# Proton/Antiproton interaction

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#### PmbPhy

• Neilep Level Member
• 2794
##### Proton/Antiproton interaction
« on: 02/08/2014 06:42:31 »
In a previous thread the subject came up about the end products of proton/anti-proton interactions. Some of them yield two or more photons at the end of the series. Sometimes the first step in the series is this; (let p proton, ap = antiproton)

$$p + ap -> \pi^{-} + \pi^{+}$$

I wanted to know where I can find the percent of cases where this happens. I asked in the previous thread but never got an answer. I looked in the Handbook of Chemistry and Physics but nothing like that was in there.

Does anybody know the answer or where I can find it and what it's value is. I'm hoping good-ole JP will have the answer. JP?

Note: I don't merely want the answer but I want the source of the answer too or how to calculate it.

#### evan_au

• Neilep Level Member
• 4258
##### Re: Proton/Antiproton interaction
« Reply #1 on: 02/08/2014 07:17:02 »
You could try "Proton-Antiproton Annihilation and Meson Spectroscopy with the Crystal Barrel", which reports on experiments at CERN.

http://arxiv.org/pdf/hep-ex/9708025.pdf

#### PmbPhy

• Neilep Level Member
• 2794
##### Re: Proton/Antiproton interaction
« Reply #2 on: 02/08/2014 07:34:45 »
You could try "Proton-Antiproton Annihilation and Meson Spectroscopy with the Crystal Barrel", which reports on experiments at CERN.

http://arxiv.org/pdf/hep-ex/9708025.pdf
Why? Did you read it? I took a look at it and can't find anything about it. I know that there are tons of papers on this subject but I have neither the timer nor the patience to sift through them all. That's why I started this thread. I.e. I wanted to find someone who already knows where the information is. Thanks for trying though.

#### UltimateTheory

• Sr. Member
• 107
##### Re: Proton/Antiproton interaction
« Reply #3 on: 02/08/2014 14:16:48 »
You should search for "cern proton antiproton branch ratio" (or replace "cern" by specific accelerator name)

for instance this paper
http://cds.cern.ch/record/280676/files/9504362.pdf

mentions such values:
[attachment=19031]
(enlarge image http://www.thenakedscientists.com/forum/index.php?action=dlattach;topic=52059.0;attach=19031;image )

Pion+ Pion- branch has ratio 0.37% +-0.3

while pion+ pion- pion0 pion0 ... (more pions 0) has nearly 36%
« Last Edit: 02/08/2014 14:19:47 by UltimateTheory »
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