Element 27 — Cobalt (Co) — Z = 27

Notation: mass number as a left superscript (e.g., ⁶⁰Co).
Columns: Isotope | Z | A | Stable? | Half‑life | Decay mode(s) | Daughter | Radiation | Origin | Uses | Notes.
Backbone data: half‑lives, branches, and daughters from the evaluated Isotopes of cobalt table (ENSDF/AME/NUBASE compilation). Authoritative decay details (e.g., ⁶⁰Co, ⁵⁶Co branching; ⁵⁷Co γ‑lines; ⁵⁸Co practice) and application notes are cited inline. (Wikipedia)

Isotope	Z	A	Stable?	Half‑life	Decay mode(s)	Daughter	Radiation	Origin	Uses	Notes
⁵⁰Co	27	50	No	38.8(2) ms	β⁺,p 70.5%; β⁺ 29.5%; β⁺,2p?	⁴⁹Mn; ⁵⁰Fe; ⁴⁸Cr	β⁺; delayed p/2p	Synthetic	Proton‑rich decay studies	— (Wikipedia)
⁵¹Co	27	51	No	68.8(19) ms	β⁺ 96.2%; β⁺,p < 3.8%	⁵¹Fe; ⁵⁰Mn	β⁺; delayed p	Synthetic	β⁺/p systematics	— (Wikipedia)
⁵²Co	27	52	No	111.7(21) ms	β⁺ (± β⁺,p?)	⁵²Fe; (⁵¹Mn)	β⁺; delayed p?	Synthetic	Structure/decay	⁵²ᵐCo 102(5) ms (IT/β⁺). (Wikipedia)
⁵³Co	27	53	No	244.6(28) ms	β⁺	⁵³Fe	β⁺	Synthetic	β⁺ spectroscopy	⁵³ᵐCo 250(10) ms (β⁺ ~98.5%, p ~1.5%). (Wikipedia)
⁵⁴Co	27	54	No	193.27(6) ms	β⁺	⁵⁴Fe	β⁺	Synthetic	Reaction studies	⁵⁴ᵐCo 1.48(2) min (β⁺). (Wikipedia)
⁵⁵Co	27	55	No	17.53(3) h	β⁺ → ⁵⁵Fe	⁵⁵Fe	β⁺; 511 keV γ	Synthetic (cyclotron)	PET research (e.g., ⁵⁵Co‑DOTATATE/EDTA); radiochemistry tracer	High β⁺ yield (~76%); active theranostic research with ⁵⁸ᵐCo. (ScienceDirect, PubMed Central)
⁵⁶Co	27	56	No	77.236(26) d	EC 80.42%; β⁺ 19.58% → ⁵⁶Fe*	⁵⁶Fe	γ up to ~3.6 MeV (incl. 847 & 1238 keV); positrons	Synthetic (⁵⁶Fe(p,n))	γ‑calibration; SN light‑curve physics (⁵⁶Ni→⁵⁶Co→⁵⁶Fe)	Branching and lines per LNHB; SN 1987A/2014J γ detections. (LNHB, Lawrence Berkeley National Laboratory, arXiv, Astrophysics Data System)
⁵⁷Co	27	57	No	271.811(32) d	EC → ⁵⁷Fe (100%)	⁵⁷Fe	γ 122 & 136 keV; 14.4 keV feeding Mössbauer	Synthetic	Mössbauer source for ⁵⁷Fe; detector calibration; historical B‑12 tests	Decay lines/usage sheets. (Gamma-ray Spectrometry Catalog, HPS Chapters)
⁵⁸Co	27	58	No	70.844(20) d	EC 85.21%; β⁺ 14.79% → ⁵⁸Fe	⁵⁸Fe	γ ~811 keV (≈99%); 511 keV (β⁺)	Activation & cyclotron	Activation tracer, γ‑calibration; radionuclidic impurity in ⁵⁵Co production	Safety sheet and IAEA production card. (Stanford Environmental Health & Safety, IAEA Nuclear Data Services, Frontiers)
⁵⁹Co	27	59	Stable	—	—	—	—	Natural (100%)	NMR ref nucleus (⁵⁹Co‑NMR); isotope standards	Mononuclidic element. (Winter Group)
⁶⁰Co	27	60	No	5.2714(6) y	β⁻ → ⁶⁰Ni (100%)	⁶⁰Ni	γ 1173 & 1332 keV (nearly 100%)	Synthetic; trace cosmogenic	Radiotherapy (legacy tele‑Co); industrial radiography; sterilization/irradiators; γ‑calibration	LNHB decay data; KAERI card; safety/industry briefs. (LNHB, KAERI Atomic Data Center, Washington State Department of Health, Office of Science)
⁶¹Co	27	61	No	1.649(5) h	β⁻ → ⁶¹Ni	⁶¹Ni	β⁻; γ (from ⁶¹Ni*)	Synthetic	Activation/γ‑spec	— (Wikipedia)
⁶²Co	27	62	No	1.54(10) min	β⁻ → ⁶²Ni	⁶²Ni	β⁻; γ	Synthetic	Fast β⁻ studies	⁶²ᵐCo 13.86(9) min (β⁻ > 99.5%). (Wikipedia)
⁶³Co	27	63	No	26.9(4) s	β⁻ → ⁶³Ni	⁶³Ni	β⁻	Synthetic	β/γ spectroscopy	— (Wikipedia)
⁶⁴Co	27	64	No	300(30) ms	β⁻ → ⁶⁴Ni	⁶⁴Ni	β⁻	Synthetic	Structure	⁶⁴ᵐCo ≈ 300 ms (IT/β⁻?). (Wikipedia)
⁶⁵Co	27	65	No	1.16(3) s	β⁻ → ⁶⁵Ni	⁶⁵Ni	β⁻	Synthetic	β‑decay mapping	— (Wikipedia)
⁶⁶Co	27	66	No	194(17) ms	β⁻ → ⁶⁶Ni; β⁻,n? → ⁶⁵Ni	⁶⁶Ni; ⁶⁵Ni	β⁻; delayed n?	Synthetic	β‑delayed‑n limits	Isomers ⁶⁶ᵐ₁Co 824 ns; ⁶⁶ᵐ₂Co > 100 µs (IT). (Wikipedia)
⁶⁷Co	27	67	No	329(28) ms	β⁻ → ⁶⁷Ni; β⁻,n? → ⁶⁶Ni	⁶⁷Ni; ⁶⁶Ni	β⁻; delayed n?	Synthetic	Shell evolution	⁶⁷ᵐCo 496(33) ms (IT/β⁻). (Wikipedia)
⁶⁸Co	27	68	No	200(20) ms	β⁻ → ⁶⁸Ni; β⁻,n? → ⁶⁷Ni	⁶⁸Ni; ⁶⁷Ni	β⁻; delayed n?	Synthetic	Dripline approach	⁶⁸ᵐ₁Co 1.6(3) s (β⁻, n > 2.6%); ⁶⁸ᵐ₂Co 101(10) ns (IT). (Wikipedia)
⁶⁹Co	27	69	No	180(20) ms	β⁻ → ⁶⁹Ni; β⁻,n? → ⁶⁸Ni	⁶⁹Ni; ⁶⁸Ni	β⁻; delayed n?	Synthetic	β‑n statistics	⁶⁹ᵐCo 750(250) ms. (Wikipedia)
⁷⁰Co	27	70	No	508(7) ms	β⁻ → ⁷⁰Ni; β⁻,n?/2n? → ⁶⁹/⁶⁸Ni	⁷⁰Ni	β⁻; delayed n/2n?	Synthetic	β/γ spectroscopy	⁷⁰ᵐCo 112(7) ms (β⁻; IT?). (Wikipedia)
⁷¹Co	27	71	No	80(3) ms	β⁻ 97% → ⁷¹Ni; β⁻,n 3% → ⁷⁰Ni	⁷¹Ni; ⁷⁰Ni	β⁻; delayed n	Synthetic	β‑delayed‑n benchmark	— (Wikipedia)
⁷²Co	27	72	No	51.5(3) ms	β⁻ < 96% → ⁷²Ni; β⁻,n > 4% (…2n?)	⁷²Ni; ⁷¹/⁷⁰Ni	β⁻; delayed n	Synthetic	Frontier mapping	⁷²ᵐCo 47.8(5) ms. (Wikipedia)
⁷³Co	27	73	No	42.0(8) ms	β⁻ 94% → ⁷³Ni; β⁻,n 6% → ⁷²Ni (…2n?)	⁷³Ni; ⁷²/⁷¹Ni	β⁻; delayed n	Synthetic	Frontier mapping	— (Wikipedia)
⁷⁴Co	27	74	No	31.3(13) ms	β⁻ 82% → ⁷⁴Ni; β⁻,n 18% → ⁷³Ni (…2n?)	⁷⁴Ni; ⁷³/⁷²Ni	β⁻; delayed n	Synthetic	Frontier mapping	— (Wikipedia)
⁷⁵Co	27	75	No	26.5(12) ms	β⁻ > 84% → ⁷⁵Ni; β⁻,n < 16% → ⁷⁴Ni (…2n?)	⁷⁵Ni; ⁷⁴/⁷³Ni	β⁻; delayed n	Synthetic	Frontier mapping	— (Wikipedia)
⁷⁶Co	27	76	No	23(6) ms	β⁻ → ⁷⁶Ni; β⁻,n?/2n? → ⁷⁵/⁷⁴Ni	⁷⁶Ni; ⁷⁵/⁷⁴Ni	β⁻; delayed n?	Synthetic	Edge‑of‑stability tests	Isomers: ⁷⁶ᵐ₁Co 16(4) ms; ⁷⁶ᵐ₂Co 2.99(27) µs (IT). (Wikipedia)
⁷⁷Co	27	77	No	15(6) ms	β⁻ → ⁷⁷Ni; β⁻,n?/2n?/3n?	⁷⁷Ni; ⁷⁶/⁷⁵/⁷⁴Ni	β⁻; delayed n	Synthetic	Extreme neutron‑rich	Trend/limits in evaluation. (Wikipedia)
⁷⁸Co	27	78	No	≈ 11 ms (#; > 410 ns)	β⁻? → ⁷⁸Ni	⁷⁸Ni	β⁻ (expected)	Synthetic	Most neutron‑rich Co	Trend‑evaluated (#). (Wikipedia)

Radiation key: β⁺/EC → positrons + annihilation γ at 511 keV and/or characteristic X‑rays/Auger (for EC); β⁻ (electron); β⁺,p/2p = β⁺ with delayed proton(s); β⁻, n/2n/3n = β⁻ with 1/2/3 delayed neutron(s); IT = isomeric γ.

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Applied & research highlights (Cobalt)

• ⁶⁰Co (5.27 y, β⁻) is a workhorse γ source: industrial radiography, sterilization/irradiation, and legacy tele‑therapy; its nearly monoenergetic 1173/1332 keV γ‑pair underpins detector calibration standards. (Washington State Department of Health, Office of Science, LNHB)
• ⁵⁷Co (271.8 d, EC → ⁵⁷Fe) provides the 122 & 136 keV lines feeding the 14.4 keV Mössbauer transition in iron — the classic ⁵⁷Fe Mössbauer source and a sealed‑source γ‑calibrator. (Gamma-ray Spectrometry Catalog)
• ⁵⁶Co (77.2 d, EC/β⁺) gives intense lines (e.g., 847/1238 keV) and figures centrally in supernova physics (⁵⁶Ni→⁵⁶Co→⁵⁶Fe) with direct γ‑line detections (SN 1987A; SN 2014J). (LNHB, Astrophysics Data System, arXiv)
• ⁵⁵Co (17.5 h, β⁺) is a promising PET radionuclide (e.g., ⁵⁵Co‑DOTATATE), with current radiocobalt theranostics pairing to ⁵⁸ᵐCo (Auger therapy). Production/separation focus: minimizing ⁵⁶Co/⁵⁸gCo impurities. (ScienceDirect, PubMed Central, Frontiers)
• ⁵⁸Co (70.86 d) is a common activation product and γ‑calibration line (~811 keV); its control is important during ⁵⁵Co cyclotron productions. (IAEA Nuclear Data Services, Stanford Environmental Health & Safety)

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Sources & cross‑checks

• Isotopes of cobalt — per‑nuclide half‑lives, decay modes/branches, daughters; range A = 50–78; counts and isomer notes. (Wikipedia)
• IAEA LiveChart / NDS — authoritative ENSDF decay & structure datasets. (IAEA Nuclear Data Services)
• ⁶⁰Co: LNHB/DDEP decay tables (t½ = 5.271 y; γ 1173/1332 keV); KAERI nuclide card; applied usage fact sheets (industrial radiography/sterilization). (LNHB, KAERI Atomic Data Center, Washington State Department of Health)
• ⁵⁶Co: LNHB tables (EC/β⁺ branching; high‑energy γ set) and γ‑line detections in SN 1987A/SN 2014J. (LNHB, Astrophysics Data System, arXiv)
• ⁵⁷Co: INL γ‑intensities sheet; safety datasheet with line list and half‑life. (Gamma-ray Spectrometry Catalog, HPS Chapters)
• ⁵⁵Co PET: production/chemistry review and human/animal imaging with ⁵⁵Co‑labelled agents; current theranostic overview. (ScienceDirect, PubMed Central, Frontiers)
• ⁵⁸Co: IAEA medical production card (main 810.8 keV γ) and university RSDS (t½ = 70.86 d). (IAEA Nuclear Data Services, Stanford Environmental Health & Safety)

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Next: Nickel — Ni (Z = 28).

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