[G12] Multiple Photon Efficiency correction

[Lei Guo]

MK is right, and since I did not see any further discussion I guess people at FSU agree too. 

But maybe the other g12 students might benefit also from a bit further discussion: 
if Zulkaida applied multiple photon correction AND the old efficiency map which has a built-in effect of the photon multiplicity, then the current version of  Zulkaida’s results would have been higher by about 5% due to this double counting of the multiplicity effect. We will incorporate these procedures/guidelines in our note and cheatsheet as well.

The new efficiency map which removed the photon multiplicity effect should be applied if you use the following methods:

1. You looped over all photons to get your yield and you don’t need further photon multiplicity correction.
2. You chose one photon where there is more than one, then you correct for it. ( I think this is what Zulkaida did, right?)
(3. You simulated the effect ...)


Lei

Lei Guo
Assistant Professor
Physics Department
Florida International University
Miami, FL

email: leguo at fiu.edu <mailto:leguo at fiu.edu> or lguo at jlab.org
Office:305-348-0234

> On Nov 3, 2015, at 1:50 PM, Michael C. Kunkel <mkunkel at jlab.org> wrote:
> 
> Greetings,
> 
> He had been asking me for the multiple photon corrections. I had assumed it was because he uses multiple photons.
> With that being said, if he is using multiple photons (beam photons), and is using the old efficiency corrections (corrections for tracks with one photon chosen), then his cross sections will be ~5% higher then if he used the correct ones.
> 
> The reason is quite clear from the fact that with multiple photons you have a higher data yield, which deceases the "over efficiency" of the MC simulations.
> 
> BR
> MK
> ----------------------------------------
> Michael C. Kunkel, PhD
> Forschungszentrum Jülich
> Nuclear Physics Institute and Juelich Center for Hadron Physics
> Experimental Hadron Structure (IKP-1)
> www.fz-juelich.de/ikp
> 
> On 11/3/15 8:03 PM, Volker Crede wrote:
>> Dear Michael,
>> 
>> Can you elaborate on why new track efficiency corrections for events with multiple photons should affect Zulkaida's ω cross section? I would like to understand the connection and what has actually "improved" …
>> 
>> - Volker
>> 
>> 
>> On Nov 3, 2015, at 11:01 AM, Michael C. Kunkel <mkunkel at jlab.org> wrote:
>> 
>>> Greetings,
>>> 
>>> I have finished the track efficiency corrections for events with multiple photons. I will present this at the next meeting.
>>> Over all, it seems the new corrections decrease the spectrum by 5%, which was what Lei and I had originally calculated.
>>> 
>>> I would ask Zulkaida to please use these new corrections for his omega Xsection and compare to g11, I think the agreement will be better now.
>>> 
>>> https://jlabsvn.jlab.org/svnroot/clas/users/mkunkel/clas/g12_corrections/All_Corrections/
>>> 
>>> or
>>> 
>>> https://github.com/mckunkel/G12_Corrections
>>> 
>>> use:
>>> 
>>>    double g12_trackEfficiency(double Vz, double P_Ptot_fit, double P_Phi_fit, double P_Theta_fit, double Ep_Ptot_fit,double Ep_Phi_fit, double Ep_Theta_fit, double Em_Ptot_fit, double Em_Phi_fit, double Em_Theta_fit, TString DEG_or_RAD, bool MultPhoton){
>>> 
>>> Set MultPhoton = 1 for multiple photon track efficiency
>>> 
>>> -- 
>>> BR
>>> MK
>>> ----------------------------------------
>>> Michael C. Kunkel, PhD
>>> Forschungszentrum Jülich
>>> Nuclear Physics Institute and Juelich Center for Hadron Physics
>>> Experimental Hadron Structure (IKP-1)
>>> www.fz-juelich.de/ikp
>>> 
>>> _______________________________________________
>>> G12 mailing list
>>> G12 at jlab.org
>>> https://mailman.jlab.org/mailman/listinfo/g12
>> 
>> 
>> 
>> 
>> 
> 
> _______________________________________________
> G12 mailing list
> G12 at jlab.org
> https://mailman.jlab.org/mailman/listinfo/g12

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mailman.jlab.org/pipermail/g12/attachments/20151105/7403f225/attachment.html>