Cluster Classification

[HenningSE]

The charge and light yield and thus the number of produced electrons and photons differs for interactions with the same energy deposition but different involved particles and interaction processes. As a result, NEST contains several models to calculate the yields for different particles.

In EPIX we have to specify which NEST model we want to use for each cluster. At the moment the clusters are classified based on the option energy or time.

Energy

• The interaction with the highes energy deposition in a cluster determines the NEST model for the whole cluster.
• This approach was used in GenerateGeant4.py.
• Problem: In most cases electrons (from e.g. ionization processes) contribute in a large fraction to the total energy deposition. Since these individual energy depositions can not be resolved in an experiment, the NEST beta model is meant for electrons from e.g. beta decays so that we will (most likely) get a wrong estimate of the number of photons and electrons.

Time

• The first interaction determines the NEST model for the whole cluster. In this case we assume that all following energy depositions (in this cluster) are somehow causally connected to this first interaction.
• Problem: Interactions from independent processes can also be merged e.g. interactions from a beta decay with subsequent gamma emission. In this case we should use the gamma and beta model of NEST.

As both options have their advantages and drawbacks we need to discuss which option will give us better simulations so it can be used as default case. We could also think about other options like the reconstruction of causal relations of the individual energy depositions.