DV Creating LUND Files

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.

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.

[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 E_i and E_f 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.