J/psi trigger status Alla Maevskaya INR RAS 11 March 2009 CBM Collaboration meeting

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

Motivation J/ψ and Ψ’ multiplicity is very low for J/ψ and Ψ’for CBM energies Ψ’ for CBM energies Measurements will be performed with the highest available interaction rates available interaction rates Fast and efficient event selection based on J/ψ trigger signatureis necessary to reduce the data volume signature is 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

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

J/ψ trigger efficiency with MC PID All reconstructed TRD tracks with Pt>1GeV/c was collected All reconstructed TRD tracks with Pt>1GeV/c was collected momentum reconstruction of these tracks by STS in fast mode momentum reconstruction of these tracks by STS in fast mode MC PID MC PID No vertex constraint No vertex constraint J/ψ event candidate: J/ψ event candidate: Events with 2 and more electrons any charge with Pt>1GeV/c Statistically chosen hadrons according different hadron suppression factor Hadron rejection factor Full/selected target 250mkm Full/selected target 25mkm Alla Maevskaya INR RAS 11 March 2009

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” MC PID Like>0.4Ann>0.5 Target 250μ Target 25μ Alla Maevskaya INR RAS 11 March 2009

J/ψ efficiency after trigger j/ ψ decayed by Pluto for 2 electrons this 2 electrons per event and embedded in 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) ‏ MC PID LikeAnn S + B 15%16%19% Pure signal Alla Maevskaya INR RAS 11 March 2009

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

Conclusion necessary suppression factor is easily reached by selecting events with 2 electrons at Pt > 1 GeV/c any sign any origin 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 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