Medium energy calorimetry at SND: techniques and performances on physics

SND (Spherical Neutral Detector) is a general purpose nonmagnetic detector, successfully operating at Novosibirsk VEPP-2M collider during last four years in the center of mass energy range from 400 MeV up to 1400 MeV. Its crucial part is a 3-layer, fine grained, spherical NaI(Tl) electromagnetic calorimeter consisted of 1632 individual counters. Here we present a detailed description of the calorimeter and its performance, including such topics as calorimeter design, electronics, calibration, energy and spatial resolutions, particle identification. The calorimeter performance is illustrated by examples from the current studies of different physical processes.