# Annihilation of a proton

1. May 8, 2015

### SU403RUNFAST

When a proton is annhilated, is there gamma radiation emitted?

2. May 8, 2015

### Simon Bridge

Why not crunch the numbers and see - what frequency radiation results? Is that part of the EM spectrum corresponding to "gamma radiation"?

3. May 8, 2015

### SU403RUNFAST

I already crunched numbers got .6 picometer wavelength, so i am just checking .....

4. May 8, 2015

### Simon Bridge

OK - so does that correspond to the gamma-ray wavelength?
Did you look it up to see?

5. May 8, 2015

### Orodruin

Staff Emeritus
What do you mean by this? A proton is not going to simply disappear. You need to specify the process you have in mind. Once you have done that, you can start looking at reaction rates and different channels and cross sections.

6. May 8, 2015

### Staff: Mentor

In addition to Orodruin's answer: the process you might have in mind is extremely unlikely.
Annihilation does not always produce photons, and "two photons and nothing else" is a very special case.

7. May 8, 2015

### SU403RUNFAST

I know, you guys are assuming i am trying to solve some problem the situation is that a photon is annhilated in the presence of a stationary electron, forming an electron positron pair along with the original electron. Y+e=e+e+e

8. May 8, 2015

### snorkack

What is the average number of pions produced by proton annihilation? 4,5?
Maximum is 13 (from pion rest mass). Minimum... 1 is obviously impossible (conservation of momentum), but is 2 pions a legal option, and if so then how frequent?

9. May 8, 2015

### Simon Bridge

... that is different from the description in post #1 and the title where you said a proton was being annihilated.

The process: $\gamma + e \rightarrow e+(e+\bar e)$ ... is called "pair production", not "annihilation".
http://web.pdx.edu/~egertonr/ph311-12/pair-p&a.htm

10. May 9, 2015

### Staff: Mentor

5 (experiment, theory). There was some better experimental paper I don't find any more.

@SU403RUNFAST: The additional emission of a photon in the process Simon Bridge described is possible, but the emitted photon there does not have a fixed energy then.

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