Decay Simulator: Thulium-155

General data

Radioactive decay series

• Thulium-155 21.6 s
• Erbium-155 5.3 min · 99.2%
• Holmium-155 48 min · 99.1%
• Dysprosium-155 9.92 h · 99.1%
• Terbium-155 5.32 d · 99.1%
• Gadolinium-155 stable · 99.1%
• Holmium-151 35.2 s · 0.83%
• Dysprosium-151 18.0 min · 0.67%
• Terbium-151 17.609 h · 0.63%
• Gadolinium-151 124.5 d · 0.63%
• Europium-151 4.6×10¹⁸ a · 0.63%
• Promethium-147 2.62344 a · 0.63%
• Terbium-147 1.64 h · 0.18%
• Gadolinium-147 38.06 h · 0.22%
• Europium-147 24.1 d · 0.22%
• Samarium-147 1.068×10¹¹ a · 0.85%
• Neodymium-143 stable · 0.85%

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 - 1, nuclides - 1.

• Promethium-143 265 d · 4.8×10⁻⁶%

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.