Transient Signal Simulation in Pixel Semiconductor Detectors under Pulsed High-Flux Radiation

A new signal propagation module was developed in allpix-squared for transient signal response in semiconductor detectors under pulsed high-flux X-ray or electron radiation. For these high rate sources, since super high density of electrons and holes are deposited in sensor, the interactions between carriers (plasma effects) and the impacts of the carriers' lifetime play important roles in the signal development and have been emphasized in our simulation. The propagation module provides a model to transport carriers in self-consistent field and the external field. A simulation example of XFEL silicon pixel detector reveals the dynamic change of charge cloud in the sensor and some phenomena consistent with the experiments are observed.