# What's the minimum energy (thresold) for a proton-electron collision and creation of a neutron?

And Is it the same than for a proton-proton collision and creation of an antiproton?

• Have you tried line-reversing neutron decay? Commented May 15, 2023 at 0:18

Particle interactions are studied within the standard model of particle physics and the Feynman diagrams are the tool to calculate how probable the outcome is.

In your question you are asking whether a proton can by interacting with an electron turn into a neutron.

This interaction is possible, and the probability can be calculated using the method of the diagram above, and energy and momentum conservation has to be applied.

The mass of the neutron is ~Mev/c 939.6, the mass of the proton is ~938.3 Mev/c .

So there is a threshold for the interaction to happen.

same than for a proton-proton collision and creation of an antiproton?

The masses and energies entering in proton proton collisions and the complexity of the interaction to produce antiprotons , with their large mass, while also conserving charge and quantum numbers make the answer "definitely not even similar".

There is no electron-proton energy threshold for this process. You would also need an antineutrino absorption for this process to yield a neutron and the energy of the antineutrino would also enter into the threshold calculation.

• You could emit (and then ignore) a neutrino instead of requiring a three-body collision.
– rob
Commented May 15, 2023 at 2:41
• @rob You are correct, and that is exactly what happens with electron capture where a bound s-state electron collides with a proton inside a nucleus to create a neutron and a neutrino, Commented May 16, 2023 at 1:40