O2 vs aliroot pythia6 simulation

O²
1

Hi everybody,

I am doing a validation study for the upgrades in the geometry of the FIT detectors. The latest geometry is in o2 and the previous geometry in Aliroot. I use for Aliroot

$ALIDPG_ROOT/bin/aliroot_dpgsim.sh --mode sim --run 294925 --uid 888333 --generator Pythia6 --nevents 1000 --simulation NoDigitization --detector FOCAL --focalGeometryFile $FOCAL/geometryFiles/geometry.txt

For Aliroot, we use “AtlasTuning”, and I modified the FOCAL geometry configuration include only FV0 and FT0, and the energy is 13 TeV

I am learning to use o2 simulations, so I to start I use

o2-sim -n 10 -g pythia6 -m FT0 FV0

Where I changed in the default energy to 13TeV

The primary to secondary ratios for o2 and Aliroot looks about the same, the same for the eloss of particles in the detectors, timing, etc. However the number of hits that I get in the detectors for o2 is around 1.5 larger that in the Aliroot simulation.

The question is how can I verify that the o2 pythia6 simulation is in “AtlasTuning” as well.

Thanks in advance for your help.

Regards, Edmundo

2

Dear Edmundo,

o2-sim -n 10 -g pythia6 -m FT0 FV0

will likely run Pythia6 default settings.
In principle you should specify the collision energy and the specific tune if you need a special one.
The “AtlasTuning” in your case might correspond to something special to be specified in the Pythia6 configuration, but this is something I am not familiar with.

To add special settings to a Pythia6 run, add this to the command line

--configKeyValues Pythia6.tune=350;Pythia6.win=13500

where tune is the number of preset tunes in Pythia6 (check the manual) and win is the centre-of-mass energy.

Please, refer to this source code for other parameters

if you need to configure more the Pythia6 generator, you should write a pytha6.cfg configuration file with all the details and pass it via

--configKeyValues Pythia6.config=pythia6.cfg