Validation tools for fast simulation of electromagnetic showers

R&D task number: G4RD8

Validation tools for fast simulation of electromagnetic showers

Assessment of the accuracy of the fast simulation is vital for the development and employment of those techniques. As fast simulation is used to replace the detailed (so-called full) simulation, the comparison is done against the detailed simulation. It could be applicable both for the traditional shower parametrisation (more on shower parameterization), and the machine learning methods.

Since the most time-consuming part is most commonly the electromagnetic shower simulation, the fast simulation techniques focus on particle showers. Therefore, the validation is performed on the properties of the showers, such as:

  • deposited energy
  • shower profiles (longitudinal = along the initial particle momentum direction; transverse)
  • number of cells with deposits above the threshold
  • cell energy distribution
  • simulation time

Changes relevant for any method of the fast simulation are prototyped in G4 application that can be found on gitlab. It is meant to be split between the source Geant4 code and an extended example. It contains facilities that allow to create several energy deposits: implementation of a sensitive detector, lookup of volumes located at the hit position, as well as fast simulation models that deposit energy on mesh (with either Carthesian or cylindrical coordinates). The basic analysis tools for particle showers are being implemented.

Moreover, this application demonstrates how to connect G4 application with TensorFlow C API (which can be found e.g. in the LCG releases), or with the inference library developed within G4RD7.

Lead and main developers: Anna Zaborowska (