Sealed gamma reference sources

Feasibility review

Europium-152 for research

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

Half-life
13.52 years
Main gamma
121.8 keV
Decay
Electron capture and beta plus to Sm-152; beta minus to Gd-152
Exempt quantity
1 µCi
Request an Eu-152 feasibility review

Request a feasibility review for Eu-152

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

How ordering works
Eu-152 at a glanceIAEA evaluated data
aSIMULATED HPGe RESPONSE0500100015002000110²10⁴Energy (keV)Counts121.8344.31408Sm K X-raysb0102030050100Time (years)Activity (%)T½ 13.52 y
a What a germanium detector records, simulated from the IAEA lines; amber: Strongest gamma line. b Activity left after the reference date. Data: IAEA [1]

Research applications

Where Eu-152 does the work.

Figures are simulated examples of each measurement.

  • aSIMULATED0500100015002000Energy (keV)110²10⁴Counts121.8344.31408Sm K X-rays

    Radiation detection

    Efficiency calibration from 122 to 1408 keV1, 2

    Its many gamma lines, each with an evaluated emission probability, calibrate a germanium detector across its range in one measurement.

    More: Efficiency calibration from 122 to 1408 keV

    The IAEA lists Eu-152 among its recommended calibration nuclides, and its evaluation of the emission probabilities drew on 35 sets of spectral data.

  • bSIMULATED01000Energy (keV)00.511.5FWHM (keV)noise 0.33 keVFano factor 0.079

    Detector physics

    Resolution across energy3, 4

    Its lines from 122 to 1408 keV show how a germanium detector's resolution grows with energy.

    More: Resolution across energy

    Resolution combines electronic noise with charge-carrier statistics that grow as the square root of energy. For GERDA's detectors, a fit gave 331 eV of noise and a Fano factor of 0.079, leaving out a third term from incomplete charge collection.

    A 2024 characterization of a germanium detector measured its energy calibration, resolution and efficiency with point sources that included Eu-152.

  • cSIMULATED048Time difference (ns)110²10⁴CoincidencespromptT½ 1.403 ns

    Nuclear physics

    Fast timing on a 1.4 ns level1, 5, 6

    The 121.8 keV level of samarium-152 lives long enough to measure directly, so Eu-152 tests fast-timing detector arrays.

    More: Fast timing on a 1.4 ns level

    Coincidences between a feeding gamma ray, such as 244.7 keV, and the 121.8 keV gamma ray give a time spectrum whose slope is the level's lifetime. The IAEA half-life is 1.403 ns.

    At the NSCL, sixteen lanthanum bromide detectors measured a mean lifetime of 2030 ps against the known 2024 ps, and known lifetimes in Sm-152 and Gd-152 set the array's time-walk curve. An eight-detector array at iThemba LABS measured the half-life as 1.394 ns.

  • dSIMULATED5010020050010002000Energy (keV)0.1110Lead µ/ρ (cm²/g)K edge 88 keVEu-152 lines

    Radiation shielding

    Attenuation from 122 to 1408 keV7, 8, 9

    One Eu-152 source gives attenuation coefficients at many energies across the gamma range.

    More: Attenuation from 122 to 1408 keV

    Shielding studies place the sample in a narrow beam between the source and a germanium detector, and compare the measured coefficients with XCOM values.

    One study of polymer composites used the Eu-152 lines alone, from 121.78 to 1408.01 keV, and found the measurements in line with calculation.

Forms

Eu-152 forms researchers ask for

Every source is confirmed with its manufacturer before you order.

  • Point or disk source

    Sealed, encapsulated Eu-152

    Energy and efficiency calibration, timing tests

    Feasibility review

  • Marinelli beaker source

    Eu-152 in a matrix that fits over the detector

    Efficiency calibration for volume samples

    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

Eu-152 has a half-life of 13.52 years and loses about 0.1 percent of its activity each week. Ask for the activity you need on the day you start using it.

Activity remaining after
  1. 1 year95%
  2. 5 years77.4%
  3. 10 years59.9%
  4. 20 years35.9%

Licensing

Exempt quantityNeeds a license1 µCi
Activity of one source, log scale

A single Eu-152 source at or below 1 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: 10, 11

Start a request

Request a feasibility review for Eu-152.

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

  1. Name the measurementCalibration geometry, detector and energy range set 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 13.5 years.
  1. 01Need
  2. 02Details
  3. 03Contact
Where are you starting?

You get Feasibility reply and a candidate supplier path

Decay data

Eu-152 decay data

Decay schemeEu-152 to Sm-152 and Gd-152
152Eu13.52 yQ 1874.5 keVQ 1818.8 keV152Sm152Gd1529.81233.861085.84121.7801434.021123.19755.4344.28024.8%21.5%17.1%EC, β+ 72.08%13.7%8.24%2.43%β− 27.92%1408.01 keV gamma ray, 20.9 per 100 decays1408.011112.08 keV gamma ray, 13.7 per 100 decays1112.08964.06 keV gamma ray, 14.5 per 100 decays964.06121.78 keV gamma ray, 28.5 per 100 decays121.781089.74 keV gamma ray, 1.73 per 100 decays1089.74778.9 keV gamma ray, 12.9 per 100 decays778.9411.12 keV gamma ray, 2.24 per 100 decays411.12344.28 keV gamma ray, 26.6 per 100 decays344.28
152Eu13.52 yQ 1874.5 keV152Sm1529.81233.861085.84121.78024.8%21.5%17.1%EC, β+ 72.08%1408.01 keV gamma ray, 20.9 per 100 decays1408.011112.08 keV gamma ray, 13.7 per 100 decays1112.08964.06 keV gamma ray, 14.5 per 100 decays964.06121.78 keV gamma ray, 28.5 per 100 decays121.78152Eu13.52 yQ 1818.8 keV152Gd1434.021123.19755.4344.28013.7%8.24%2.43%β− 27.92%1089.74 keV gamma ray, 1.73 per 100 decays1089.74778.9 keV gamma ray, 12.9 per 100 decays778.9411.12 keV gamma ray, 2.24 per 100 decays411.12344.28 keV gamma ray, 26.6 per 100 decays344.28
121.78 keV: Strongest gamma lineEnergies in keV, with emission probability per decay. Levels not to scale. Data: IAEA [1]
Half-life
13.517 years ± 0.009
Decay mode
Electron capture and beta plus (72.08%), Beta minus (27.92%)
Daughters
Sm-152, Gd-152
Decay energy (Q)
1874.5 keV (EC, β+), 1818.8 keV (β−)
Eu-152 emissions
RadiationEnergy (keV)Per 100 decays
Beta695.7 max, 221.7 mean13.7
Beta1474.6 max, 535.5 mean8.24
Beta384.9 max, 112.3 mean2.43
Beta175.5 max, 47.4 mean1.83
Beta1063.5 max, 364.7 mean0.913
Beta888.4 max, 295.1 mean0.284
Beta709.7 max, 226.9 mean0.264
Beta213.3 max, 58.5 mean0.107
Gamma121.7828.5
Gamma244.77.55
Gamma295.940.44
Gamma329.410.121
Gamma344.2826.6
Gamma367.790.859
Gamma411.122.24
Gamma416.020.109
Gamma443.962.83
Gamma444.010.298
Gamma488.680.414
Gamma503.470.152
Gamma563.990.494
Gamma566.440.131
Gamma586.260.455
Gamma656.490.144
Gamma674.640.169
Gamma678.620.473
Gamma688.670.856
Gamma719.350.25
Gamma764.880.189
Gamma778.912.9
Gamma810.450.317
Gamma841.570.168
Gamma867.384.23
Gamma919.340.419
Gamma926.310.272
Gamma963.370.14
Gamma964.0614.5
Gamma1005.270.659
Gamma10840.245
Gamma1085.8410.1
Gamma1089.741.73
Gamma1109.180.189
Gamma1112.0813.7
Gamma1212.951.42
Gamma1249.940.187
Gamma1292.780.101
Gamma1299.141.63
Gamma1408.0120.9
Gamma1457.640.497
Gamma1528.10.279
X-ray6.3514
X-ray39.5220.9
X-ray40.1237.8
X-ray45.5211.8
X-ray4614.8

Source: IAEA LiveChart of Nuclides, ENSDF evaluation by M. J. MARTIN (literature cutoff 31 August 2013), retrieved 25 September 2026 [1]. Reference values; a manufacturer's certificate states the activity of a specific source.

Questions, answered

Eu-152 questions

How long does an Eu-152 source last?

Its activity halves every 13.52 years, so about 95 percent remains after one year. How long a source stays useful depends on the lowest activity your measurement can use.

Can we buy Eu-152 without a radioactive materials license?

For very small sources, possibly. A single Eu-152 source at or below 1 microcurie 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.

Why does an Eu-152 spectrum hold lines of two daughters?

Eu-152 decays by electron capture and beta plus to samarium-152 in 72.08 percent of decays, and by beta minus to gadolinium-152 in the other 27.92 percent. Both daughters are left in excited states, so the spectrum shows both sets of gamma lines.

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 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-57 for research

    Co-57 · Half-life 271.7 days

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

  • 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.

  • 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, Eu-152 decay data and Sm-152 level data (ENSDF evaluation). Retrieved 25 September 2026. www-nds.iaea.org/relnsd/vcharthtml/VChartHTML.html
  2. 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
  3. GERDA Collaboration, Agostini M, Bakalyarov AM, et al. Characterization of 30 76Ge enriched Broad Energy Ge detectors for GERDA Phase II. Eur Phys J C. 2019;79(11):978. doi.org/10.1140/epjc/s10052-019-7353-8
  4. Hafızoğlu N. Efficiency and energy resolution of gamma spectrometry system with HPGe detector depending on variable source-to-detector distances. Eur Phys J Plus. 2024;139(2):134. doi.org/10.1140/epjp/s13360-024-04903-y
  5. Longfellow B, Bender PC, Belarge J, et al. Commissioning of the LaBr3(Ce) detector array at the National Superconducting Cyclotron Laboratory. Nucl Instrum Methods Phys Res A. 2019;916:141-147. doi.org/10.1016/j.nima.2018.10.215
  6. Msebi L, Ingeberg VW, Jones P, et al. A fast-timing array of 2" x 2" LaBr3:Ce detectors for lifetime measurements of excited nuclear states. Nucl Instrum Methods Phys Res A. 2022;1026:166195. doi.org/10.1016/j.nima.2021.166195
  7. Alharshan G, Aloraini D, Elzaher M, et al. A comparative study between nano-cadmium oxide and lead oxide reinforced in high density polyethylene as gamma rays shielding composites. Nucl Technol Radiat Prot. 2020;35(1):42-49. doi.org/10.2298/NTRP2001042A
  8. Cinan ZM, Erol B, Baskan T, et al. Radiation shielding tests of crosslinked polystyrene-b-polyethyleneglycol block copolymers blended with nanostructured selenium dioxide and boron nitride particles. Nanomaterials. 2022;12(3):297. doi.org/10.3390/nano12030297
  9. Hubbell JH, Seltzer SM. Tables of X-Ray Mass Attenuation Coefficients and Mass Energy-Absorption Coefficients (version 1.4). NIST Standard Reference Database 126. Gaithersburg, MD: National Institute of Standards and Technology; 2004. physics.nist.gov/PhysRefData/XrayMassCoef/
  10. U.S. Nuclear Regulatory Commission. 10 CFR 30.71, Schedule B (exempt quantities). eCFR, current as of 23 September 2026. www.ecfr.gov/current/title-10/section-30.71
  11. U.S. Nuclear Regulatory Commission. 10 CFR 30.18, Exempt quantities. eCFR, current as of 23 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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