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J/psi trigger status

J/psi trigger status. Alla Maevskaya INR RAS 11 March 2009 CBM Collaboration meeting. Outline. Motivation of trigger studies Environment for trigger studies J/ ψ trigger wih MC PID J/ ψ trigger wih real PID J/ ψ efficiency.

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J/psi trigger status

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  1. J/psi trigger status Alla MaevskayaINR RAS 11 March 2009 CBM Collaboration meeting

  2. Outline Motivation of trigger studies Environment for trigger studies J/ψ trigger wih MC PID J/ψ trigger wih real PID J/ψ efficiency Alla Maevskaya INR RAS 11 March 2009

  3. Motivation J/ψ and Ψ’ multiplicity is very low - 1.92 10-5 for J/ψ and 2.24 10-7 Ψ’for CBM energies Measurements will be performed with the highest available interaction rates Fast and efficient event selection based on J/ψ trigger signatureis necessary to reduce the data volume • For 10Mhz iteration rate and storage rate – 25khz • trigger with suppressed factor at least • 400 for mbias events ( or 40 for central) needed. Alla Maevskaya INR RAS 11 March 2009

  4. Simulation environment: • Background: • for target 250mkm • GRID MC production with cbmroot DEC08 • for target 25mkm • 100000 central auau@25GeV events with cbmroot DEC08 • STS & compact RICH & segmented TRD & TOF • L1 fast tracking in STS • L1 tracking in TRD • TRD PID • Signal: • 10000 J/ψ electrons from PLUTO • embedded in 10000 central UrQMD • pure signal: 2 electrons per event Alla Maevskaya INR RAS 11 March 2009

  5. J/ψ trigger efficiency with MC PID • All reconstructed TRD tracks with Pt>1GeV/c was collected • momentum reconstruction of these tracks by STS in fast mode • MC PID • No vertex constraint • J/ψ event candidate: • Events with 2 and more electrons any charge with Pt>1GeV/c • Statistically chosen hadrons according different hadron suppression factor Alla Maevskaya INR RAS 11 March 2009

  6. J/ψ trigger efficiency with real TRD PID • TRD PID by ANN and likelihood • 99% electrons efficiency J/ψ event candidate: • events with 2 tracks identified as electrons with Pt>1GeV/c any sign were selected Ratio of full number of events to events with 2 “J/ψ electron candidates” Alla Maevskaya INR RAS 11 March 2009

  7. J/ψ efficiency after trigger • 10000 j/ψ decayed by Pluto for 2 electrons • this 2 electrons per event • and embedded in 10000 central UrQMD events • were transported throughfull CBM set-up • TRD PID by ANN and likelihood Reconstructed J/ψ in selected events (with 2 tracks identified as electrons with Pt>1GeV/c any sign any origin)‏ Alla Maevskaya INR RAS 11 March 2009

  8. TRD tracks with Pt>1GeV/c in central AuAu 25AGeV UrQMD events p π+ π- K- K+ e μ Number of tracks per event Momentum distribution Particles PDG code Alla Maevskaya INR RAS 11 March 2009

  9. Conclusion • necessary suppression factor is easily reached by selecting events with 2 electrons at Pt > 1 GeV/c any sign any origin • very soft thresholds for electron identification methods keeping 99% of j/psi electrons in TRD is enough to achieve needed for data recording Alla Maevskaya INR RAS 11 March 2009

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