Understanding the Strong Force: Protons and Neutrons in Collision

[ranrod]

I apologize for the very simple question, but I find often the simplest questions are the ones not answered in books.

If a free-floating proton collides with a free-floating neutron, do they get bound together by the strong nuclear force? Let's say it's a low-energy collision - both particles are gently meandering the cosmos when they meet. Does the strong force bind them together as soon as they touch forming deuterium? I was wondering if all simple particles like neutrons and proton carry the strong force within them. If the 2 particles meeting does not create a bond, how do they normally bond?

 

[JDługosz]

Yes, all protons and neutrons have a strong "charge" in the same way that electrons have an electric charge. The strong force is very short range, so you have to bring them very close together so they nearly touch before they stick.

A p and an n are easy, and can indeed drift together like that. Two p's won't since the electric force acts at a long distance and will push them apart. It's like two opposite magnets that are very strong but covered with velcro: you have to get them together and only then will they stick.

Just don't ask why two p's or two n's don't stick together (I did, and got referred to textbooks but no simple answer). The strong force is more complicated than the electric force.

--John