Creating stationary neutrons by colliding protons and electrons

[arusse02]

Lets say, in zero gravity space, you have an incredibly precise collider that slams protons and electrons into each other as perfectly as possible such that all momentum is canceled out and the resulting neutron has no velocity relative to the observer. As protons and electrons continue to collide, would you be able to just build up a large clump of stationary neutrons/neutronium or would some phenomenon crop up making this impossible? If this does work, what happens to the growing clump of neutrons? Does it remain stable, or start decaying, and do the new neutrons start interacting with each other via the strong force?

 

[Vanadium 50]

First, you can't do this. The interaction produces a neutrino, which will cause the neutron to recoil. Second, momentum is still conserved, so the neutron will move in the electron direction.

Second, the neutrons will decay with their usual half life.

 

[DaveC426913]

Second, momentum is still conserved, so the neutron will move in the electron direction.

Unless the proton is moving at 1/1836th the speed of the electron.

Second, the neutrons will decay with their usual half life.

~15 minutes.

 

[arusse02]

First, you can't do this. The interaction produces a neutrino, which will cause the neutron to recoil. Second, momentum is still conserved, so the neutron will move in the electron direction.

Second, the neutrons will decay with their usual half life.

In this example both the proton and electron have the same momentum so the electron is traveling at a much higher speed compared to the proton. Presumably the electron in this would be accelerated to a much higher speed so everything is canceled out. Also isn't the neutrino pretty much irrelevant because of how much less energy it has compared to the neutron? Perhaps you could angle the electron and proton very slightly to offset the recoil produced from the neutrino.

The decay period also seems long enough to where you could build up a very large number of neutrons in a small space, and at some point wouldn't the neutrons not decay similar similar to why neutrons in a neutron star don't decay?

 

[PeterDonis]

isn't the neutrino pretty much irrelevant because of how much less energy it has compared to the neutron?

Energy is not the same as momentum. The neutron's recoil is due to the neutrino's momentum.

Perhaps you could angle the electron and proton very slightly to offset the recoil produced from the neutrino.

You can't do this because you can't predict in which direction the neutrino will come out; that's not controllable.

 

[Vanadium 50]

You want to have two accelerators and make a macroscopic amount of matter? Good luck with that. As was once said about Fermilab "I can spit more protons than this machine will ever accelerate."

The decay period also seems long enough to where you could build up a very large number of neutrons in a small space, and at some point wouldn't the neutrons not decay similar similar to why neutrons in a neutron star don't decay?

It's not any more feasible since the first time you proposed this.