Electron-Proton Collision: Annihilation and Mass Conversion Explained

[Icebreaker]

If an electron collides with a proton? I am told they annihilate, but can something as massive (relatively) as a proton could be destroyed by an electron? That is, will the entire mass of the proton be converted to energy?

 

[chroot]

1) They don't annihilate.

2) Protons and electrons cannot be destroyed. Protons can be broken up into quark-gluon plasma, but electrons are fundamental and have no internal parts.

3) Collisions like this typically result in kinetic energy being traded for rest-mass - a lot of new heavy particles are created, which carry away the energy. The particles typically rapidly decay into gamma radiation.

- Warren

 

[SpaceTiger]

2) Protons and electrons cannot be destroyed. Protons can be broken up into quark-gluon plasma, but electrons are fundamental and have no internal parts.

Whoa, hold up, how are we defining "destroyed"? Electrons can annihilate with positrons (as can protons with anti-protons).

 

[chroot]

SpaceTiger,

Of course, good point.

- Warren

 

[Davorak]

What do you mean collide? Scatter?

Electrons can be absorbed into the nucleus of atom called electron capture or K capture. This will turn one proton into a neutron with emissions of an electron neutrino.

It is called K capture because the lowest electron shell in a many electron atom is called the k shell. This will also result in X-rays when that lower orbital is filled again.

This process is greatly suppressed with just one proton and electron. Though it is still possible just unlikely.

 

[Icebreaker]

What if both the proton and the electron have very little kinetic energy?

 

[Davorak]

With low kinetic energy the electron will just fall into the ground state of the hydrogen atom.

K capture is just an unlikely quantum event for the one proton and electron. The electron and proton are my energetically favored over the single neutron and electron neutrino.