²⁰⁶Ac — Unstable · t½ ≈ 20.0 ms · Decay: β⁺ → ²⁰⁶Ra · Type: synthetic · Uses: research.
²⁰⁷Ac — Unstable · t½ ≈ 50.0 ms · Decay: β⁺ → ²⁰⁷Ra · Type: synthetic · Uses: research.
²⁰⁸Ac — Unstable · t½ ≈ 100 ms · Decay: β⁺ → ²⁰⁸Ra · Type: synthetic · Uses: research.
²⁰⁹Ac — Unstable · t½ ≈ 120 ms · Decay: β⁺ → ²⁰⁹Ra · Type: synthetic · Uses: research.
²¹⁰Ac — Unstable · t½ ≈ 250 ms · Decay: β⁺ → ²¹⁰Ra · Type: synthetic · Uses: research.
²¹¹Ac — Unstable · t½ ≈ 450 ms · Decay: β⁺ → ²¹¹Ra · Type: synthetic · Uses: research.
²¹²Ac — Unstable · t½ ≈ 0.9 s · Decay: β⁺ → ²¹²Ra · Type: synthetic · Uses: research.
²¹³Ac — Unstable · t½ ≈ 1.0 s · Decay: β⁺ → ²¹³Ra · Type: synthetic · Uses: research.
²¹⁴Ac — Unstable · t½ ≈ 8.2 s · Decay: β⁺ → ²¹⁴Ra · Type: synthetic · Uses: research.
²¹⁵Ac — Unstable · t½ ≈ 10.0 s · Decay: β⁺ → ²¹⁵Ra · Type: synthetic · Uses: research.
²¹⁶Ac — Unstable · t½ ≈ 12.0 s · Decay: β⁺ → ²¹⁶Ra · Type: synthetic · Uses: research.
²¹⁷Ac — Unstable · t½ ≈ 69.0 s · Decay: β⁺ → ²¹⁷Ra · Type: synthetic · Uses: research.
²¹⁸Ac — Unstable · t½ ≈ 1.1 min · Decay: β⁺ → ²¹⁸Ra · Type: synthetic · Uses: research.
²¹⁹Ac — Unstable · t½ ≈ 2.0 min · Decay: β⁺ → ²¹⁹Ra · Type: synthetic · Uses: research.
²²⁰Ac — Unstable · t½ ≈ 3.0 min · Decay: β⁺ → ²²⁰Ra · Type: synthetic · Uses: research.
²²¹Ac — Unstable · t½ ≈ 5.0 min · Decay: β⁺ → ²²¹Ra · Type: synthetic · Uses: research.
²²²Ac — Unstable · t½ ≈ 5.0 min · Decay: β⁺ → ²²²Ra · Type: synthetic · Uses: research.
²²³Ac — Unstable · t½ ≈ 2.1 h · Decay: β⁻ → ²²³Th · Type: tracer · Uses: nuclear physics.
²²⁴Ac — Unstable · t½ ≈ 2.9 h · Decay: β⁻ → ²²⁴Th · Type: tracer · Uses: nuclear physics.
²²⁵Ac — Unstable · t½ ≈ 10.0 d · Decay: α → ²²¹Fr · Type: medical isotope · Uses: targeted alpha therapy (cancer treatment).
²²⁶Ac — Unstable · t½ ≈ 29.4 h · Decay: β⁻ → ²²⁶Th · Type: tracer · Uses: nuclear physics.
²²⁷Ac — Unstable · t½ ≈ 21.8 y · Decay: β⁻ → ²²⁷Th · Type: long-lived radionuclide · Uses: radiotherapy precursors, nuclear batteries.
²²⁸Ac — Unstable · t½ ≈ 6.1 h · Decay: β⁻ → ²²⁸Th · Type: natural (Thorium series) · Uses: environmental tracer.
²²⁹Ac — Unstable · t½ ≈ 1.1 h · Decay: β⁻ → ²²⁹Th · Type: synthetic · Uses: research.
²³⁰Ac — Unstable · t½ ≈ 122 s · Decay: β⁻ → ²³⁰Th · Type: synthetic · Uses: research.
²³¹Ac — Unstable · t½ ≈ 7.5 min · Decay: β⁻ → ²³¹Th · Type: synthetic · Uses: research.
²³²Ac — Unstable · t½ ≈ 120 s · Decay: β⁻ → ²³²Th · Type: synthetic · Uses: research.
²³³Ac — Unstable · t½ ≈ 175 s · Decay: β⁻ → ²³³Th · Type: synthetic · Uses: research.
²³⁴Ac — Unstable · t½ ≈ 42.0 s · Decay: β⁻ → ²³⁴Th · Type: synthetic · Uses: research.
²³⁵Ac — Unstable · t½ ≈ 25.0 s · Decay: β⁻ → ²³⁵Th · Type: synthetic · Uses: research.
²³⁶Ac — Unstable · t½ ≈ 3.0 s · Decay: β⁻ → ²³⁶Th · Type: synthetic · Uses: research.
Actinium — isotope count: 31 total · Stable: none · Unstable: 31.
(Data: IAEA LiveChart, NUBASE2020, ENSDF; notable applications: ²²⁵Ac in targeted alpha therapy, ²²⁷Ac in radiotherapy and nuclear batteries, ²²⁸Ac in environmental tracing.)
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.