Design aspects and prototype test of a very precise TDC system implemented for the Multigap RPC of the ALICE-TOF

The ALICE Time-of-Flight system will be a large area (150 m(2)) detector made by Multigap RPC (MRPC). T he time digitisation is based on the High Performance TDC chip (HPTDC). Tests carried out on board prototypes are discussed, emphasising the optimisation of the effective time resolution of the chip when working in its Very High Resolution Mode. Lab bench tests and test beam results show that a 20 ps resolution has been achieved. (C) 2004 Elsevier B.V. All rights reserved.