pp2pp simulation is built around GEANT4 simulation package. Running this simulation requires us to migrate away from the familiar root4star interface and begin running simulation in afs. Several example macros have been implemented. The GEANT4 event record is saved in a ROOT file at the end of the simulation run. Beamline geometry is read automatically from TWISS files, which are the output from MAD-X, listing all the elements along the beamline, and stating for each element the s coordinate, the associated optics functions and the kicks. Magnetic fields, ideal dipole and quadrupole magnets with all its imperfections up to the sextupole terms in multipole expansion are simulated in the same way as in MAD-X, so the coefficients of this expansion are also read from TWISS files. Kickers are implemented as a point like change of particle trajectory. RP geometry is fixed according to drawings and measurements. Additionally, there is implemented an auxiliary (hidden) vacuum plane in front of the horizontal RP and in the place of VPD. It can be used as a perfect resolution detector and a beam monitor. Any energy deposit in sillicon strips and scintillator is stored and used for digitization of the detector respond. We have also implemented the simulation of optical photons in scintillators, so it is possible to have the information about time-of-hit. ADC is the energy deposition. Output information includes:
1. Silicon strip clusters in a format of StMuRpsCollection used for muDST production;
2. True level information: scattered protons momenta, collision vertex, time;
3. Additional information: proton positions in front of horizontal RP’s and in the place of VPD's.


First, obtain the simulation by downloading it from this site (pp2pp_v_xx.tar.gz) and unpack it to a location of your choice.
The next step is to set the environmental variables:



Additionaly you may have to use Cern Root from afs:

$source /afs/cern.ch/sw/lcg/app/releases/ROOT/5.34.00/x86_64-slc5-gcc43-opt/root/bin/thisroot.csh

After a configuration, you can start using pp2pp simulation.

A. Running pp2pp simulation interactively
Running the simulation is straightforward. Simply do...

$pp2pp-build/pp2pp

You would get something like this.

Let's generate 3 elastic events. To run a program, use the following command:

/run/beamOn 3

B. Run program pp2pp in batch mode
To run a program in batch mode just simply do:

$pp2pp-build/pp2pp macro.mac

We have implemented several macros, showing how to run pp2pp simulation in various modes.

1. Elastic events - elastic.mac


2. Quasi-elastic mode - qelastic.mac
Generate quasi-elastic events - proton on the one side of the Interaction Point and resonance on the other side.


3. Read events from file:

3.1 singleFile.mac - each line in a file should look like this: p_x p_y p_z V_x V_y V_z


3.2 doubleFile.mac - each line in a file should look like this: p_x1 p_y1 p_z1 p_x2 p_y2 p_z2 V_x V_y V_z


3.3 hepMC.mac - simulate events generated with HepMC.


3.4 starsim.mac - read and simulate events generated with starsim.