Speaker
Description
Simulations of the detection process are an essential step in the
assessment of a proposed detector design. Often, complex Monte-Carlo
simulators with a wide range of applications are employed for this
task, as they provide the most realistic and adaptable computational
models for the interactions between particles and the detector. For
instance, the Bergen pCT collaboration develops a digital tracking
calorimeter for proton computed tomography (pCT) using the program GATE
based on Geant4.
In the context of gradient-based optimization and differentiable
programming, the size, complexity and heterogeneity of such codes makes
it difficult to integrate common algorithmic differentiation (AD) tools
based on operator overloading. As an example, parts of Geant4 v11.0.0
reinterpret G4double's as integers or cast them to (C++) double's, and
do therefore not compile when G4double is redefined as an AD type. We
believe that such issues are not fundamental and can be overcome with
enough work. Yet, they provide a strong motivation to build AD tools
that, from the perspective of a user, need less integration efforts.
In this talk, we present such an alternative approach, and the current
state of developing it further to support GATE/Geant4.
