[d2n-analysis-talk] BB H2 elastic momentum

[Zein-Eddine Meziani]

You need to take into account the energy loss in the target from your  
0.873GeV to see how close you get to 0.862 GeV. For hydrogen the  
energy loss is roughly 4 MeV/g/cm^2. We also need the energy of the  
beam  and scattering angle to better than three significant digits.

Z.-E.


On Jun 1, 2010, at 11:50 AM, posik at jlab.org wrote:

> Hi Brad,
>
>  In our last meeting after looking at the sh/ps Energy vs the ps  
> energy,
> there were a lot of events that looked like pion type events (low
> preshower energy events). I attached the image from last meeting below
> (pid.png). Just as a refresher, the left is with the proton cuts (as
> defined by the LHRS and T5 coin trigger) and BB vz target and one  
> track
> cuts. The Right has the same cuts as the left and also a 30 chan BB
> cerenkov ADC cut and a BB cerenkov TDC cut.
>
>  Brad has suggested looking at what the reconstructed momentum looks
> like. Here is a plot of the BigBite reconstructed momentum from our
> 1pass H2 run. I attached the plot below. The left plot is with T2
> trigger cut and the right plot is with a coin T5 trigger cut. Both  
> plots
> also have a BB one track cut. The mean for the T5 trigger cut momentum
> falls at ~0.862 GeV, which about what is expected. If I use the  
> elastic
> scattering formula
>
> p' = p/{(1+[2*(p/M)*sin^2(th)]},
>
> where p is the momentum (assume electron mass 0, p = 1.2 Gev)
> p' is the scattered momentum
> M is the proton mass 0.938 GeV
> th is half of the scattering angle (22.5 degrees)
>
> I get p' = 0.873 GeV
>
> - 
> matt<H2_p.png><pid.png>_______________________________________________
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