Sealed gamma reference sources

Feasibility review

Cobalt-57 for research

The source behind iron Mössbauer spectroscopy, and a 122 keV standard for detectors and cameras.

Half-life
271.7 days
Main gamma
122.1 keV
Decay
Electron capture to Fe-57
Exempt quantity
100 µCi
Request a Co-57 feasibility review

Request a feasibility review for Co-57

No license file needed to ask. A scientist reads every request and replies with the next step.

How ordering works
Co-57 at a glanceIAEA evaluated data
aSIMULATED HPGe RESPONSE050100150110²10⁴Energy (keV)Counts122.1136.514.4Fe K X-raysb06121824050100Time (months)Activity (%)T½ 271.7 d39% left after 1 year
a What a germanium detector records, simulated from the IAEA lines; amber: Mössbauer line. b Activity left after the reference date. Data: IAEA [1]

Mössbauer spectroscopy

Why a 14.4 keV gamma ray matters.

Co-57 decays into an iron-57 state that emits a 14.4 keV gamma ray. Moving the source shifts that energy by a tiny, controlled amount, and iron nuclei in a sample absorb only at their own energies. The resulting spectrum shows how the iron is bonded.

Sources: 2

Mössbauer spectrometerTransmission
Illustrative spectrum of metallic iron. The magnetic field at the iron nucleus splits the absorption into six lines.

Research applications

Where Co-57 does the work.

Figures are simulated examples of each measurement.

  • aSIMULATED−8−4048Velocity (mm/s)TransmissionFe³⁺ high spinFe²⁺ high spinmagnetic, α-Fe₂O₃

    Materials and inorganic chemistry

    Iron oxidation, spin and magnetism2

    Mössbauer spectra tell Fe(II) from Fe(III), high spin from low spin, and reveal magnetic order.

    More: Iron oxidation, spin and magnetism

    Chemists and materials scientists use Co-57 sources to characterize iron compounds, steels, magnetic materials and nanoparticles. The spectrum gives oxidation state, spin state and magnetic environment in one measurement.

  • bSIMULATED−10−50510Velocity (mm/s)Countsjarositehematite

    Planetary science

    Iron minerals on Mars3, 4

    The Spirit and Opportunity rovers carried Co-57 Mössbauer spectrometers to identify iron minerals on Mars.

    More: Iron minerals on Mars

    The miniaturized MIMOS II spectrometer used a Co-57 source to measure rocks and soils in place. At Meridiani Planum it identified jarosite and hematite, evidence that water shaped those rocks.

  • cSIMULATED−2024Velocity (mm/s)TransmissionFe²⁺Fe³⁺

    Earth sciences

    Redox history of rocks and glasses5

    The ratio of ferrous to ferric iron in minerals, glasses and meteorites records how oxidizing their environment was.

    More: Redox history of rocks and glasses

    Geologists and meteoriticists measure iron valence and site occupancy in minerals with Mössbauer spectroscopy, from soils and sediments to volcanic glass and extraterrestrial samples.

  • dSIMULATED101001000Quench time (ms)00.51Fraction of ⁵⁷Fereactantintermediateproduct

    Biochemistry

    Short-lived states of iron enzymes6

    Freeze-quench Mössbauer spectroscopy traps and identifies reactive iron intermediates in enzymes.

    More: Short-lived states of iron enzymes

    Enzymologists freeze a reaction within milliseconds of mixing, then read the iron sites of an iron-57-enriched enzyme with a Co-57 source. The method has identified high-valent iron intermediates in oxygen-activating enzymes.

  • eSIMULATED00.51Co in Co–Mo–S (a.u.)00.51HDS activity (a.u.)

    Catalysis

    Emission spectroscopy inside a catalyst7, 8

    Co-57 built into a cobalt catalyst becomes the source itself and reports on the cobalt sites.

    More: Emission spectroscopy inside a catalyst

    In emission Mössbauer spectroscopy the Co-57 sits in the material under study. Applied to sulfided cobalt-molybdenum hydrodesulfurization catalysts, it revealed the Co-Mo-S phase associated with their activity.

  • fSIMULATED2004006008001000Firing temperature (°C)0.60.91.2Fe³⁺ splitting (mm/s)clay loses water

    Archaeology

    How ancient pottery was fired9, 10

    Iron in fired clay changes with temperature, which helps estimate the firing temperature of ancient ceramics.

    More: How ancient pottery was fired

    Archaeometry studies read Mössbauer and infrared spectra of pottery sherds to estimate how hot ancient kilns ran.

    In clay fired in air, the Fe³⁺ splitting rises as the clay loses the water bound in its structure, then falls as new minerals form.

  • gSIMULATED050100150Energy (keV)110²10⁴Counts122.1136.514.4Fe K X-rays

    Radiation detection

    Low-energy detector calibration1, 11

    Its 122 and 136 keV lines are recommended standards for calibrating gamma-ray detectors at low energy.

    More: Low-energy detector calibration

    Evaluated emission probabilities make Co-57 one of the IAEA's recommended nuclides for energy and efficiency calibration of gamma-ray spectrometers.

  • hSIMULATEDUFOVCFOVhighlowCounts

    Imaging physics

    Gamma camera uniformity12

    Large Co-57 flood sources give an even field for routine uniformity checks of scintillation cameras.

    More: Gamma camera uniformity

    The 122 keV line sits close to the 140 keV line of technetium-99m, so sheet sources check camera uniformity with low-energy collimators in place.

  • iSIMULATED090180270360Days3065100Reading (% of day 0)T½ 271.7 d

    Radionuclide metrology

    Radioactivity calibrator checks13

    Sealed Co-57 reference sources support routine quality control of radioactivity calibrators.

    More: Radioactivity calibrator checks

    Calibrators measure the activity of prepared radioactive samples. Long-lived reference sources such as Co-57 check that their response stays constant over time.

Forms

Co-57 forms researchers ask for

Every source is confirmed with its manufacturer before you order.

  • Mössbauer source

    Co-57 in a metal matrix, commonly rhodium

    Iron-57 Mössbauer spectrometers

    Feasibility review

  • Point or disk source

    Sealed, encapsulated Co-57

    Detector checks and energy calibration

    Feasibility review

  • Flood (sheet) source

    Co-57 sealed in a flat panel

    Camera uniformity checks

    Feasibility review

  • Calibrator reference source

    Sealed vial or syringe geometry

    Calibrator checks

    Feasibility review

Activity, certificate and lead time are set with the manufacturer at quote.

Before you order

Plan for decay and licensing.

Plan around decay

Co-57 has a half-life of 271.7 days and loses about 1.8 percent of its activity each week. Ask for the activity you need on the day you start using it.

Activity remaining after
  1. 30 days92.6%
  2. 90 days79.5%
  3. 6 months63.2%
  4. 1 year39.4%

Licensing

Exempt quantityNeeds a license100 µCi
Activity of one source, log scale

A single Co-57 source at or below 100 µCi is an exempt quantity under 10 CFR 30.71, Schedule B. Above that, your institution needs a license that covers it.

  • Combining exempt sources to exceed the limit is not covered.
  • Agreement States apply equivalent rules. Your RSO reviews the exact source before you order.

Sources: 14, 15

Start a request

Request a feasibility review for Co-57.

No license file needed to ask. A scientist reads every request and replies with the next step.

  1. Name the instrumentThe spectrometer, camera or detector sets the source form.
  2. Give a reference dateState the activity you need on the day you start using it.
  3. Plan the next sourceActivity halves about every nine months.
  1. 01Need
  2. 02Details
  3. 03Contact
Where are you starting?

You get Feasibility reply and a candidate supplier path

Decay data

Co-57 decay data

Decay schemeCo-57 to Fe-57
57Co271.7 dQ 836.4 keV57Fe136.4714.410EC 100%136.47 keV gamma ray, 10.7 per 100 decays136.4710.7%122.06 keV gamma ray, 85.6 per 100 decays122.0685.6%14.41 keV gamma ray, 9.16 per 100 decays14.419.16%
14.41 keV: Mössbauer lineEnergies in keV, with emission probability per decay. Levels not to scale. Data: IAEA [1]
Half-life
271.74 days ± 0.06
Decay mode
Electron capture (100%)
Daughter
Fe-57
Decay energy (Q)
836.4 keV
Co-57 emissions
RadiationEnergy (keV)Per 100 decays
Gamma14.419.16
Gamma122.0685.6
Gamma136.4710.7
Gamma692.410.149
X-ray6.3916.8
X-ray6.432.9
X-ray7.086.8

Source: IAEA LiveChart of Nuclides, ENSDF evaluation by M. R. BHAT (literature cutoff 24 September 1998), retrieved 25 September 2026 [1]. Reference values; a manufacturer's certificate states the activity of a specific source.

Questions, answered

Co-57 questions

How long does a Co-57 source last?

Its activity halves every 271.7 days, so about 39 percent remains after one year. How long a source stays useful depends on the lowest activity your measurement can use.

Can we buy Co-57 without a radioactive materials license?

For small sources, possibly. A single Co-57 source at or below 100 microcuries is an exempt quantity under 10 CFR 30.71, and a distributor licensed under 10 CFR 32.18 can supply it to users without a license. Larger sources need a license that covers them. Your RSO decides how your institution handles each case.

What activity should we ask for?

State the activity you need at a reference date close to first use, and the instrument or measurement it serves. We confirm a matching source and certificate with the manufacturer before you order.

Does the certificate state the activity on delivery?

It states the activity at the manufacturer's reference date. We convert it to your delivery or first-use date on the quote, and the chart at the top of this page shows how the activity falls.

Can you supply a Mössbauer source?

Send the request with your spectrometer, source holder and the activity you need. Mössbauer sources are a feasibility review until we confirm a supplier and configuration.

Can a decayed source be returned?

Some manufacturers take back their own sealed sources. A return is a separate shipment with its own RSO and shipping review, so ask us before the source reaches the end of its use.

More isotopes

  • Barium-133 for research

    Ba-133 · Half-life 10.55 years

    Gamma lines from 81 to 384 keV and cesium X-rays near 31 keV: a standard for low- and mid-energy calibration.

  • Cesium-137 for research

    Cs-137 · Half-life 30.08 years

    One gamma line at 662 keV and a 30-year half-life: a long-lived reference for detector and calibrator checks.

  • Cobalt-60 for research

    Co-60 · Half-life 5.27 years

    Two gamma rays in cascade, at 1173 and 1332 keV: a standard for high-energy calibration and coincidence work.

  • Europium-152 for research

    Eu-152 · Half-life 13.52 years

    Gamma lines from 122 to 1408 keV in one source: a standard for calibrating germanium detectors across their range.

  • Americium-241 for research

    Am-241 · Half-life 432.6 years

    Alpha particles near 5.49 MeV and a 59.5 keV gamma ray, from one long-lived source.

  • Iodine-125 for research

    I-125 · Half-life 59.41 days

    A high specific activity label for proteins, peptides and receptor ligands, counted in a gamma counter.

Sources

References

  1. IAEA Nuclear Data Section. LiveChart of Nuclides, Co-57 decay data (ENSDF evaluation). Retrieved 25 September 2026. www-nds.iaea.org/relnsd/vcharthtml/VChartHTML.html
  2. Gütlich P, Bill E, Trautwein AX. Mössbauer Spectroscopy and Transition Metal Chemistry: Fundamentals and Applications. Berlin: Springer; 2011. doi.org/10.1007/978-3-540-88428-6
  3. Klingelhöfer G, Morris RV, Bernhardt B, et al. Athena MIMOS II Mössbauer spectrometer investigation. J Geophys Res Planets. 2003;108(E12). doi.org/10.1029/2003JE002138
  4. Klingelhöfer G, Morris RV, Bernhardt B, et al. Jarosite and hematite at Meridiani Planum from Opportunity's Mössbauer spectrometer. Science. 2004;306(5702):1740-1745. doi.org/10.1126/science.1104653
  5. Dyar MD, Agresti DG, Schaefer MW, et al. Mössbauer spectroscopy of earth and planetary materials. Annu Rev Earth Planet Sci. 2006;34:83-125. doi.org/10.1146/annurev.earth.34.031405.125049
  6. Krebs C, Bollinger JM Jr. Freeze-quench 57Fe-Mössbauer spectroscopy: trapping reactive intermediates. Photosynth Res. 2009;102(2-3):295. doi.org/10.1007/s11120-009-9406-6
  7. Topsøe H, et al. In situ Mössbauer emission spectroscopy studies of unsupported and supported sulfided Co-Mo hydrodesulfurization catalysts: evidence for and nature of a Co-Mo-S phase. J Catal. 1981;68(2):433-452. doi.org/10.1016/0021-9517(81)90114-7
  8. Wivel C, Candia R, Clausen BS, Mørup S, Topsøe H. On the catalytic significance of a Co-Mo-S phase in Co-Mo/Al2O3 hydrodesulfurization catalysts: combined in situ Mössbauer emission spectroscopy and activity studies. J Catal. 1981;68(2):453-463. doi.org/10.1016/0021-9517(81)90115-9
  9. Venkatachalapathy R, Sridharan T, Dhanapandian S, et al. Determination of firing temperature of ancient potteries by means of infrared and Mössbauer studies. Spectrosc Lett. 2002;35(6):769-779. doi.org/10.1081/SL-120016279
  10. Häusler W. Firing of clays studied by X-ray diffraction and Mössbauer spectroscopy. Hyperfine Interact. 2004;154(1-4):121-141. doi.org/10.1023/B:HYPE.0000032075.92893.57
  11. International Atomic Energy Agency. X-ray and Gamma-ray Standards for Detector Calibration. IAEA-TECDOC-619. Vienna: IAEA; 1991. www-pub.iaea.org/MTCD/Publications/PDF/te_619_web.pdf
  12. International Atomic Energy Agency. IAEA Quality Control Atlas for Scintillation Camera Systems. Vienna: IAEA; 2003. www-pub.iaea.org/MTCD/Publications/PDF/Pub1141_web.pdf
  13. International Atomic Energy Agency. Quality Assurance for Radioactivity Measurement in Nuclear Medicine. Technical Reports Series No. 454. Vienna: IAEA; 2006. www-pub.iaea.org/MTCD/Publications/PDF/TRS454_web.pdf
  14. U.S. Nuclear Regulatory Commission. 10 CFR 30.71, Schedule B (exempt quantities). eCFR, current as of 22 September 2026. www.ecfr.gov/current/title-10/section-30.71
  15. U.S. Nuclear Regulatory Commission. 10 CFR 30.18, Exempt quantities. eCFR, current as of 22 September 2026. www.ecfr.gov/current/title-10/section-30.18

Technical review by ConductScience, 25 September 2026. Next review 25 September 2027.

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