Скачать или смотреть Chain reaction: Shooting a single neutron into a chunk of ²³⁵U

This is a variant of the simulation    • Chain reaction: A simple model for nuclear...   modeling one of the most common reactions in nuclear fission, in which a uranium 235 atom, hit by a neutron, decays in a strontium 95 atom, a xenon 139 atom, and two neutrons, having some extra kinetic energy. These two neutrons can hit other uranium atoms, which expel more neutrons, provoking a chain reaction. The difference to the previous simulation is that a single neutron is used at the beginning, instead of several neutrons.
In this simulation, the reaction has been decomposed into three more elementary reactions:
²³⁵U + n → A + B
A → ⁹⁵Sr + ¹³⁹Xe
B → n + n
The first reaction has a certain probability to occur when a neutron remains close to uranium atom for a sufficient time, and when the difference of kinetic energies is not two large. The reactions are exothermic, meaning that the created neutrons tend to have a larger kinetic energy. The masses of the particles have been taken proportional to their atomic weight. However, the reaction probabilities and exothermic energy gain have been tweaked to obtain a nice reaction speed, neither too fast nor too slow.
This video has two parts, showing the same evolution with two different color codings:
Particle type: 0:00
Kinetic energy: 1:24
In the first part, the particles' color depends on their type: neutrons are red, uranium atoms are blue, while strontium and xenon atoms are yellow and green. In the second part, the particles' color depends on their kinetic energy. The graph at the top right shows the number of atoms of each type over time.
To save on computation time, particles are placed into a "hash grid", each cell of which contains between 3 and 10 particles. Then only the influence of other particles in the same or neighboring cells is taken into account for each particle.

Render time: 3 minutes 29 seconds
Compression: crf 23
Color scheme: Turbo, by Anton Mikhailov
https://gist.github.com/mikhailov-wor...

Music: "Start Vacuum" by Karneef‪@karn33f‬

Current version of the C code used to make these animations:
https://github.com/nilsberglund-orlea...
https://www.idpoisson.fr/berglund/sof...
Some outreach articles on mathematics:
https://images.math.cnrs.fr/auteurs/n...
(in French, some with a Spanish translation)

#atoms #particles #fission #nuclearreactions