Title: 3D Simulation of Electron and Ion Transmission of GEM-based Detectors,
Abstract: Time Projection Chamber (TPC) has been chosen as the main tracking system in
several high-flux and high repetition rate experiments. These include on-going
experiments such as ALICE and future experiments such as PANDA at FAIR and ILC.
Different $\mathrm{R}\&\mathrm{D}$ activities were carried out on the adoption
of Gas Electron Multiplier (GEM) as the gas amplification stage of the
ALICE-TPC upgrade version. The requirement of low ion feedback has been
established through these activities. Low ion feedback minimizes distortions
due to space charge and maintains the necessary values of detector gain and
energy resolution. In the present work, Garfield simulation framework has been
used to study the related physical processes occurring within single, triple
and quadruple GEM detectors. Ion backflow and electron transmission of
quadruple GEMs, made up of foils with different hole pitch under different
electromagnetic field configurations (the projected solutions for the ALICE
TPC) have been studied. Finally a new triple GEM detector configuration with
low ion backflow fraction and good electron transmission properties has been
proposed as a simpler GEM-based alternative suitable for TPCs for future
collider experiments.