Isotopes of gadolinium
List of isotopes
Bold for isotopes with half-lives longer than the age of the universe (nearly stable) Abbreviations: EC: Electron capture IT: Isomeric transition Bold for stable isotopes, bold italics for nearly-stable isotopes (half-life longer than the age of the universe) primordial radionuclide Believed to undergo α decay to ¹⁵⁰Sm Fission product Believed to undergo α decay to ¹⁵¹Sm Believed to undergo β−β− decay to ¹⁶⁰Dy with a half-life over 1.3×10²¹ years

Isotopes of gadolinium

Section Title: List of isotopes
Table Section Text: Bold for isotopes with half-lives longer than the age of the universe (nearly stable) Abbreviations: EC: Electron capture IT: Isomeric transition Bold for stable isotopes, bold italics for nearly-stable isotopes (half-life longer than the age of the universe) primordial radionuclide Believed to undergo α decay to ¹⁵⁰Sm Fission product Believed to undergo α decay to ¹⁵¹Sm Believed to undergo β−β− decay to ¹⁶⁰Dy with a half-life over 1.3×10²¹ years

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life	decay mode(s)	daughter isotope(s)	nuclear spin and parity	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)

excitation energy

134Gd	64	70	133.95537(43)#	0.4# s	0+

135Gd	64	71	134.95257(54)#	1.1(2) s	3/2−

136Gd	64	72	135.94734(43)#	1# s [>200 ns]	β+	136Eu

137Gd	64	73	136.94502(43)#	2.2(2) s	β+	137Eu	7/2+#

β+, p (rare)	136Sm

138Gd	64	74	137.94012(21)#	4.7(9) s	β+	138Eu	0+

138mGd	2232.7(11) keV	6(1) µs	(8−)

139Gd	64	75	138.93824(21)#	5.7(3) s	β+	139Eu	9/2−#

β+, p (rare)	138Sm

139mGd	250(150)# keV	4.8(9) s	1/2+#

140Gd	64	76	139.93367(3)	15.8(4) s	β+	140Eu	0+

141Gd	64	77	140.932126(21)	14(4) s	β+ (99.97%)	141Eu	(1/2+)

β+, p (.03%)	140Sm

141mGd	377.8(2) keV	24.5(5) s	β+ (89%)	141Eu	(11/2−)

IT (11%)	141Gd

142Gd	64	78	141.92812(3)	70.2(6) s	β+	142Eu	0+

143Gd	64	79	142.92675(22)	39(2) s	β+	143Eu	(1/2)+

β+, α (rare)	139Pm

β+, p (rare)	142Sm

143mGd	152.6(5) keV	110.0(14) s	β+	143Eu	(11/2−)

β+, α (rare)	139Pm

β+, p (rare)	142Sm

144Gd	64	80	143.92296(3)	4.47(6) min	β+	144Eu	0+

145Gd	64	81	144.921709(20)	23.0(4) min	β+	145Eu	1/2+

145mGd	749.1(2) keV	85(3) s	IT (94.3%)	145Gd	11/2−

β+ (5.7%)	145Eu

146Gd	64	82	145.918311(5)	48.27(10) d	EC	146Eu	0+

147Gd	64	83	146.919094(3)	38.06(12) h	β+	147Eu	7/2−

147mGd	8587.8(4) keV	510(20) ns	(49/2+)

148Gd	64	84	147.918115(3)	74.6(30) y	α	144Sm	0+

β+β+ (rare)	148Sm

149Gd	64	85	148.919341(4)	9.28(10) d	β+	149Eu	7/2−

α (4.34×10−4%)	145Sm

150Gd	64	86	149.918659(7)	1.79(8)×106 y	α	146Sm	0+

β+β+ (rare)	150Sm

151Gd	64	87	150.920348(4)	124(1) d	EC	151Eu	7/2−

α (10−6%)	147Sm

152Gd	64	88	151.9197910(27)	1.08(8)×1014 y	α	148Sm	0+	0.0020(1)

153Gd	64	89	152.9217495(27)	240.4(10) d	EC	153Eu	3/2−

153m1Gd	95.1737(12) keV	3.5(4) µs	(9/2+)

153m2Gd	171.189(5) keV	76.0(14) µs	(11/2−)

154Gd	64	90	153.9208656(27)	Observationally Stable	0+	0.0218(3)

155Gd	64	91	154.9226220(27)	Observationally Stable	3/2−	0.1480(12)

155mGd	121.05(19) keV	31.97(27) ms	IT	155Gd	11/2−

156Gd	64	92	155.9221227(27)	Stable	0+	0.2047(9)

156mGd	2137.60(5) keV	1.3(1) µs	7-

157Gd	64	93	156.9239601(27)	Stable	3/2−	0.1565(2)

158Gd	64	94	157.9241039(27)	Stable	0+	0.2484(7)

159Gd	64	95	158.9263887(27)	18.479(4) h	β−	159Tb	3/2−

160Gd	64	96	159.9270541(27)	Observationally Stable	0+	0.2186(19)

161Gd	64	97	160.9296692(29)	3.646(3) min	β−	161Tb	5/2−

162Gd	64	98	161.930985(5)	8.4(2) min	β−	162Tb	0+

163Gd	64	99	162.93399(32)#	68(3) s	β−	163Tb	7/2+#

164Gd	64	100	163.93586(43)#	45(3) s	β−	164Tb	0+

165Gd	64	101	164.93938(54)#	10.3(16) s	β−	165Tb	1/2−#

166Gd	64	102	165.94160(64)#	4.8(10) s	β−	166Tb	0+

167Gd	64	103	166.94557(64)#	3# s	β−	167Tb	5/2−#

168Gd	64	104	167.94836(75)#	300# ms	β−	168Tb	0+

169Gd	64	105	168.95287(86)#	1# s	β−	169Tb	7/2−#

Sentence(s)

The alpha-decaying isotopes are ¹⁵²Gd with a half-life of 1.08×10¹⁴ years and ¹⁵⁰Gd with a half-life of 1.79×10⁶ years.

final_sentence: The alpha-decaying isotopes are ¹⁵²Gd with a half-life of 1.08×10¹⁴ years and ¹⁵⁰Gd with a half-life of 1.79×10⁶ years.