Progress in simulations of micropattern gas avalanche detectors

Helpful for a better understanding of the intrinsic processes in the various gas avalanche detectors are simulations, involving three-dimensional finite element method (FEM) field map computations in order to describe the more and more complex geometries. Drift, multiplication and attachment procedures are simulated using Monte Carlo techniques. Recent results show a remarkable agreement with gain and energy resolution measurements thanks to the refined computations of gas transport properties and improved avalanching models. As examples the influence of wire eccentricity on gas gain and energy resolution in the ATLAS TRT straws is shown as well as performed studies of the Micromegas detector.