP) is a thermal power station in which the heat source is a nuclear reactor. As is typical of thermal power stations, heat is used to generate steam that drives a steam turbine connected to a electric generator, generato ...

s), it has a low

fission product yield Nuclear fission splits a heavy nucleus such as uranium or plutonium into two lighter nuclei, which are called fission products. Yield refers to the fraction of a fission product produced per fission. Yield can be broken down by: # Individual i ...

, about half of one percent as much as the most abundant fission products. ¹⁵⁵Eu's large

neutron capture Neutron capture is a nuclear reaction in which an atomic nucleus and one or more neutrons collide and merge to form a heavier nucleus. Since neutrons have no electric charge, they can enter a nucleus more easily than positively charged protons, ...

cross section Cross section may refer to: * Cross section (geometry) ** Cross-sectional views in architecture & engineering 3D *Cross section (geology) * Cross section (electronics) * Radar cross section, measure of detectability * Cross section (physics) **Abs ...

(about 3900 barns for

thermal neutrons The neutron detection temperature, also called the neutron energy, indicates a free neutron's kinetic energy, usually given in electron volts. The term ''temperature'' is used, since hot, thermal and cold neutrons are moderated in a medium with ...

, 16000

resonance integral Neutron capture is a nuclear reaction in which an atomic nucleus and one or more neutrons collide and merge to form a heavier nucleus. Since neutrons have no electric charge, they can enter a nucleus more easily than positively charged protons, ...

) means that most of even the small amount produced is destroyed in the course of the

nuclear fuel Nuclear fuel is material used in nuclear power stations to produce heat to power turbines. Heat is created when nuclear fuel undergoes nuclear fission. Most nuclear fuels contain heavy fissile actinide elements that are capable of undergoing ...

's burnup. Yield, decay energy, and half-life are all far less than that of ¹³⁷Cs and ⁹⁰Sr, so ¹⁵⁵Eu is not a significant contributor to nuclear waste. Some ¹⁵⁵Eu is also produced by successive neutron capture on ¹⁵³Eu (nonradioactive, 350 barns thermal, 1500 resonance integral, yield is about 5 times as great as ¹⁵⁵Eu) and ¹⁵⁴Eu (half-life 8.6 years, 1400 barns thermal, 1600 resonance integral, fission yield is extremely small because beta decay stops at ¹⁵⁴Sm). However, the differing cross sections mean that both ¹⁵⁵Eu and ¹⁵⁴Eu are destroyed faster than they are produced. ¹⁵⁴Eu is a prolific emitter of

gamma radiation A gamma ray, also known as gamma radiation (symbol γ or \gamma), is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nuclei. It consists of the shortest wavelength electromagnetic waves, typically s ...

References

* Isotope masses from: ** * Isotopic compositions and standard atomic masses from: ** ** * Half-life, spin, and isomer data selected from the following sources. ** ** ** {{Navbox element isotopes Europium

Europium Europium is a chemical element with the symbol Eu and atomic number 63. Europium is the most reactive lanthanide by far, having to be stored under an inert fluid to protect it from atmospheric oxygen or moisture. Europium is also the softest lanth ...