Probing into protons with high-energy particles

  • #1
snorkack
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What is easily seen about how the internal structure of proton is explored is collisions of proton with electrons of high and varied energy.
Electrons have an advantage that they are simple particles easy to handle:
  • muons and tauons are short lived
  • neutrinos are hard to aim and detect
  • other protons are complex so results are harder to interpret
But how about photons? Also simple particles.
Do collisions of protons with high energy photons give any information about proton that is complementary to information coming from collisions with high energy electrons, or are collisions with high energy photons useless because they give no information that collisions with electrons do not already give?
 
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  • #2
snorkack said:
the internal structure of proton is explored is collisions of proton with electrons of high and varied energy
and the force carriers are (virtual) photons. It's called Deep Inelastic Scattering

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  • #3
BvU said:
Please. Deep-Inelastic or Deeply Inelastic. If you were in George Sterman's class, he would correct you. I stay on his good side by just saying DIS.

I don't think it is a good use of my time correcting all the wrong "facts" in the original post. These "facts" are no such thing. But I will mention that there have been dozens of neutrino scattering experiments over many decades and the beams can be aimed at detectors hundreds of miles away.

In the words of Dr. Peter Venkman, "Nice shootin', Tex!"
 
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  • #4
Producing a beam of photons with hundreds of MeV is very difficult. The result would be very similar to experiments with electrons.
 
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  • #5
Vanadium 50 said:
Please. Deep-Inelastic or Deeply Inelastic. If you were in George Sterman's class, he would correct you. I stay on his good side by just saying DIS.
I see a lot of folks DO call it deep inelastic scattering. Apparently the Nobel prize committee doesn't care
 
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  • #6
BvU said:
I see a lot of folks DO call it deep inelastic scattering.
George Sterman would say they are wrong, that just because they do it wrong doesn't mean everybody has to, and that in English adverbs modify adjectives.

mfb said:
Producing a beam of photons with hundreds of MeV is very difficult.
Not that hard - even hundreds of GeV are possible. (Well, over a hundred anyway) You can even make beams of tagged photons:

Start with your primary protons. Smash them into your favorite target. About 30% of what comes out will be neutral pions, which almost immediately decay to two photons.

Use magnets to sweep away your charged particles. Now what's left are photons and neutrons, and a few other neutral hadrons. Take this beam and hit a piece of lead with it.

The photons will make electron-positron pairs. Use magnets to capture the electrons (and/or positrons) of either sign of a known momentum p1. Transport these particles downstream.

Now hit another piece of lead with this beam. Some electrons (positrons) will radiate photons, reducing their momentum to p2. When this happens, you know the photon had energy p1-p2.

And now you have a beam of photons where you know the energy oif each individual photon. Problem solved.

Multiple beam lines that do this have been constructed. It's not difficult - there are just a lot of parts.
 
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  • #7
Vanadium 50 said:
George Sterman would say they are wrong, that just because they do it wrong doesn't mean everybody has to, and that in English adverbs modify adjectives.

Not sure how authoritative this journal is, but on page 156.3 in the
1699571776207.png

George Sterman (single author !) said:
1699571504739.png

Perhaps the good man has given up :wink: ?

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  • #8
The hyphen is there. Deep-Inelastic is OK. Deeply Inelastic is OK. Deep (no hyphen) Inelastic makes George Sterman sad.
 
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  • #9
I accept the rebuke from my elders. Wish I wasn't born in a non-english speaking country :smile:

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  • #10
BvU said:
I accept the rebuke from my elders. Wish I wasn't born in a non-english speaking country :smile:

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Or should that be non-English-speaking country?
 
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  • #11
Capital crime ! Aggravated by hyphenomission...

And so on ad infinitum...

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