Difference between revisions of "DV Creating LUND Files"

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The LUND file format is broken into two parts. The first part of the format is the header, which basically tells how many particles follow this line.  For Moller scattering, this number should always be two electrons.  The second component of the LUND format contains the kinematic variable for the scattered electron and the Moller electron.
 
The LUND file format is broken into two parts. The first part of the format is the header, which basically tells how many particles follow this line.  For Moller scattering, this number should always be two electrons.  The second component of the LUND format contains the kinematic variable for the scattered electron and the Moller electron.
  
The LUND format has extra variables that are not utilized within GEMC.  Only the '''BOLD''' variables are necessary within GEMC simulations.
+
The LUND format has extra variables that are not utilized within GEMC.  Only the '''BOLD''' variables are necessary within GEMC simulations.[1]
  
 +
NOTE: Newer versions of GEMC use different format header.  GEMC 2.4 and 2.6 are run for the same 10 events under the same circumstances with identical gcard files.  The ouput is displayed in text format instead of evio.
 +
 +
 +
GEMC 2.4
 +
[[File:HeaderGEMC2_4.png]]
 +
 +
 +
 +
LUND File info for header
 +
[[File:HeaderLUND.png]]
 +
 +
 +
 +
GEMC 2.6
 +
[[File:HeaderGEMC2_6.png]]
 +
 +
 +
GEMC 2.4 had been taking the 5th element on the first line of each LUND event, the beam polization for the 5th entry in the header array (10,5).  Newer GEMC is grabbing the 6th element of the first line of each LUND event.
 +
 +
This can be fixed by adding an additional column with value 1 every 3rd row to the LUND file.
 +
 +
<pre>
 +
sed -i -e '1i\ \' LH2_0Sol_0Tor_11GeV_IsotropicPhi_ShieldOut*/LH2_0Sol_0Tor_11GeV_IsotropicPhi_ShieldOut_*.LUND
 +
</pre>
 +
 +
[[File:HeaderGEMC2_6fix.png]]
 
==The Header==
 
==The Header==
 
{| border=1 align=center
 
{| border=1 align=center
Line 59: Line 85:
  
 
===6:x===
 
===6:x===
This represents the Bjorken x scaling variable.   
+
This represents the Bjorken x scaling variable.  [2]
  
 
<math>x=\frac{-q^2}{2p\cdot q}=\frac{-q^2}{2M\nu}=\frac{Q^2}{2M\nu}</math>
 
<math>x=\frac{-q^2}{2p\cdot q}=\frac{-q^2}{2M\nu}=\frac{Q^2}{2M\nu}</math>
Line 67: Line 93:
  
 
===7:y===
 
===7:y===
<math>y=\frac{p\cdot q}{p\cdot k}=\frac{\nu}{E_i}=\frac{E_i-E_f}{E_i}</math>
+
<math>y=\frac{p\cdot q}{p\cdot k}=\frac{\nu}{E_i}=\frac{E_i-E_f}{E_i}</math>[2]
  
 
===8:W===
 
===8:W===
Line 77: Line 103:
  
 
===9:<math>Q^2</math>===
 
===9:<math>Q^2</math>===
This represents the squared 4-momentum-transfer vector q of the exchanged virtual photon.
+
This represents the squared 4-momentum-transfer vector q of the exchanged virtual photon.[3]
  
  
Line 164: Line 190:
  
 
===4:Particle ID===
 
===4:Particle ID===
This quantity follows the Particle Data Group Monte Carlo numbering scheme for representing what type of particle is simulated.
+
This quantity follows the Particle Data Group Monte Carlo numbering scheme for representing what type of particle is simulated.[4]
  
 
[[File:MontecarlorPDGparticleID.pdf]]
 
[[File:MontecarlorPDGparticleID.pdf]]
Line 204: Line 230:
 
This represents the z position within the eg12 detector at time t=0.
 
This represents the z position within the eg12 detector at time t=0.
  
=Writing LUND files=
 
Reading the GEANT4 simulation output in,
 
<pre>
 
void MollerLUND()
 
{
 
        struct evt_t
 
                {
 
                Long_t event;
 
                Float_t IntKE, IntMom[3],IntPos[3],FnlKE,FnlMom[3],FnlPos[3],MolKE,MolMom[3],MolPos[3];
 
                };
 
        ifstream in;
 
        in.open("MollerScattering_NH3_4e8incident.dat");
 
        evt_t evt;
 
        Int_t nlines=0;
 
        TFile *f = new TFile("MollerScattering_NH3_4e8incident.root","RECREATE");
 
        TTree *tree0 = new TTree("MollerScattering_NH3_4e8","Moller data from ascii file");
 
        FILE *f0;
 
        f0=fopen("MollerScattering_NH3_4e8.LUND","w");
 
               
 
        tree0->Branch("evt",&evt.event,"event/I:IntKE/F:IntPx:IntPy:IntPz:IntPosx:IntPosy:IntPosz:FnlKE:FnlPx:FnlPy:FnlPz:FnlPosx:FnlPosy:FnlPosz:
 
                MolKE:MolPx:MolPy:MolPz:MolPosx:MolPosy:MolPosz");
 
               
 
        while(in.good())
 
                {
 
                evt.event=nlines;
 
                in >> evt.IntKE >> evt.IntMom[0] >> evt.IntMom[1] >> evt.IntMom[2]  >> evt.IntPos[0]
 
                >> evt.IntPos[1] >> evt.IntPos[2] >> evt.FnlKE >> evt.FnlMom[0] >> evt.FnlMom[1] >> evt.FnlMom[2]
 
                >> evt.FnlPos[0] >> evt.FnlPos[1] >> evt.FnlPos[2] >> evt.MolKE >> evt.MolMom[0] >> evt.MolMom[1]
 
                >> evt.MolMom[2] >> evt.MolPos[0] >> evt.MolPos[1] >> evt.MolPos[2];                double Nu;
 
                double x_bj; // Bjorken-x
 
                double y;
 
                double W ; // missing mass
 
       
 
// Momentum and Energy are measured in MeV!
 
       
 
                evt.FnlKE=sqrt(evt.FnlMom[0]*evt.FnlMom[0]+evt.FnlMom[1]*evt.FnlMom[1]+evt.FnlMom[2]*evt.FnlMom[2]+0.511*0.511);
 
                evt.MolKE=sqrt(evt.MolMom[0]*evt.MolMom[0]+evt.MolMom[1]*evt.MolMom[1]+evt.MolMom[2]*evt.MolMom[2]+0.511*0.511);
 
       
 
       
 
                Nu=evt.IntKE-evt.FnlKE;
 
                Qsqrd=4*evt.IntKE*evt.FnlKE*(1-evt.FnlMom[2]/evt.FnlKE)/2; /* should be final momentum and not final energy*/
 
               
 
                x_bj=Qsqrd/(2*0.938*Nu);
 
                y=Nu/evt.IntKE;
 
                W=0.938*0.938+2*0.938*Nu-Qsqrd;
 
                if(W>0)
 
                        W=sqrt(W);
 
               
 
//
 
// MeV MUST be converted to GeV for LUND format! 
 
 
                double px,py,pz;
 
                double Px,Py,Pz;
 
                double KE,ke;
 
               
 
                Px=evt.FnlMom[0]/10;
 
                Py=evt.FnlMom[1]/10;
 
                Pz=evt.FnlMom[2]/10;               
 
                px=evt.MolMom[0]/100;
 
                py=evt.MolMom[1]/100;
 
                pz=evt.MolMom[2]/100;
 
               
 
                KE=evt.FnlKE/10;
 
                ke=evt.MolKE/100;
 
 
 
                fprintf(f0,"%d\t%g\t%g\t%g\t%g\t%g\t%g\t%g\t%g\t%g\n",2,1.,1.,1.,1.,x_bj,y,W,Qsqrd,Nu);
 
                fprintf(f0, "%d\t%g\t%g\t%g\t%g\t%g\t%f\t%f\t%f\t%f\t%g\t%g\t%g\t%g\n",
 
                        1,-1.,1.,11.,0.,0.,Px,Py,Pz,KE,0.000511, 0.,0.,0.);
 
                fprintf(f0, "%d\t%g\t%g\t%g\t%g\t%g\t%f\t%f\t%f\t%f\t%g\t%g\t%g\t%g\n",
 
                        2,-1.,1.,11.,0.,0.,px,py,pz,ke,0.000511, 0.,0.,0.);
 
               
 
                       
 
                nlines++;
 
                tree0->Fill();
 
                }
 
        printf("NumberLines=%d\n",nlines);
 
        tree0->Print();
 
        tree0->Write();
 
        delete tree0;
 
               
 
}
 
</pre>
 
 
 
The file is written as seen below.
 
 
[[File:LUND_view.png]]
 
 
=Corrections=
 
The prefered coordinates for the reconstruction within GEMC would have the vertex location at (0, 0, 0).  The Moller event data from GEANT4 contains the location within that simulation where the scattering occured.  These variables will need to be renormalized within the LUND file to zero. Only the 14th column within the 2nd and 3rd rows out of every 3 rows needs to be changed.  Using a script:
 
 
 
<pre>awk '{if('NR%3==2'||'NR%3==0') {$14="0"}; print $0}' MollerScattering_NH3_4e8.LUND>MollerScattering.LUND</pre>
 
  
The LUND format has a limit of 75000 lines, so to account for this
+
----
  
<pre>split -l 75000 MollerScattering.LUND MollerScattering_NH3_4e9 </pre>
+
=Links=
  
=References=
+
[[DV_RunGroupC_Moller#Creating_LUND_Files|Back]]

Latest revision as of 18:47, 8 September 2017

The LUND format

The LUND file format is broken into two parts. The first part of the format is the header, which basically tells how many particles follow this line. For Moller scattering, this number should always be two electrons. The second component of the LUND format contains the kinematic variable for the scattered electron and the Moller electron.

The LUND format has extra variables that are not utilized within GEMC. Only the BOLD variables are necessary within GEMC simulations.[1]

NOTE: Newer versions of GEMC use different format header. GEMC 2.4 and 2.6 are run for the same 10 events under the same circumstances with identical gcard files. The ouput is displayed in text format instead of evio.


GEMC 2.4 HeaderGEMC2 4.png


LUND File info for header HeaderLUND.png


GEMC 2.6 HeaderGEMC2 6.png


GEMC 2.4 had been taking the 5th element on the first line of each LUND event, the beam polization for the 5th entry in the header array (10,5). Newer GEMC is grabbing the 6th element of the first line of each LUND event.

This can be fixed by adding an additional column with value 1 every 3rd row to the LUND file.

sed -i -e '1i\ \' LH2_0Sol_0Tor_11GeV_IsotropicPhi_ShieldOut*/LH2_0Sol_0Tor_11GeV_IsotropicPhi_ShieldOut_*.LUND

HeaderGEMC2 6fix.png

The Header

LUND Header
Column Quantity
1
Number of Particles
2
Number of Target Nucleons
3
Number of Target Protons
4
Target Polarization
5
Beam Polarization
6
x
7
y
8
W
9
[math]Q^2[/math]
10
[math]\nu[/math]

Where

1:Number of Particles

This line tells how many particles follow the header line. For Moller Scattering, this number should always be 2.

2:Number of Target Nucleons

For this simulation, only an electron-electron collision is considered. This quantity is always set to 1 for the one stationary electron we consider the incident electron scattering from.

3:Number of Target Protons

For Moller Scattering, there are no target protons. This number is set to 1, but does not have any effect within the GEMC simulations.

4:Target Polarization

This represents the polarization of the target material, either positive or negative 1. This value is always set to 1 and has no effect within the GEMC simulations.

5:Beam Polarization

This represents the polarization of the electron beam, either negative or positive 1. This value is always set to positive 1.

6:x

This represents the Bjorken x scaling variable. [2]

[math]x=\frac{-q^2}{2p\cdot q}=\frac{-q^2}{2M\nu}=\frac{Q^2}{2M\nu}[/math]


Where M is the rest mass-energy of the proton[math] M\approx 938MeV[/math]

7:y

[math]y=\frac{p\cdot q}{p\cdot k}=\frac{\nu}{E_i}=\frac{E_i-E_f}{E_i}[/math][2]

8:W

The invariant mass of the final hadronic system


[math]W^2\equiv (p+q)^2=M^2+2M\nu+q^2=M^2+2M\nu-Q^2[/math]

9:[math]Q^2[/math]

This represents the squared 4-momentum-transfer vector q of the exchanged virtual photon.[3]


[math]Q^2\equiv -q^2[/math]


Where q is the momentum transfer betwwn the incident electron and target via the virtual photon.


[math]q\equiv k_i-k_f[/math]

10:[math]\nu[/math]

This represents the energy loss between scattering electrons.

[math]\nu = \frac{p\cdot q}{M}[/math]

This can be written in the Lab frame as:


[math]\nu\equiv E_i-E_f[/math]


where Ei and Ef are the initial and final electron energies.

Particles

Particle Data
Column Quantity
1
Index
2
Charge
3
Type (1 is active)
4
Particle ID
5
Parent Index
6
Daughter Index
7
Momentum x (GeV)
8
Momentum y (GeV)
9
Momentum z (GeV)
10
[math]E[/math]
11
Mass
12
Vertex x (cm)
13
Vertex y (cm)
14
Vertex z (cm)


Where

1:Index

From the header line 1, which states how many particles follow, this counts in increments of one up to the required number.

2:Charge

-1, 0, 1

3:Type

1 denotes that this is an active particle that can interact within the simulation.

4:Particle ID

This quantity follows the Particle Data Group Monte Carlo numbering scheme for representing what type of particle is simulated.[4]

File:MontecarlorPDGparticleID.pdf

5:Parent Index

This signifies if the particle can be considered a primary (=0) or secondary particle. For this simulation, GEMC does not utilize this variable and all values have been set to 0

6:Daughter Index

This signifies if the particle has created secondary particles. For this simulation, GEMC does not utilize this variable and all values have been set to 0.

7:Momentum x

This is the value of the momentum vector in the x direction. Values must be given in GeV.

8:Momentum y

This is the value of the momentum vector in the y direction. Values must be given in GeV.

9:Momentum z

This is the value of the momentum vector in the z direction. Values must be given in GeV.

10:E

E is the total relativistic energy,

[math]E\equiv \sqrt{p^2+m^2}[/math]

For the Ultrarelativistic limit,

[math]E\approx p\ \ \ [/math]Since [math]p\ggg m[/math]

11:Mass

This represents the rest mass-energy of the particle being simulated. For Moller scattering this value has been set to .000511 GeV.

12:Vertex x

This represents the x position within the eg12 detector at time t=0.

13:Vertex y

This represents the y position within the eg12 detector at time t=0.

14:Vertex z

This represents the z position within the eg12 detector at time t=0.



Links

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