Cold Electronics For The Liquid Argon Hadronic End-Cap Calorimeter Of Atlas

For the ATLAS hadronic end-cap calorimeter a monolithic Gallium Arsenide front-end chip has been developed. Detailed investigations of many chips have been carried out both at room and at cryogenic temperatures. The dynamic behavior as well as the noise characteristics are presented. The full production (6600 chips) has been completed and quality control tests are going on. 15 preamplifier and summing boards have been produced and tested according to the ATLAS quality assurance procedure. The characteristics of coaxial cables used for analog signals transmission have been studied. The model of the signal distortion is derived and applied to predict the signal shape.