A trigger of events with a high multiplicity of charged particles at the SVD-2 setup

The Thermalization project is currently under way on the extracted proton beam of the U-70accelerator at the Institute for High Energy Physics. The main goal of this experiment is to study the collective behaviorof secondary particles produced in a multiparticle pp interaction at beam energy E = 50–70 GeV. The region of high charged-particlemultiplicities n ch ≥ 10 is investigated. In this region, a significant portion of energy in the center-of-mass system is dissipated on production of secondary particles, which results in formation of a hadronic system. At the initial instant of evolution, the density of this system is high, which may be responsible for the collective behaviorof the secondary particles. The investigations are performed at the SVD-2 wide-aperture magnetic spectrometer. A multichannel trigger scintillation hodoscopeused to select rare eventswith a large number of charged particlesexceeding the predetermined value is described. The main flow of low-multiplicity events is suppressed by the trigger system by a factor of ∼102.