Sigma spectrometer for investigation of π--meson dissociation in μ+μ-π- system on nuclei

The on-line ''Sigma'' spectrometer aimed at investigating π- meson dissociation in the μ+μ-π- system during pion interaction with nuclei is constructed at the Institute of High Energy Physics. The spectrometer comprises a beam section, a target with the protective system, a magnetic spectrometer, a muon identifier, a system of control and data acquisition. The beam section of the spectrometer comprises scintillation counters, hodoscopes, proportional chambers and the Cherenkov gas counters. The HP2100 computer has been used for data reception and processing. The procedure of useful events selection has been described. In the experiment 1.15x1011 beam π- mesons have been passed through the spectrometer and 3x106 events have been recorded