[Clas12_verystrange] My photon definition

[Michael Dugger]

Eugene,

I'll make the beta cut

Thanks!

-Michael

On Thu, 17 May 2018, Eugene Pasyuk wrote:

> Mike,
>
> If you do not apply cut on beta some of what you call "photons" are neutrons.
>
> -Eugene
>
> ----- Original Message -----
>> From: "Michael Dugger" <dugger at jlab.org>
>> To: "clas12 verystrange" <clas12_verystrange at jlab.org>
>> Sent: Thursday, May 17, 2018 9:27:53 AM
>> Subject: [Clas12_verystrange] My photon definition
>
>> Hi,
>>
>> During the meeting yesterday, I was asked for information regarding how I
>> define my photons.
>>
>> Sorry not to get this out yesterday but that was kind of a crazy day for
>> me.
>>
>> Here is how I define my photons:
>>
>> //First I grab values from REC_Particle:
>>
>> for (int j=0;j<nREC;j++){
>>   mPart_t mPartTmp;
>>   int pidTmp   = mcTree.REC_Particle_pid->at(j);
>>   double pxTmp = mcTree.REC_Particle_px->at(j);
>>   double pyTmp = mcTree.REC_Particle_py->at(j);
>>   double pzTmp = mcTree.REC_Particle_pz->at(j);
>>   double pTmp  = sqrt(pow(pxTmp,2)+pow(pyTmp,2)+pow(pzTmp,2));
>>   double eTmp  = 0.0;
>>   int charge   = mcTree.REC_Particle_charge->at(j);
>>
>> //Then I simply take all charge = 0 particles and call those photons
>> //and reset the energy and make a 100 MeV cut:
>>
>> if (charge == 0){
>>     double moVal = mPartTmp.momentum.P();
>>     mPartTmp.momentum.SetE(moVal);
>>     if (moVal > 0.1) mPartPho.push_back(mPartTmp);
>> }
>>
>> //For the case of 2 photons I make an additional cut (for now):
>>
>> int nPho = mPartPho.size();
>>
>> //Define pho2Cut. If pho2Cut = true then these are not used
>>
>> bool pho2Cut = true;
>>
>> //Define the four vector of the 2 photon system and get the
>> //opening angle between them
>>
>> if (nPho == 2) {
>>  TLorentzVector mo2Pho = mPartPho[0].momentum + mPartPho[1].momentum;
>>
>>  TVector3
>> vec1(mPartPho[0].momentum.Px(),mPartPho[0].momentum.Py(),mPartPho[0].momentum.Pz());
>>
>>  TVector3
>> vec2(mPartPho[1].momentum.Px(),mPartPho[1].momentum.Py(),mPartPho[1].momentum.Pz());
>>
>>  double angleVal = vec1.Angle(vec2)*180.0/3.14159;
>>
>> //Then define the line for the cut
>>
>>  double xa1 = 1.0, xa2 = 61.0, ya1 = 0.0, ya2 = 1.0;
>>  double deltaAX = xa2 - xa1;
>>  double deltaAY = ya2 - ya1;
>>  double mValA = deltaAY/deltaAX;
>>  double bValA = ya1 - mValA*xa1;
>>
>> //Make the cut
>>  double yValA = mValA*angleVal + bValA;
>>  if (mo2Pho.Mag() < yValA) pho2Cut = false;
>>
>>
>> Take care,
>> Michael
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