  The bulk Micromegas detector is considered to be a promising candidate for
building TPCs for several future experiments including the projected linear
collider. The standard bulk with a spacing of 128 micron has already
established itself as a good choice for its performances in terms of gas gain
uniformity, energy and space point resolution, and its capability to
efficiently pave large readout surfaces with minimum dead zone. The present
work involves the comparison of this standard bulk with a relatively less used
bulk Micromegas detector having a larger amplification gap of 192 micron.
Detector gain, energy resolution and electron transparency of these Micromegas
have been measured under different conditions in various argon based gas
mixtures to evaluate their performance. These measured characteristics have
also been compared in detail to numerical simulations using the Garfield
framework that combines packages such as neBEM, Magboltz and Heed. Further, we
have carried out another numerical study to determine the effect of dielectric
spacers on different detector features. A comprehensive comparison of the two
detectors has been presented and analyzed in this work.
