DV Creating LUND Files

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The LUND format

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.

[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]

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.


[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.

LUND Header
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)

Writing LUND files

Correct for vertex location