Strontium-90 for research

• Geochronology and archaeology

  Luminescence dating^{2, 3, 4}

  Sr-90/Y-90 sources in TL and OSL readers give the known doses that luminescence ages are measured against.

  More: Luminescence dating

  A luminescence age is the dose a sample absorbed since it was last exposed to light or heat, divided by the yearly dose rate where it lay buried. The reader gives the sample a series of known beta doses and reads its natural signal against the growth curve they make.

  Risø TL/OSL readers often carry a 1.48 GBq Sr-90/Y-90 source that delivers about 0.1 Gy per second. Many quartz grains saturate with a characteristic dose of 30 to 50 Gy, which limits the oldest ages a sample can give.

• Particle physics instrumentation

  Silicon sensor tests^{5, 6}

  Detector groups test silicon sensors with Sr-90 sources, whose energetic Y-90 electrons deposit charge much as collider particles do.

  More: Silicon sensor tests

  A plastic scintillator behind the sensor triggers only on the most energetic electrons, whose charge in the silicon closely matches that of a minimum-ionizing particle. The CMS tracker group measured charge collection this way on sensors before and after irradiation.

  The collected charge follows a Landau distribution. In 300 µm of silicon its most probable value is about 23,000 electrons.

• Radiation protection dosimetry

  Calibrating beta dosimeters^{7, 8}

  Sr-90/Y-90 is one of the ISO 6980 reference beta sources for calibrating beta dosimeters and dose rate meters.

  More: Calibrating beta dosimeters

  Calibration laboratories place the instrument at a fixed distance from a shuttered source. The PTB beta secondary standard BSS 2, with a 460 MBq Sr-90/Y-90 source, gives a nominal dose rate in tissue at 0.07 mm depth of 120 µGy/s at 11 cm and 6 µGy/s at 50 cm.

• Radiation physics

  Beta absorption and thickness gauges^{9, 10}

  Betas stop within a range set by their energy, so the count rate behind an absorber measures its thickness.

  More: Beta absorption and thickness gauges

  Sr-90 betas stop in about 0.7 mm of aluminium and Y-90 betas in about 4 mm, from the Katz and Penfold range-energy relation. A curve of count rate against absorber thickness gives the endpoint energy of each group.

  Industrial nucleonic gauges use Sr-90, among other beta sources, to measure paper, plastic film and aluminium sheet.

• Environmental radioanalysis

  Gross beta counting¹¹

  EPA Method 900.0 prescribes Sr-90 in equilibrium with Y-90 for calibrating gross beta counts of drinking water.

  More: Gross beta counting

  Labs add a Sr-90/Y-90 standard to tap water aliquots, dry them on 2-inch planchets with 0 to 300 mg of residue, and plot counting efficiency against residue weight. Each sample's efficiency is read from that curve.

• Radiochemistry

  Radiostrontium in water^{1, 12, 13}

  Sr-90 in water is measured through its Y-90 daughter, which grows back into purified strontium within two to three weeks.

  More: Radiostrontium in water

  EPA Method 905.0 separates strontium, removes the yttrium, and lets Y-90 grow back in before separating and counting it. Known amounts of Sr-90 standard set the counting efficiencies.

  With its 64.05 hour half-life, Y-90 reaches about 97 percent of the Sr-90 activity two weeks after separation.

• Laboratory quality control

  Daily instrument checks¹⁴

  A long-lived Sr-90/Y-90 check source, counted on each day of use, shows when a counter drifts.

  More: Daily instrument checks

  Labs count the check source at least 20 times to set a central line, then chart each count against warning limits at two standard deviations and control limits at three. A count outside the control limits stops measurements until the problem is found.

  Sr-90/Y-90, with a 2.28 MeV endpoint, is a common beta source for counter calibration. A check source needs a known half-life and enough activity for precise counts, not a traceable certificate.

• Disk check source

  Sr-90/Y-90 sealed in a thin disk

  Counter and survey meter checks

  Feasibility review
• Thin-window source

  Deposit in a capsule behind a thin window

  Detector tests and beta absorption

  Feasibility review
• Wide-area reference source

  Even deposit on a backing plate

  Contamination monitor tests

  Feasibility review
• Standard solution

  Sr-90/Y-90 in dilute acid, in a sealed vial

  Planchet and counter efficiency standards

  Feasibility review

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

Source: IAEA LiveChart of Nuclides, ENSDF evaluation by S. K. Basu and E.A. MCCUTCHAN (literature cutoff 1 March 2020), retrieved 25 September 2026 [1]. Reference values; a manufacturer's certificate states the activity of a specific source.

• ²⁴¹Am

  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.

• ¹³³Ba

  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.

• ¹⁴C

  Carbon-14 for research

  C-14 · Half-life 5,700 years

  The label that sits in a molecule's carbon backbone, for following carbon through cells, animals, plants and soil.

• ¹³⁷Cs

  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.

• ⁵⁷Co

  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.

• ⁶⁰Co

  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.

1. IAEA Nuclear Data Section. LiveChart of Nuclides, Sr-90 and Y-90 decay data (ENSDF evaluations). Retrieved 25 September 2026. www-nds.iaea.org/relnsd/vcharthtml/VChartHTML.html
2. Duller GAT. Luminescence Dating: Guidelines on Using Luminescence Dating in Archaeology. Swindon: English Heritage; 2008. users.aber.ac.uk/ggd/duller_english_heritage_luminescence_dating.pdf
3. Osunkwor E, DeWitt R. Beta dose rate reduction for the built-in 90Sr/90Y sources of Risø TL/OSL automated readers. Ancient TL. 2021;39(2):18-27. doi.org/10.26034/la.atl.2021.553
4. Hu Y, Li B, Jacobs Z. Single-grain quartz OSL characteristics: testing for correlations within and between sites in Asia, Europe and Africa. Methods Protoc. 2020;3(1):2. doi.org/10.3390/mps3010002
5. Adam W, Bergauer T, Blöch D, et al. (Tracker Group of the CMS Collaboration). Experimental study of different silicon sensor options for the upgrade of the CMS Outer Tracker. J Instrum. 2020;15(4):P04017. doi.org/10.1088/1748-0221/15/04/P04017
6. Kramberger G, Wermes N. Semiconductor detectors. In: Particle Data Group, Review of Particle Physics. Int J Mod Phys A. 2026;41(22):2630011. pdg.lbl.gov/2026/reviews/rpp2026-rev-particle-detectors-accel.pdf
7. Ambrosi P, Buchholz G, Helmstädter K. The PTB beta secondary standard BSS 2 for radiation protection. J Instrum. 2007;2(11):P11002. doi.org/10.1088/1748-0221/2/11/P11002
8. International Atomic Energy Agency. Calibration of Radiation Protection Monitoring Instruments. Safety Reports Series No. 16. Vienna: IAEA; 2000. www-pub.iaea.org/MTCD/Publications/PDF/P074_scr.pdf
9. Katz L, Penfold AS. Range-energy relations for electrons and the determination of beta-ray end-point energies by absorption. Rev Mod Phys. 1952;24(1):28-44. doi.org/10.1103/RevModPhys.24.28
10. International Atomic Energy Agency. Technical Data on Nucleonic Gauges. IAEA-TECDOC-1459. Vienna: IAEA; 2005. www-pub.iaea.org/MTCD/Publications/PDF/te_1459_web.pdf
11. U.S. Environmental Protection Agency. Method 900.0: Gross alpha and gross beta radioactivity in drinking water. In: Prescribed Procedures for Measurement of Radioactivity in Drinking Water. EPA-600/4-80-032. Cincinnati: EPA; 1980. www.epa.gov/sites/default/files/2015-06/documents/epa-900.0.pdf
12. U.S. Environmental Protection Agency. Method 905.0: Radioactive strontium in drinking water. In: Prescribed Procedures for Measurement of Radioactivity in Drinking Water. EPA-600/4-80-032. Cincinnati: EPA; 1980. www.epa.gov/sites/default/files/2015-06/documents/epa-905.0.pdf
13. U.S. EPA, NRC, DOE, et al. Multi-Agency Radiological Laboratory Analytical Protocols Manual (MARLAP), Volume II, Chapter 14: Separation techniques. NUREG-1576, EPA 402-B-04-001B. 2004. www.epa.gov/sites/default/files/2015-05/documents/402-b-04-001b-14-final.pdf
14. U.S. EPA, NRC, DOE, et al. Multi-Agency Radiological Laboratory Analytical Protocols Manual (MARLAP), Volume III, Chapter 18: Laboratory quality control. NUREG-1576, EPA 402-B-04-001C. 2004. www.epa.gov/sites/default/files/2015-05/documents/402-b-04-001c-18-final.pdf
15. 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
16. 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
17. U.S. Nuclear Regulatory Commission. 10 CFR 32.18, Manufacture, distribution and transfer of exempt quantities of byproduct material. eCFR, current as of 23 September 2026. www.ecfr.gov/current/title-10/section-32.18

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