Decay Simulator: Americium-241

General data

Radioactive decay series

• Americium-241 432.6 a
• Neptunium-237 2.144×10⁶ a
• Protactinium-233 26.975 d
• Uranium-233 1.5919×10⁵ a
• Thorium-229 7908 a
• Radium-225 14.8 d
• Actinium-225 9.9190 d
• Francium-221 4.801 min
• Astatine-217 32.6 ms
• Bismuth-213 45.61 min
• Thallium-209 2.162 min · 2.1%
• Radon-217 0.59 ms · 0.012%
• Polonium-213 3.706 μs · 97.9%
• Lead-209 3.235 h
• Bismuth-209 2.01×10¹⁹ a
• Thallium-205 stable

Rare branches (below 0.01%)

Rare branches are transformations that occur in fewer than 0.01% of decays, e.g. double beta decay or cluster emission. The nuclides they produce are practically absent from a sample, so they are hidden by default to keep the main path clear. In this series: branches - 3, nuclides - 5.

• Radium-221 16 s · 0.005%
• Bismuth-211 2.14 min · 5.3×10⁻¹⁰%
• Thallium-207 4.77 min · 6.2×10⁻¹⁰%
• Polonium-211 0.516 s · 1.5×10⁻¹²%
• Lead-207 stable · 6.2×10⁻¹⁰%

How to read the simulation

Grid: each pixel is one atom of the starting isotope. When an atom decays, the pixel takes the colour of the decay product - in decay series mode the product can decay further. The moment each atom decays is random, but the probability follows from the half-life, so after one T½ about half of the atoms remain, after two - about a quarter.

Chart N(t): what percentage of the sample atoms each nuclide makes up at a given moment. The line of the starting isotope falls (by half after each T½), the lines of stable products rise, and those of short-lived ones first rise, then fall.

Chart A(t): activity, i.e. the number of decays per second (becquerel, Bq). It depends on the number of atoms and on how fast they decay: for the same number of atoms, the shorter the T½, the higher the activity.

Simulation time runs faster (or slower) than real time - the time scale slider sets the multiplier. This way you can watch the decay of isotopes that live from fractions of a second to billions of years.

Well-known isotopes

• H-3 - Tritium - glowing watch hands, nuclear fusion fuel.
• C-14 - Radiocarbon dating.
• K-40 - Natural radioactivity - in bananas and in our bodies.
• Co-60 - Radiotherapy and radiation sterilization.
• I-131 - Thyroid treatment; Chernobyl fallout.
• Cs-137 - Long-lasting contamination after Chernobyl and Fukushima.
• Rn-222 - Radon in basements and mines.
• Ra-226 - The longest-lived isotope of radium - the element discovered by Marie and Pierre Curie in 1898.
• U-235 - Nuclear power plant fuel; start of the actinium series.
• U-238 - Age of the Earth; start of the uranium series.
• Pu-238 - Power source for space probes (Voyager, Curiosity rover).
• Am-241 - Ionization smoke detectors.