AUTHOR=Asai Makoto , Cortés-Giraldo Miguel A. , Giménez-Alventosa Vicent , Giménez Gómez Vicent , Salvat Francesc 

TITLE=The PENELOPE Physics Models and Transport Mechanics. Implementation into Geant4

JOURNAL=Frontiers in Physics

VOLUME=Volume 9 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/physics/articles/10.3389/fphy.2021.738735

DOI=10.3389/fphy.2021.738735

ISSN=2296-424X

ABSTRACT=A translation of the {\sc penelope} physics subroutines to C++, designed
as an extension of the Geant4 toolkit, is presented. The Fortran code
system {\sc penelope} performs Monte Carlo simulation of coupled
electron-photon transport in arbitrary materials for a wide energy
range, nominally from 50 eV up to 1 GeV. {\sc penelope} implements the
most reliable interaction models that are currently available, limited
only by the required generality of the code. In addition, the transport
of electrons and positrons is simulated by means of an elaborate class
II scheme in which hard interactions (involving deflection angles or
energy transfers larger than pre-defined cutoffs) are simulated from the
associated restricted differential cross sections. After a brief
description of the interaction models adopted for photons and
electrons/positrons, we describe the details of the class-II algorithm
used for tracking electrons and positrons. The C++ classes are
adapted to the specific code structure of {\sc Geant4}. They provide a
complete description of the interactions and transport mechanics of
electrons/positrons and photons in arbitrary materials, which can be
activated from the {\tt G4ProcessManager} to produce simulation results
equivalent to those from the original {\sc penelope} programs. The
combined code, named {\sc PenG4}, benefits from the multi-threading
capabilities and advanced geometry and statistical tools of {\sc
Geant4}.