L = 1032 cm-2s-1 at 2 GeV Lpeak = 2*1031 cm-2s-1 at 1 GeV - DC — 1218 hexagonal cells with sensitive wires. σp/p — 1.5-4.5% for 200-1000 MeV/c, σdE/dx/dE/dx = 14%. - SC solenoid magnetic field 1.3 T. - LXe-calorimeter and CsI-calorimeter are in barrel part and BGO-calorimeter is in the end caps. - the vacuum pipe inside DC is made of 0.5 mm aluminum with 17 mm inner radius. - inner shell of the DC is made from CFRP and has 20 mm radius. Search for the decay ω→ηe+e- in η→π+π-π0 decay mode with the CMD-3 detector Budker Institute of Nuclear Physics, Novosibirsk, Russia — V. Mishin, on behalf of CMD-3 collaboration Events selection Abstract A set of selection criteria has been elaborated using Monte-Carlo modeling simulation (MC) to extract the ω→ηe+e- decay events. Using a data sample of 6 pb-1 collected in 3 central points in the energy range close to ω-meson invariant mass the upper limit on the branching ratio of decay has been estimated: B(ω→ηe+e-) < 5 ∙ 10-6, which does not contradict to the Vector Dominance Model (VDM) prediction: (2.0 – 4.8) ∙ 10-6. Preliminary results, further plans Secondary selection criteria To start signal events selection one has to determine charge particles types. Charge particles types are defined using kineamtic property of the decay, by a spatial angle between their tracks. Two tracks are leptonic, if the spatial angle between them less than 1.5 radian. The efficiency of such separating algorithm is 60% approximately. Difference in e/π ionization losses used as additional veto for selected events. Primary selection criteria These criteria have been used to extract the events with appropriate signature having good reconstructed tracks: 1. Transverse momentum is > 40 MeV / c; 2. Total momentum absolute value is < 470 MeV /c; 3. Minimal distance between every track and beam axis is < 1 cm; 4. A number of points on each track is > 10; 5. A track polar angle value is between 0,9 and π - 0,9 radian; 6. 4 charged tracks in event; 7. The total track charge is equal to zero; 8. More than one photon in the signal event. To suppress main background coming from decay ω→π+π-π0 with consequent π0 Daliz decay π0 →e+e- γ one has to investigate ω→ηe+e- kinematic properties. Two missing masses have been chosen to separate the signal events and main background. An event is the signal one in case if parameters matches corresponding regions. Deviation between the signal event parameters and corresponding Gauss curve means have to be less than 3 standard divergences. Additional feature of decays ω→ηe+e- and ω→π+π-π0 has been found in the dependence between π+π- and e+e- total momenta. This feature gives an extra oppotunity to separate signal and main background events, nevertheless, it also suppresses signal events by a half. However, this gives possibility to check, wether selected events are likely being the signal samples or not. Among all used experimental events 3 of them satisfied enumerated selection constraints. Only one of them has 2 photons, however, they are located in the region filled with dense background. Among all used experimental events 3 of them satisfied enumerated selection constraints. Only one of them has 2 photons, however, they are located in the region filled with dense background. Assuming all picked out events are background, the decay relative probability B(ω→ηe+e-) upper limit has been estimated: B(ω→ηe+e-) < 5 ∙ 10-6, which does not contradict corresponding VDM prediction (2.0 – 4.8) ∙ 10-6. Now we are going to modify described selection conditions to take into account Initial State Radiation (ISR). To enhance results objectivity we are going to apply blind-analysis method. To use it one has to choose two independent variables which have sharp prominent peak for the signal and quite flat or monotonous for the background. These variables are presented above. Width of each variable has been measured and blind-box size has been determined (3σ for each variable). All events into area will