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Electronics for Calorimeters at LHC Veljko Radeka Brookhaven National Laboratory, Upton, NY 11973-5000 [email protected] Abstract Major design differences in the readout design arise in Some principal design features of front-end electronics different experiments from trying to balance the answers for calorimeters in experiments at the LHC will be to two questions: a) how much electronics and what highlighted. Some concerns arising in the transition from electronic functions need to be on the calorimeter; and b) the research and development and design phase to the how to minimize the number of interconnections and construction will be discussed. Future challenges will be transmission lines (copper or fiber) for transfer of indicated. information from the calorimeter. Each experiment uses a unique approach, in which I. INTRODUCTION preference of the designers has played a decisive role. One of the design considerations was how near to the signal Calorimetry in large detectors at the LHC poses some input to digitize and, consequently, whether to have an requirements on readout electronics that are quite different analog or digital pipeline. The readout systems were than for any other detector subsystem. The main distinction described in some detail in the Proceedings of the 6 th is, a) in the large dynamic range of energies to be measured; Workshop on Electronics for LHC Experiments, 2000. The and b) uniformity of response and accuracy of calibration two large hadron collider experiments, CMS and ATLAS, over the whole detector. As in all other functions of the each have several different types of EM and hadron detector, low noise of front-end amplifiers is essential. calorimeters for the barrel, end-cap, and forward regions. Unique, too, is the requirement for very low coherent noise, I will comment here only on some common or unique as the energy measurement involves summation of signals