| Isotope | HalfLife | Decay | PrimaryGammas_keV | PrimaryFrequencies_Hz | AtmosphericForm | Atmosphere_Notes |
|---|---|---|---|---|---|---|
| ³H | 12.32 y | β⁻ (Emax 18.6 keV), no γ | H₂O/HTO vapor, water | Cosmogenic & reactor; mixes with water; β soft, no penetrating γ | ||
| ¹⁴C | 5,730 y | β⁻ (Emax 156 keV), no γ | CO₂ (atmosphere), organics | Cosmogenic ¹⁴C; used in dating; no primary γ | ||
| ²²Na | 2.602 y | β⁺/EC → 1274.5 keV γ + 2×511 keV | 511.0, 1274.5 | 511.0 keV → 1.236e+20 Hz; 1274.5 keV → 3.082e+20 Hz | solid/aerosol source | Activation; PET calibration line at 511 keV |
| ⁴⁰K | 1.248×10⁹ y | β⁻/EC; 1460.8 keV γ (10.7%) | 1460.8 | 1460.8 keV → 3.532e+20 Hz | crustal/particulate | Natural background; strong environmental γ line |
| ³⁹Ar | 269 y | β⁻ (no principal γ) | noble gas (Ar) | Cosmogenic; groundwater & ice dating; β emits weak bremsstrahlung | ||
| ⁴¹Ar | 1.83 h | β⁻; 1293.6 keV γ | 1293.6 | 1293.6 keV → 3.128e+20 Hz | noble gas (Ar) | Neutron activation product in reactors/air; airborne γ detectable |
| ⁸⁵Kr | 10.76 y | β⁻; weak γ ~514 keV | 514.0 | 514.0 keV → 1.243e+20 Hz | noble gas (Kr) | Reprocessing tracer; long-range atmospheric transport |
| ²²²Rn | 3.82 d | α; progeny γ via ²¹⁴Pb/²¹⁴Bi | 295.2, 351.9, 609.3, 1120.3, 1764.5 | 295.2 keV → 7.138e+19 Hz; 351.9 keV → 8.509e+19 Hz; 609.3 keV → 1.473e+20 Hz; 1120.3 keV → 2.709e+20 Hz; 1764.5 keV → 4.267e+20 Hz | noble gas (Rn) | Emanates from soil; daughters attach to aerosols; key γ lines from ²¹⁴Pb/²¹⁴Bi |
| ⁹⁰Sr | 28.8 y | β⁻ (pure); no γ | aerosol/particulate | Fission product; bone seeker; no primary γ | ||
| ⁹⁰Y | 64.1 h | β⁻ (Emax 2.28 MeV); no γ | aerosol/particulate | Daughter of ⁹⁰Sr; therapeutic β emitter | ||
| ¹³¹I | 8.02 d | β⁻; 364.5 keV γ (primary) | 364.5 | 364.5 keV → 8.814e+19 Hz | iodine gas/aerosol | Volatile; attaches to aerosols & thyroid uptake; environmental monitoring line |
| ¹³⁷Cs | 30.17 y | β⁻ → ¹³⁷ᵐBa → 661.7 keV γ | 661.7 | 661.7 keV → 1.600e+20 Hz | aerosol/particulate | Global fallout tracer; persistent; key 662 keV γ |
| ⁶⁰Co | 5.27 y | β⁻ → 1173.2 & 1332.5 keV γ | 1173.2, 1332.5 | 1173.2 keV → 2.837e+20 Hz; 1332.5 keV → 3.222e+20 Hz | solid/particulate | Powerful γ source; industry & medicine |
| ⁹⁹ᵐTc | 6.01 h | IT → 140.5 keV γ | 140.5 | 140.5 keV → 3.397e+19 Hz | medical (aerosol/liquid) | Medical imaging workhorse; low-energy γ |
| ²¹⁴Pb | 26.8 min | β⁻; 295 & 352 keV γ | 295.2, 351.9 | 295.2 keV → 7.138e+19 Hz; 351.9 keV → 8.509e+19 Hz | aerosol (radon daughter) | Air/indoor radon progeny; strong short-range γ |
| ²¹⁴Bi | 19.9 min | β⁻; 609/1120/1764 keV γ | 609.3, 1120.3, 1764.5 | 609.3 keV → 1.473e+20 Hz; 1120.3 keV → 2.709e+20 Hz; 1764.5 keV → 4.267e+20 Hz | aerosol (radon daughter) | Outdoor/indoor γ backgrounds |
| ²⁰⁸Tl | 3.05 min | β⁻; 2614.5 keV γ | 2614.5 | 2614.5 keV → 6.322e+20 Hz | aerosol (Th chain) | Th-232 chain; high-energy γ benchmark |
| ²³⁹Pu | 24,110 y | α; weak ~51.6 keV γ | 51.6 | 51.6 keV → 1.248e+19 Hz | particulate | Weapons/fuel; detected via α/low-energy γ/X-rays |
| ²³²Th | 1.40×10¹⁰ y | α; γ via daughters (e.g., ²⁰⁸Tl 2614.5 keV) | 2614.5 | 2614.5 keV → 6.322e+20 Hz | mineral dust | Natural series; daughter γ dominates |
| ²³⁸U | 4.47×10⁹ y | α; γ via daughters (²¹⁴Pb/²¹⁴Bi) | 295.2, 351.9, 609.3, 1120.3, 1764.5 | 295.2 keV → 7.138e+19 Hz; 351.9 keV → 8.509e+19 Hz; 609.3 keV → 1.473e+20 Hz; 1120.3 keV → 2.709e+20 Hz; 1764.5 keV → 4.267e+20 Hz | mineral dust | U-series; ambient γ via radon daughters |
Key terms in plain language
Open a term for a concise explanation of language used on this page.
Broadband
A general term for always-on, high-speed Internet access. Broadband can be delivered over fiber, cable, DSL, fixed wireless, cellular, or satellite networks.
Cloud Computing
Computing resources—such as applications, servers, storage, or databases—delivered from remote infrastructure and scaled as requirements change.
Cybersecurity
The practices and controls used to protect identities, devices, networks, applications, and data from unauthorized access, disruption, or manipulation.
Identity and Access Management (IAM)
The systems and policies that determine who a user is, what resources they may access, and how that access is authenticated and reviewed.
API
An application programming interface is a defined way for software systems to exchange data or request functions from one another.
Artificial Intelligence (AI)
Software designed to perform tasks involving prediction, classification, generation, reasoning, or decision support. Business use still requires clear data, governance, security, and human accountability.