Contribution Oral presentation
The combined liquid xenon - crystal CsI calorimeter of CMD-3 detector
Since 2010 the CMD-3 detector has been collecting data at the e⁺e⁻ collider VEPP-2000 in the Budker Institute of Nuclear Physics. CMD-3 is a general purpose detector designed to study e⁺e⁻ annihilation into hadrons in the wide energy range, E(c.m.s) = 0.3÷2 GeV. During 3 years of operation detector collected integral luminosity of about 60 nb⁻¹. The barrel electromagnetic calorimeter of the detector consists of two subsystems: closest to the beam pipe is the Liquid Xenon calorimeter (LXe) and the outer one is based on CsI scintillation crystals (CsI). LXe calorimeter contains 400 liters of LXe, covers a solid angle 0.8×4π and has a thickness equals to 5.4 X₀. Finely segmented strip structure of the calorimeter electrodes provides the possibility to analyze energy deposition profile through the shower direction, reconstruct tracks of charged particles and measure total energy deposition. The CsI calorimeter consists of 8 octants, located around the LXe calorimeter, and contains 1152 counters. Each counter is based on CsI(Tl) or CsI(Na) crystal of 6×6×15 cm³ size that corresponds to 8.1 X₀ in the direction transverse to the beam. The total thickness of the barrel calorimeter is equal to 13.5 X₀. The main advantage of the combined barrel calorimeter is that the LXe calorimeter allows to measure the coordinates of gamma conversion point with spatial resolution of about 1.5 mm, and additional 8 X₀ of crystal CsI provides the total energy resolution of combined calorimeter of about 4.5% /1GeV. The design of the calorimeter and its current performance are presented. The energy calibration procedures using cosmic rays for LXe and CsI and using elastic e⁺e⁻ scattering process for the LXe calorimeter are presented in this work. The accuracy of calibration constants for LXe and CsI calorimeters are about 2% and 3% correspondingly. Also the gamma energy reconstruction is described in the work and the results of π⁰ reconstruction giving the π⁰ width of about 8% are presented.