Decay Simulator: Cerium-121

General data

Radioactive decay series

• Cerium-121 1.1 s
• Lanthanum-121 5.3 s · 99.0%
• Barium-121 29.7 s · 99.0%
• Cesium-121 155 s · 99.0%
• Xenon-121 39.1 min · 99.0%
• Iodine-121 2.12 h · 99.0%
• Tellurium-121 19.27 d · 99.0%
• Antimony-121 stable · 99.0%
• Barium-120 24 s · 1.0%
• Cesium-120 60.4 s · 1.0%
• Xenon-120 46.0 min · 1.0%
• Iodine-120 81.7 min · 1.0%
• Tellurium-120 stable · 1.0%

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 - 2, nuclides - 7.

• Tellurium-116 2.49 h · 2.4×10⁻⁷%
• Antimony-116 15.8 min · 2.4×10⁻⁷%
• Tin-116 stable · 2.4×10⁻⁷%
• Iodine-119 18.8 min · 1.0×10⁻⁷%
• Tellurium-119 16.05 h · 1.0×10⁻⁷%
• Antimony-119 38.2 h · 1.0×10⁻⁷%
• Tin-119 stable · 1.0×10⁻⁷%

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.