Glass resistive plate chambers for a semi-digital HCAL

The Particle Flow Algorithm (PFA) concept is one of the main features of the future ILC experiments. This implies a highly granular hadronic calorimeter. A 1 cm2 segmentation can be obtained using semi-digital embedded electronics together with an efficient gas detector. The Glass RPC is an excellent candidate that was successfully used in the BELLE experiment. To apply the PFA efficiently it is necessary to reduce the detector dead zones while keeping it as thin as possible. We have designed and constructed very thin GRPCs for which the number and volume of spacers as well as the area of the gas-tight frame are minimized. New resistive coatings were used to reduce cross-talk. Attempts to improve on the high voltage connection were made and novel gas distribution schemes were tested.