In the calendar today there´s a super nice graph I didn´t make myself, but I have of course made it even prettier than it already was 😉

Todays graph is a so called "cross section graph" for uranium-235.

The cross section sort of tells us about the probability that something will happen to a nucleus; in this case it´s about the cross section/probability that uranium-235 will fission <3

The cross section sort of tells us about the probability that something will happen to a nucleus; in this case it´s about the cross section/probability that uranium-235 will fission <3

On the x-axis is the energy of the neutrons hitting the uranium-235 nucleus, and on the y-axis is the cross-section. As you can see the cross-section is much bigger for low energy neutrons than for high energy neutrons - this means that there is a much much bigger probability for a nucleus to fission when it is hit by a neutron with really low energy.