Electron-Positron Annihilation, low energy vs high energy mode- do both end in 511 keV Annihilation?

[George Dowell]

Electron-Positron Annihilation, low energy vs high energy mode- do both end in 511 keV Annihilation?

Normal room temperature electron-positron annihilation is a well documented process, used in industrial, medical and metroloogy fields, among others.

 

There are two modes of e-p annihilation, the room temperature or so-called low energy model, and the high energy model (think storage Rings, accelerators, colliders).

 

In the latter category, do the e-p particles annihilate and produce 511 keV opposed photons like in a normal annihilation, or is there a threshold where e=p annihilation can be forced by kinetic energy alone?

 

Citations/ references if you please, not personal opinions, I need to prove this to someone, one way or the other.

 

Thank you for your time.

 

George Dowell

[swansont]

The annihilation releases energy, so there is no threshold - it does not need to be “forced” 

If there is KE, the photons will have more than 511 keV, or (with sufficient energy) you can produce other, heavier particles

 

[George Dowell]

On 8/18/2019 at 2:54 PM, swansont said:

The annihilation releases energy, so there is no threshold - it does not need to be “forced” 

If there is KE, the photons will have more than 511 keV, or (with sufficient energy) you can produce other, heavier particles

 

It's my understanding the electron-positron annihilation can only take place when both particles have no remaining kinetic energy, and my experiments bear that out - always two 180 degree opposed 511 keV photons. When positrons are created they do have kinetic energy, but before annihilation they loose it through collisions or radiative effects.

What I'm trying to figure out and have no direct knowledge of, is the high energy mode (collider- like LEP), when they are forced together with very high kinetic energy naturally that energy is used up, transformed into particles and waves, conserving the original energy. Does this happen, before, during or after annihilation?

Thanks

Geo

 

 

[swansont]

2 hours ago, George Dowell said:

It's my understanding the electron-positron annihilation can only take place when both particles have no remaining kinetic energy, and my experiments bear that out - always two 180 degree opposed 511 keV photons. When positrons are created they do have kinetic energy, but before annihilation they loose it through collisions or radiative effects.

If that were the case, you would not get other results from e- e+ collisions in colliders. But we do.

2 hours ago, George Dowell said:

What I'm trying to figure out and have no direct knowledge of, is the high energy mode (collider- like LEP), when they are forced together with very high kinetic energy naturally that energy is used up, transformed into particles and waves, conserving the original energy. Does this happen, before, during or after annihilation?

Thanks

Geo

During. 

[George Dowell]

11 minutes ago, swansont said:

If that were the case, you would not get other results from e- e+ collisions in colliders. But we do.

During. 

Thanks. Could you point out a reference where these other energies are mentioned please. And if possible, where does the low energy ("thermalized"  or "at rest" they"are calling it) stop and the high energy mode become possible? I'm only concerned with electrons and positrons, not the other positron/particle annihilations.

Thanks for your time.

 

Geo

 

[swansont]

3 minutes ago, George Dowell said:

Thanks. Could you point out a reference where these other energies are mentioned please. And if possible, where does the low energy ("thermalized"  or "at rest" they"are calling it) stop and the high energy mode become possible? I'm only concerned with electrons and positrons, not the other positron/particle annihilations.

Thanks for your time.

 

Geo

 

If by “high energy mode” you mean creating other massive particles, it’s dictated by the mass of the particles you create.

[George Dowell]

3 minutes ago, swansont said:

If by “high energy mode” you mean creating other massive particles, it’s dictated by the mass of the particles you create.

No sir,  sorry I'm not clear, it is only e-e+ is what I'm asking about.

Now I see you said "in colliders" in your answer. That is the high energy mode I'm referring to, but want to know where between Thermalized and a Collider does e-e+. For example at 542 KE, it is not allowed. Before it can, either Bremsstrahlung or collisions happen, either to the positron alone or to a positron-electron atom (positronium), until the pair are at rest, then annihilation happens with the common dual but opposed 511 keV from the pair's rest energy.

Outside of a collider environment, are there commonly known e-p annihilation's that produce, say 1000 keV pairs photons, or anything besides 511 keV pairs?

Thank you.

Geo