[Clas12_verystrange] Fwd: RE : dvcs plots and simulation

[Lei Guo]

Begin forwarded message:

> From: PROCUREUR Sébastien <sebastien.procureur at cea.fr>
> Date: September 6, 2012 3:56:33 AM EDT
> To: Lei Guo <lguo at jlab.org>
> Subject: RE : dvcs plots and simulation
>
> Hi Lei,
>
> I indeed made some simulations with different values for the torus  
> field, down to 50% of its nominal value.
> DVCS events were generated using dvcsgen, then propagated in Gemc  
> and reconstructed with Socrat. The conclusions are the following  
> (the text below is what I sent to Latifa, Harut, and other people):
> "
> - the electron momentum resolution varies with 1/B as expected,  
> which means the resolution is deteriorated by a factor of 2 with a  
> 50% torus field. The other variables (phi, theta, z) are not  
> affected by the torus field, as expected too.
> - the effect of a 50% torus field is negligible on the "exclusive"  
> resolutions of DVCS (see attached plot, where black corresponds to  
> nominal torus field, and red to 50%). This is because these  
> resolutions are dominated by the proton reconstruction in the  
> Barrel. To understand this, one has to keep in mind that proton  
> resolutions are very close to the CLAS12 requirement (5% in Dp/p)  
> whereas the electron resolution is better (0.5% in Dp/p for a  
> requirement at 1%).
> - a lower torus field increases the electron acceptance. In the  
> simulated regime (Q2>1.5GeV2) this effect is limited to 5%, but is  
> certainly higher at smaller Q2. And also (much) higher for other  
> reactions involving large angle, positively charged particles.
> Of course, these conclusions may differ for other proposals.  
> However, the fact that the electron momentum resolution is better  
> than the original CLAS12 requirements means an optimization between  
> acceptance and "event" resolution should be done.
> "
> Concerning the simulations, what I did for Harut and other people is  
> a reconstruction using the chain Pythia-Gemc-Socrat. Please note  
> that Socrat reconstructs only charged particles, plus photons in the  
> IC calorimeter. Sadly, I should say I prefer not to provide the  
> Socrat code anymore for various reasons, the main one is that the  
> official CLAS12 tracking code (based on Socrat) will soon be  
> released by the software group. However, if you want to study any  
> particular process/configuration (using Pythia generator, or another  
> one compatible with the LUND format), I will do my best to run the  
> whole chain and provide you with the output files from both Gemc and  
> Socrat.
>
> Let me know,
> Sébastien.
>
> ________________________________________
> De : Lei Guo [lguo at jlab.org]
> Date d'envoi : mardi 4 septembre 2012 15:59
> À : PROCUREUR Sébastien
> Objet : dvcs plots and simulation
>
> HI, Dear Sebastien,
>
> Franck gave me your email address. I have two questions for you.
> 1. Franck told me that you did simulation to show the impact of the
> field setting on the p-DVCS experiment. Could you forward those plots
> to me?
> 2. I also heard you did a "full" reconstruction simulation recently.
> Do you have the software available to everybody? If not, could you let
> me know how to replicate what you have done, for other CLAS12
> experiments?
>
>
> Thanks a lot!
>
> Lei
> **************************************
>        @
>       /    *
>      /   ___  ___  Lei Guo _______________________
>     L_O_/ ____ Florida International University____/_/
>         \   |             Physics Dept., CP
> 212                       /  /
>      /    \ |             Miami, FL
> 33199        /                       /  /
>     /  I_/ \  ____ USA _____ /______/__________/  /
>    /   /
> L
>                 /              /              /                       /  /
>   /   /                       /              /              /                       /  /
>  /_/__________/______/______/__________/_/
> /_/__________/______/______/__________/_/
> 305-348-0234(o)
>
> **************************************
**************************************
        @
       /    *
      /   ___  ___  Lei Guo _______________________
     L_O_/ ____ Florida International University____/_/
         \   |             Physics Dept., CP  
212                       /  /
      /    \ |             Miami, FL  
33199        /                       /  /
     /  I_/ \  ____ USA _____ /______/__________/  /
    /   /      
L 
                 /              /              /                       /  /
   /   /                       /              /              /                       /  /
  /_/__________/______/______/__________/_/
/_/__________/______/______/__________/_/
305-348-0234(o)

**************************************






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