Fiber density and uniformity of response of LHCb electromagnetic calorimeter

Discussed is the transverse uniformity of response and the choice of fiber density for the electromagnetic calorimeter of the LHCb experiment at CERN. Response uniformity is optimized by choosing proper tile edge coverage and the density of fibers. Using of side masks is also discussed. “Shashlik” electromagnetic calorimeter is an important part of LHCb calorimeter system, its design, performance requirements and physics tasks are described in detail elsewhere [1]. Present paper addresses the optimization of calorimeter performance in view of light yield and response uniformity. Three types of modules are planned to use in LHCb electromagnetic calorimeter for the inner, middle and outer zones. The modules of all three sections have similar design and identical transversal size of 12.12 × 12.12 cm. The number of calorimeter cells per module and the fiber density are however different. We foresee 9, 4 and 1 cell per calorimeter module and 16, 36 and 64 fibers 1 per cell, to be used for the inner, middle and outer regions respectively. Choice of fiber density for outer region modules is discussed below.