Allpix squared simulations of multi-element germanium detectors for synchrotron applications

Abstract

X-rays spectroscopy experiments at synchrotron facilities were limited for many years by the maximum input count rate and the signal-to-background ratio of germanium fluorescence detectors. These limitations are related to the germanium semiconductor device, the sensor configuration and its response to the incident X-ray flux at different energies. In order to understand and quantify such limitations, physics simulation of the detector response is a powerful tool to provide guidelines for designing, prototyping and improving detectors, as well as modelling experimental environments, which reduces time and cost of development. For this purpose, a first complete and operational simulation chain based on Allpix Squared framework is presented, customized to multi-element germanium detectors and combined with three-dimensional simulations of the electric field and the weighting potential, based on COMSOL Multiphysics®. Based on this simulation chain, a quantification of charge sharing effect as well as signal-to-background ratio at different beam energies has been made for a germanium detector equipped with and without collimator. In addition, two experimental measurements have been performed on the SAMBA beamline at SOLEIL synchrotron. The experimental data were used to set up the full simulation chain and good agreements have been observed between data and simulation.