# Isotopes of tin

Tin ($_{50}$Sn) is the element with the greatest number of stable isotopes (ten; three of them are potentially radioactive but have not been observed to decay). This is probably related to the fact that 50 is a "magic number" of protons. In addition, twenty-nine unstable tin isotopes are known, including tin-100 ($^{100}$Sn) (discovered in 1994) and tin-132 ($^{132}$Sn), which are both "doubly magic". The longest-lived tin radioisotope is tin-126 ($^{126}$Sn), with a half-life of 230,000 years. The other 28 radioisotopes have half-lives of less than a year.

## List of isotopes

| Nuclide | Z | N | Isotopic mass (Da) | Half-life | Decay mode | Daughter isotope | Spin and parity | Natural abundance (mole fraction) | Natural abundance (mole fraction) |
| Nuclide | Excitation energy | Excitation energy | Excitation energy | Half-life | Decay mode | Daughter isotope | Spin and parity | Normal proportion | Range of variation |
| $^{99}$Sn | 50 | 49 | 98.94850(63)# | 24(4) ms | β$^+$ (95%) | $^{99}$In | 9/2+# | | |
| $^{99}$Sn | 50 | 49 | 98.94850(63)# | 24(4) ms | β$^+$p (5%) | $^{98}$Cd | 9/2+# | | |
| $^{100}$Sn | 50 | 50 | 99.93865(26) | 1.18(8) s | β$^+$ (>83%) | $^{100}$In | 0+ | | |
| $^{100}$Sn | 50 | 50 | 99.93865(26) | 1.18(8) s | β$^+$p (<17%) | $^{99}$Cd | 0+ | | |
| $^{101}$Sn | 50 | 51 | 100.93526(32) | 2.22(5) s | β$^+$ | $^{101}$In | (7/2+) | | |
| $^{101}$Sn | 50 | 51 | 100.93526(32) | 2.22(5) s | β$^+$p? | $^{100}$Cd | (7/2+) | | |
| $^{102}$Sn | 50 | 52 | 101.93029(11) | 3.8(2) s | β$^+$ | $^{102}$In | 0+ | | |
| $^{102m}$Sn | 2017(2) keV | 2017(2) keV | 2017(2) keV | 367(8) ns | IT | $^{102}$Sn | (6+) | | |
| $^{103}$Sn | 50 | 53 | 102.92797(11)# | 7.0(2) s | β$^+$ (98.8%) | $^{103}$In | 5/2+# | | |
| $^{103}$Sn | 50 | 53 | 102.92797(11)# | 7.0(2) s | β$^+$p (1.2%) | $^{102}$Cd | 5/2+# | | |
| $^{104}$Sn | 50 | 54 | 103.923105(6) | 20.8(5) s | β$^+$ | $^{104}$In | 0+ | | |
| $^{105}$Sn | 50 | 55 | 104.921268(4) | 32.7(5) s | β$^+$ | $^{105}$In | (5/2+) | | |
| $^{105}$Sn | 50 | 55 | 104.921268(4) | 32.7(5) s | β$^+$p (0.011%) | $^{104}$Cd | (5/2+) | | |
| $^{106}$Sn | 50 | 56 | 105.916957(5) | 1.92(8) min | β$^+$ | $^{106}$In | 0+ | | |
| $^{107}$Sn | 50 | 57 | 106.915714(6) | 2.90(5) min | β$^+$ | $^{107}$In | (5/2+) | | |
| $^{108}$Sn | 50 | 58 | 107.911894(6) | 10.30(8) min | β$^+$ | $^{108}$In | 0+ | | |
| $^{109}$Sn | 50 | 59 | 108.911293(9) | 18.1(2) min | β$^+$ | $^{109}$In | 5/2+ | | |
| $^{110}$Sn | 50 | 60 | 109.907845(15) | 4.154(4) h | EC | $^{110}$In | 0+ | | |
| $^{111}$Sn | 50 | 61 | 110.907741(6) | 35.3(6) min | β$^+$ | $^{111}$In | 7/2+ | | |
| $^{111m}$Sn | 254.71(4) keV | 254.71(4) keV | 254.71(4) keV | 12.5(10) μs | IT | $^{111}$Sn | 1/2+ | | |
| $^{112}$Sn | 50 | 62 | 111.9048249(3) | Observationally Stable | Observationally Stable | Observationally Stable | 0+ | 0.0097(1) | |
| $^{113}$Sn | 50 | 63 | 112.9051759(17) | 115.08(4) d | β$^+$ | $^{113}$In | 1/2+ | | |
| $^{113m}$Sn | 77.389(19) keV | 77.389(19) keV | 77.389(19) keV | 21.4(4) min | IT (91.1%) | $^{113}$Sn | 7/2+ | | |
| $^{113m}$Sn | 77.389(19) keV | 77.389(19) keV | 77.389(19) keV | 21.4(4) min | β$^+$ (8.9%) | $^{113}$In | 7/2+ | | |
| $^{114}$Sn | 50 | 64 | 113.90278013(3) | Stable | Stable | Stable | 0+ | 0.0066(1) | |
| $^{114m}$Sn | 3087.37(7) keV | 3087.37(7) keV | 3087.37(7) keV | 733(14) ns | IT | $^{114}$Sn | 7− | | |
| $^{115}$Sn | 50 | 65 | 114.903344695(16) | Stable | Stable | Stable | 1/2+ | 0.0034(1) | |
| $^{115m1}$Sn | 612.81(4) keV | 612.81(4) keV | 612.81(4) keV | 3.26(8) μs | IT | $^{115}$Sn | 7/2+ | | |
| $^{115m2}$Sn | 713.64(12) keV | 713.64(12) keV | 713.64(12) keV | 159(1) μs | IT | $^{115}$Sn | 11/2− | | |
| $^{116}$Sn | 50 | 66 | 115.90174283(10) | Stable | Stable | Stable | 0+ | 0.1454(9) | |
| $^{116m1}$Sn | 2365.975(21) keV | 2365.975(21) keV | 2365.975(21) keV | 348(19) ns | IT | $^{116}$Sn | 5− | | |
| $^{116m2}$Sn | 3547.16(17) keV | 3547.16(17) keV | 3547.16(17) keV | 833(30) ns | IT | $^{116}$Sn | 10+ | | |
| $^{117}$Sn | 50 | 67 | 116.90295404(52) | Stable | Stable | Stable | 1/2+ | 0.0768(7) | |
| $^{117m1}$Sn | 314.58(4) keV | 314.58(4) keV | 314.58(4) keV | 13.939(24) d | IT | $^{117}$Sn | 11/2− | | |
| $^{117m2}$Sn | 2406.4(4) keV | 2406.4(4) keV | 2406.4(4) keV | 1.75(7) μs | IT | $^{117}$Sn | (19/2+) | | |
| $^{118}$Sn | 50 | 68 | 117.90160663(54) | Stable | Stable | Stable | 0+ | 0.2422(9) | |
| $^{118m1}$Sn | 2574.91(4) keV | 2574.91(4) keV | 2574.91(4) keV | 230(10) ns | IT | $^{118}$Sn | 7− | | |
| $^{118m2}$Sn | 3108.06(22) keV | 3108.06(22) keV | 3108.06(22) keV | 2.52(6) μs | IT | $^{118}$Sn | (10+) | | |
| $^{119}$Sn | 50 | 69 | 118.90331127(78) | Stable | Stable | Stable | 1/2+ | 0.0859(4) | |
| $^{119m1}$Sn | 89.531(13) keV | 89.531(13) keV | 89.531(13) keV | 293.1(7) d | IT | $^{119}$Sn | 11/2− | | |
| $^{119m2}$Sn | 2127.0(10) keV | 2127.0(10) keV | 2127.0(10) keV | 9.6(12) μs | IT | $^{119}$Sn | (19/2+) | | |
| $^{119m3}$Sn | 2369.0(3) keV | 2369.0(3) keV | 2369.0(3) keV | 96(9) ns | IT | $^{119}$Sn | 23/2+ | | |
| $^{120}$Sn | 50 | 70 | 119.90220256(99) | Stable | Stable | Stable | 0+ | 0.3258(9) | |
| $^{120m1}$Sn | 2481.63(6) keV | 2481.63(6) keV | 2481.63(6) keV | 11.8(5) μs | IT | $^{120}$Sn | 7− | | |
| $^{120m2}$Sn | 2902.22(22) keV | 2902.22(22) keV | 2902.22(22) keV | 6.26(11) μs | IT | $^{120}$Sn | 10+ | | |
| $^{121}$Sn | 50 | 71 | 120.9042435(11) | 27.03(4) h | β$^−$ | $^{121}$Sb | 3/2+ | | |
| $^{121m1}$Sn | 6.31(6) keV | 6.31(6) keV | 6.31(6) keV | 43.9(5) y | IT (77.6%) | $^{121}$Sn | 11/2− | | |
| $^{121m1}$Sn | 6.31(6) keV | 6.31(6) keV | 6.31(6) keV | 43.9(5) y | β$^−$ (22.4%) | $^{121}$Sb | 11/2− | | |
| $^{121m2}$Sn | 1998.68(13) keV | 1998.68(13) keV | 1998.68(13) keV | 5.3(5) μs | IT | $^{121}$Sn | 19/2+ | | |
| $^{121m3}$Sn | 2222.0(2) keV | 2222.0(2) keV | 2222.0(2) keV | 520(50) ns | IT | $^{121}$Sn | 23/2+ | | |
| $^{121m4}$Sn | 2833.9(2) keV | 2833.9(2) keV | 2833.9(2) keV | 167(25) ns | IT | $^{121}$Sn | 27/2− | | |
| $^{122}$Sn | 50 | 72 | 121.9034455(26) | Observationally Stable | Observationally Stable | Observationally Stable | 0+ | 0.0463(3) | |
| $^{122m1}$Sn | 2409.03(4) keV | 2409.03(4) keV | 2409.03(4) keV | 7.5(9) μs | IT | $^{122}$Sn | 7− | | |
| $^{122m2}$Sn | 2765.5(3) keV | 2765.5(3) keV | 2765.5(3) keV | 62(3) μs | IT | $^{122}$Sn | 10+ | | |
| $^{122m3}$Sn | 4721.2(3) keV | 4721.2(3) keV | 4721.2(3) keV | 139(9) ns | IT | $^{122}$Sn | 15− | | |
| $^{123}$Sn | 50 | 73 | 122.9057271(27) | 129.2(4) d | β$^−$ | $^{123}$Sb | 11/2− | | |
| $^{123m1}$Sn | 24.6(4) keV | 24.6(4) keV | 24.6(4) keV | 40.06(1) min | β$^−$ | $^{123}$Sb | 3/2+ | | |
| $^{123m2}$Sn | 1944.90(12) keV | 1944.90(12) keV | 1944.90(12) keV | 7.4(26) μs | IT | $^{123}$Sn | 19/2+ | | |
| $^{123m3}$Sn | 2152.66(19) keV | 2152.66(19) keV | 2152.66(19) keV | 6 μs | IT | $^{123}$Sn | 23/2+ | | |
| $^{123m4}$Sn | 2712.47(21) keV | 2712.47(21) keV | 2712.47(21) keV | 34 μs | IT | $^{123}$Sn | 27/2− | | |
| $^{124}$Sn | 50 | 74 | 123.9052796(14) | Observationally Stable | Observationally Stable | Observationally Stable | 0+ | 0.0579(5) | |
| $^{124m1}$Sn | 2204.620(23) keV | 2204.620(23) keV | 2204.620(23) keV | 270(60) ns | IT | $^{124}$Sn | 5- | | |
| $^{124m2}$Sn | 2324.96(4) keV | 2324.96(4) keV | 2324.96(4) keV | 3.1(5) μs | IT | $^{124}$Sn | 7− | | |
| $^{124m3}$Sn | 2656.6(3) keV | 2656.6(3) keV | 2656.6(3) keV | 51(3) μs | IT | $^{124}$Sn | 10+ | | |
| $^{124m4}$Sn | 4552.4(3) keV | 4552.4(3) keV | 4552.4(3) keV | 260(25) ns | IT | $^{124}$Sn | 15− | | |
| $^{125}$Sn | 50 | 75 | 124.9077894(14) | 9.634(15) d | β$^−$ | $^{125}$Sb | 11/2− | | |
| $^{125m1}$Sn | 27.50(14) keV | 27.50(14) keV | 27.50(14) keV | 9.77(25) min | β$^−$ | $^{125}$Sb | 3/2+ | | |
| $^{125m2}$Sn | 1892.8(3) keV | 1892.8(3) keV | 1892.8(3) keV | 6.2(2) μs | IT | $^{125}$Sn | 19/2+ | | |
| $^{125m3}$Sn | 2059.5(4) keV | 2059.5(4) keV | 2059.5(4) keV | 650(60) ns | IT | $^{125}$Sn | 23/2+ | | |
| $^{125m4}$Sn | 2623.5(5) keV | 2623.5(5) keV | 2623.5(5) keV | 230(17) ns | IT | $^{125}$Sn | 27/2− | | |
| $^{126}$Sn | 50 | 76 | 125.907658(11) | 2.30(14)×10$^5$ y | β$^−$ | $^{126}$Sb | 0+ | < 10$^{−14}$ | |
| $^{126m1}$Sn | 2218.99(8) keV | 2218.99(8) keV | 2218.99(8) keV | 6.1(7) μs | IT | $^{126}$Sn | 7− | | |
| $^{126m2}$Sn | 2564.5(5) keV | 2564.5(5) keV | 2564.5(5) keV | 7.6(3) μs | IT | $^{126}$Sn | 10+ | | |
| $^{126m3}$Sn | 4347.4(4) keV | 4347.4(4) keV | 4347.4(4) keV | 114(2) ns | IT | $^{126}$Sn | 15− | | |
| $^{127}$Sn | 50 | 77 | 126.9103917(99) | 2.10(4) h | β$^−$ | $^{127}$Sb | 11/2− | | |
| $^{127m1}$Sn | 5.07(6) keV | 5.07(6) keV | 5.07(6) keV | 4.13(3) min | β$^−$ | $^{127}$Sb | 3/2+ | | |
| $^{127m2}$Sn | 1826.67(16) keV | 1826.67(16) keV | 1826.67(16) keV | 4.52(15) μs | IT | $^{127}$Sn | 19/2+ | | |
| $^{127m3}$Sn | 1930.97(17) keV | 1930.97(17) keV | 1930.97(17) keV | 1.26(15) μs | IT | $^{127}$Sn | (23/2+) | | |
| $^{127m4}$Sn | 2552.4(10) keV | 2552.4(10) keV | 2552.4(10) keV | 250 (30) ns | IT | $^{127}$Sn | (27/2−) | | |
| $^{128}$Sn | 50 | 78 | 127.910508(19) | 59.07(14) min | β$^−$ | $^{128}$Sb | 0+ | | |
| $^{128m1}$Sn | 2091.50(11) keV | 2091.50(11) keV | 2091.50(11) keV | 6.5(5) s | IT | $^{128}$Sn | 7− | | |
| $^{128m2}$Sn | 2491.91(17) keV | 2491.91(17) keV | 2491.91(17) keV | 2.91(14) μs | IT | $^{128}$Sn | 10+ | | |
| $^{128m3}$Sn | 4099.5(4) keV | 4099.5(4) keV | 4099.5(4) keV | 220(30) ns | IT | $^{128}$Sn | (15−) | | |
| $^{129}$Sn | 50 | 79 | 128.913482(19) | 2.23(4) min | β$^−$ | $^{129}$Sb | 3/2+ | | |
| $^{129m1}$Sn | 35.15(5) keV | 35.15(5) keV | 35.15(5) keV | 6.9(1) min | β$^−$ | $^{129}$Sb | 11/2− | | |
| $^{129m2}$Sn | 1761.6(10) keV | 1761.6(10) keV | 1761.6(10) keV | 3.49(11) μs | IT | $^{129}$Sn | (19/2+) | | |
| $^{129m3}$Sn | 1802.6(10) keV | 1802.6(10) keV | 1802.6(10) keV | 2.22(13) μs | IT | $^{129}$Sn | 23/2+ | | |
| $^{129m4}$Sn | 2552.9(11) keV | 2552.9(11) keV | 2552.9(11) keV | 221(18) ns | IT | $^{129}$Sn | (27/2−) | | |
| $^{130}$Sn | 50 | 80 | 129.9139745(20) | 3.72(7) min | β$^−$ | $^{130}$Sb | 0+ | | |
| $^{130m1}$Sn | 1946.88(10) keV | 1946.88(10) keV | 1946.88(10) keV | 1.7(1) min | β$^−$ | $^{130}$Sb | 7− | | |
| $^{130m2}$Sn | 2434.79(12) keV | 2434.79(12) keV | 2434.79(12) keV | 1.501(17) μs | IT | $^{130}$Sn | (10+) | | |
| $^{131}$Sn | 50 | 81 | 130.917053(4) | 56.0(5) s | β$^−$ | $^{131}$Sb | 3/2+ | | |
| $^{131m1}$Sn | 65.1(3) keV | 65.1(3) keV | 65.1(3) keV | 58.4(5) s | β$^−$ | $^{131}$Sb | 11/2− | | |
| $^{131m1}$Sn | 65.1(3) keV | 65.1(3) keV | 65.1(3) keV | 58.4(5) s | IT? | $^{131}$Sn | 11/2− | | |
| $^{131m2}$Sn | 4670.0(4) keV | 4670.0(4) keV | 4670.0(4) keV | 316(5) ns | IT | $^{131}$Sn | (23/2−) | | |
| $^{132}$Sn | 50 | 82 | 131.9178239(21) | 39.7(8) s | β$^−$ | $^{132}$Sb | 0+ | | |
| $^{132m}$Sn | 4848.52(20) keV | 4848.52(20) keV | 4848.52(20) keV | 2.080(16) μs | IT | $^{132}$Sn | 8+ | | |
| $^{133}$Sn | 50 | 83 | 132.9239138(20) | 1.37(7) s | β$^−$ (99.97%) | $^{133}$Sb | 7/2− | | |
| $^{133}$Sn | 50 | 83 | 132.9239138(20) | 1.37(7) s | β$^−$n (.0294%) | $^{132}$Sb | 7/2− | | |
| $^{134}$Sn | 50 | 84 | 133.928680(3) | 0.93(8) s | β$^−$ (83%) | $^{134}$Sb | 0+ | | |
| $^{134}$Sn | 50 | 84 | 133.928680(3) | 0.93(8) s | β$^−$n (17%) | $^{133}$Sb | 0+ | | |
| $^{134m}$Sn | 1247.4(5) keV | 1247.4(5) keV | 1247.4(5) keV | 87(8) ns | IT | $^{132}$Sn | 6+ | | |
| $^{135}$Sn | 50 | 85 | 134.934909(3) | 515(5) ms | β$^−$ (79%) | $^{135}$Sb | 7/2−# | | |
| $^{135}$Sn | 50 | 85 | 134.934909(3) | 515(5) ms | β$^−$n (21%) | $^{134}$Sb | 7/2−# | | |
| $^{135}$Sn | 50 | 85 | 134.934909(3) | 515(5) ms | β$^−$2n? | $^{133}$Sb | 7/2−# | | |
| $^{136}$Sn | 50 | 86 | 135.93970(22)# | 355(18) ms | β$^−$ (72%) | $^{136}$Sb | 0+ | | |
| $^{136}$Sn | 50 | 86 | 135.93970(22)# | 355(18) ms | β$^−$n (28%) | $^{135}$Sb | 0+ | | |
| $^{136}$Sn | 50 | 86 | 135.93970(22)# | 355(18) ms | β$^−$2n? | $^{134}$Sb | 0+ | | |
| $^{137}$Sn | 50 | 87 | 136.94616(32)# | 249(15) ms | β$^−$ (52%) | $^{137}$Sb | 5/2−# | | |
| $^{137}$Sn | 50 | 87 | 136.94616(32)# | 249(15) ms | β$^−$n (48%) | $^{136}$Sb | 5/2−# | | |
| $^{137}$Sn | 50 | 87 | 136.94616(32)# | 249(15) ms | β$^−$2n? | $^{135}$Sb | 5/2−# | | |
| $^{138}$Sn | 50 | 88 | 137.95114(43)# | 148(9) ms | β$^−$ (64%) | $^{138}$Sb | 0+ | | |
| $^{138}$Sn | 50 | 88 | 137.95114(43)# | 148(9) ms | β$^−$n (36%) | $^{137}$Sb | 0+ | | |
| $^{138}$Sn | 50 | 88 | 137.95114(43)# | 148(9) ms | β$^−$2n? | $^{136}$Sb | 0+ | | |
| $^{138m}$Sn | 1344(2) keV | 1344(2) keV | 1344(2) keV | 210(45) ns | IT | $^{138}$Sn | (6+) | | |
| $^{139}$Sn | 50 | 89 | 138.95780(43)# | 120(38) ms | β$^−$ | $^{139}$Sb | 5/2−# | | |
| $^{139}$Sn | 50 | 89 | 138.95780(43)# | 120(38) ms | β$^−$n? | $^{138}$Sb | 5/2−# | | |
| $^{139}$Sn | 50 | 89 | 138.95780(43)# | 120(38) ms | β$^−$2n? | $^{137}$Sb | 5/2−# | | |
| $^{140}$Sn | 50 | 90 | 139.96297(32)# | 50# ms [>550 ns] | β$^−$? | $^{140}$Sb | 0+ | | |
| $^{140}$Sn | 50 | 90 | 139.96297(32)# | 50# ms [>550 ns] | β$^−$n? | $^{139}$Sb | 0+ | | |
| $^{140}$Sn | 50 | 90 | 139.96297(32)# | 50# ms [>550 ns] | β$^−$2n? | $^{138}$Sb | 0+ | | |
| This table header & footer: view ||||||||||
* ↑ $^m$Sn – 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).
* 1 2 3 # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
* ↑ Modes of decay: EC:Electron capture IT:Isomeric transition n:Neutron emission p:Proton emission
* ↑ Bold symbol as daughter – Daughter product is stable.
* ↑ ( ) spin value – Indicates spin with weak assignment arguments.
* ↑ Heaviest known nuclide with more protons than neutrons
* ↑ Heaviest nuclide with equal numbers of protons and neutrons with no observed α decay
* ↑ Believed to decay by β$^+$β$^+$ to $^{112}$Cd
* 1 2 3 4 5 Fission product
* ↑ Believed to undergo β$^−$β$^−$ decay to $^{122}$Te
* ↑ Believed to undergo β$^−$β$^−$ decay to $^{124}$Te with a half-life over 1×10$^{17}$ years
* ↑ Long-lived fission product

## Tin-117m

Tin-117m is a radioisotope of tin. One of its uses is in a particulate suspension to treat canine synovitis (radiosynoviorthesis).

## Tin-121m

Tin-121m ($^{121m}$Sn) is a radioisotope and nuclear isomer of tin with a half-life of 43.9 years.
In a normal thermal reactor, it has a very low fission product yield; thus, this isotope is not a significant contributor to nuclear waste. Fast fission or fission of some heavier actinides will produce tin-121 at higher yields. For example, its yield from uranium-235 is 0.0007% per thermal fission and 0.002% per fast fission.

## Tin-126

Yield, % per fission :
| | Thermal | Fast | 14 MeV |
| $^{232}$Th | not fissile | 0.0481 ± 0.0077 | 0.87 ± 0.20 |
| $^{233}$U | 0.224 ± 0.018 | 0.278 ± 0.022 | 1.92 ± 0.31 |
| $^{235}$U | 0.056 ± 0.004 | 0.0137 ± 0.001 | 1.70 ± 0.14 |
| $^{238}$U | not fissile | 0.054 ± 0.004 | 1.31 ± 0.21 |
| $^{239}$Pu | 0.199 ± 0.016 | 0.26 ± 0.02 | 2.02 ± 0.22 |
| $^{241}$Pu | 0.082 ± 0.019 | 0.22 ± 0.03 | ? |
Tin-126 is a radioisotope of tin and one of the only seven long-lived fission products of uranium and plutonium. While tin-126's half-life of 230,000 years translates to a low specific activity of gamma radiation, its short-lived decay products, two isomers of antimony-126, emit 17 and 40 keV gamma radiation and a 3.67 MeV beta particle on their way to stable tellurium-126, making external exposure to tin-126 a potential concern.
Tin-126 is in the middle of the mass range for fission products. Thermal reactors, which make up almost all current nuclear power plants, produce it at a very low yield (0.056% for $^{235}$U), since slow neutrons almost always fission $^{235}$U or $^{239}$Pu into unequal halves. Fast fission in a fast reactor or nuclear weapon, or fission of some heavy minor actinides such as californium, will produce it at higher yields.
* ANL factsheet