Numerical modelling of gaseous ionization detectors

The working of gaseous ionization detectors can be broadly broken into few major steps: generation of primaries, their transport and amplification due to applied electromagnetic field, and, finally, induction of signal on pick-up electrodes due to movement of electrons and ions. Proper design and optimum utilization of such detectors require thorough understanding of each of these steps. Since they possess significant complexity, numerical modelling turns out to be an important tool to explore the dynamics and response of these detectors. There are several possible approaches that may be adopted to carry out detailed and realistic numerical simulation of gaseous detectors. Among these, the Monte-Carlo particle approach adopted by the Garfield++ toolkit is among the most prominent possibilities. Recently, a deterministic hydrodynamic approach has also turned out to be useful for this purpose. The steps necessary to create mathematical and numerical models of a gaseous detector is presented here, utilizing both particle and hydrodynamic approaches. Simple examples are used to illustrate the advantages and disadvantages of both the approaches.