# Resolution in scattering experiments

1. Jun 21, 2010

### evilcman

Here are two exercises:

1. ) The proton radius is 0.8fm. What energy electron beam do you need for this resolution, if the target is liquid H2?

2.) A pion radius is 0,65fm. What energy pion beam do you need for this resolution by scattering on the electrons of a stationary target(pi-e scattering)? Why is the beam energy so different than in the previous exercise?

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Now, i guess the main point in both cases is that the dr Broglie wavelength of the bombarding particle is the best resolution one can achieve. But, if I just go with de Broglie wavelength = spatial resolution , then I get approx. 1,5GeV and 1,9GeV respectively, which is not that different, so I don't understand the necessity of the last question. Also, I don't think the target material is important. Can someone clarify this?

2. Jun 21, 2010

### Bob S

3. Jun 21, 2010

### evilcman

That just mean that hbar c = 197 MeV fm, I know that, and it does not answer my question.

4. Jun 21, 2010

### Bob S

5. Jun 21, 2010

### evilcman

Yes I know, but since for the pion bombarding I get pc = 1,9 GeV and m=140MeV
=> pc approx E

Now, if I have to transform to the C.M. frame (which is approximately the pion rest frame in this case) that may make a difference, but why should I do that?

6. Jun 21, 2010

### Bob S

The real physics is usually in the CM reference frame.

Bob S