Contribution Oral presentation
Review of simulations for gas detectors
Gas-based tracking devices are currently undergoing a revival: with the advent of MPGDs (such as Micromegas, GEM, InGrid ...) spatial resolutions of 50μm and better have become commonplace. MGPDs are in addition light, well suited to cover large areas with, and affordable. Traditionally, gas-based detectors are simulated by integrating field gradients and transport tables. This technique is not suitable for MPGDs because the mean free path between collisions, a few μm, is not much smaller than the smallest structural elements nor much smaller than the spatial resolution of the best MPGDs. A more appropriate method consists in tracking electrons from molecule to molecule and applying the various processes (elastic and inelastic collisions, excitation, ionisation, attachment). Magboltz contains an elaborate library of cross section terms - simulations routinely involve well over a hundred terms. Even if the technique is computing time intensive, it has eanwhile been shown to yield accurate results. The method can be used to simulate space charge and charge accumulations on the surfaces of dielectrics. This is even more time intensive, but first results for GEMs show that the main features from the experimental data are reproduced.