Progress in the simulation of Multi-strip RPCs

Timing Resistive Plate Chambers in multi-strip configuration, pioneered by the FOPI collaboration [1], are planned for covering the low-granularity part of the CBM-TOF wall. A recent experiment at GSI cave-B has shown that, with an adequate optimization of the strip layout and readout, the multi-strip concept is sound in terms of timing and efficiency, and well suited for a multi-hit environment. The progress since previous discouraging attempts [2] has been made possible through a combined effort of detector design in conjunction with sophisticated simulations [3]. The newly developed RPC-simulation package is by now based on a (1+1+1) factorization of the original 3D problem. Signal formation (across the gas gap) is treated first; signal induction (across the strip) is calculated in a second step by using weighting field techniques. Finally, the propagation along the strip up to the amplifier is calculated by resorting to the HF-solver APLAC [4].