[d2n-analysis-talk] Comments on 1-pass 3He data

[Zein-Eddine Meziani]

I spent the last hour checking few things with Matt and my conclusion  
is that you are correct we are seeing the  quasi-elastic peak off 3He.  
Working directly with the scattered momentum and angle  cleared any  
doubts for me.

I also agree that at 800 MeV  three momentum there is no much elastic  
probability on He3 compared to elastic probability on the proton.

Zein-Eddine
On Mar 4, 2011, at 12:01 PM, Gregg B. Franklin wrote:

> I believe that Matt's 3He missing mass spectra (counts vs W) is
> dominated by quasi-free scattering.  Here's my reasoning (which may be
> wrong but...)
>
> Diana's 1-pass hydrogen data show that the optics is properly  
> calibrated
> and we have a peak in W corresponding to the proton mass and it has a
> width of about 40 MeV FWHM.  Thus I would expect the 3He data to  
> have a
> peak at W=2.808 GeV, the mass of 3He, and a width of roughly 40 MeV
> also.  However, the peak of quasi-free scattering can be estimated by
> assuming the scattering takes place off a single neutron and  
> calculating
> the energy of the outgoing electron.  One then calculates W using a  
> 3He
> mass for the target and you get W=3.028 GeV.  Fermi-momentum will  
> widen
> the peak and  binding effect will shift it slightly.
>
> Matt's W spectrum for 3He has a peak about 3.05 GeV and a FWHM of  
> maybe
> 300 MeV.  To me, this seems consistent with quasi-free scattering.  We
> would like to see a bump at W=2.808 GeV, but I don't see it.
>
> The 3-momentum transfer is about 800 MeV.  This is far above the Fermi
> momentum, so I would not expect the elastic cross section to dominate.
>
>
>
>
>
> -- 
> Prof. Gregg B Franklin
> Head, Department of Physics
> Carnegie Mellon University
> phone: (412) 268-2743   fax: (412) 681-0648
> _______________________________________________
> d2n-analysis-talk mailing list
> d2n-analysis-talk at jlab.org
> https://mailman.jlab.org/mailman/listinfo/d2n-analysis-talk