g4-tankresponse

This project is maintained by Matthias Plum <matthias.plum@sdsmt.edu>

About

The g4-tankresponse project provides an I3TankResponse service to be used with topsimulator. This service calculates the response of an IceTop tank or a surface scintillator to incoming particles using Geant4. In order to use this project you need have geant4 installed. The physics in this project is documented in the original internal note.

To use this tank response, one only needs to create the service and pass it to topsimulator. The example in g4-tankresponse/resources/examples/simple_injection.py shows how to do this.

There is also doxygen documentation.

ServiceFactories

I3IceTopResponseFactory<I3G4TankResponse>

The I3G4TankResponse is a specialization of an I3TankResponse. The geometry of the tank, including the snow on top of it, is modelled accurately in Geant4. Incoming particles are tracked by Geant4 including particle interactions in the material. Cherenkov photons emitted in the ice are counted and distributed in time to reproduce the characteristic waveform shape observed in data. They are not tracked through the ice to improve performance.

The number of Cherenkov photons is related to observed photo electrons using a rough calibration with 4GeV muons. More precise calibrations can be obtained by simulating small air showers to obtain a correction factor, which can be set in the “ChargeScale” parameter.

Parameters

RandomServiceName:

Name of a random number generator service.

CherenkovMethod:

Count emitted Cherenkov photons (no Cherenkov photon tracking), defaults to true. If set to false, the number of photo electrons will be determined based on energy deposit inside the tank.

ChargeScale:

A charge correction factor to be used when a more precise calibration is available. Defaults to 1.

TimeConstantZirco:

Time constant for distributing photo electrons in Zirconium lined tanks to accurately model measured waveforms.

TimeConstantTyvek:

Same as TimeConstantZirco, but for the Tyvek tanks.

SafetyMargin:

All particles that get within this margin of a tank will be simulated. Particles outside will be dropped. Tradeoff between speed and precision.

CherenkovWeighting:

EXPERIMENTAL position based weighting of Cherenkov photons inside the tank. Can increase fluctuations (which seem to be too small in our simulations).

VisMacro:

Geant4 visualization macro. You need a visualization enabled Geant4, which is not the case for the normal ports installation.

TriangulatedSnow:

Default value is True

UseScintillator:

EXPERIMENTAL Default value is False