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Hadron production in C+C at 1 and 2 A GeV analysis of data from experiments NOV02 and AUG04 for high resolution tracking (Runge-Kutta tracks) Pavel Tlustý, NPI Řež HADES Coll. Meeting XVI Dresden, April 5, 2006 summary of charged meson production in C+C
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Experimental and analysis details November 2002 C+C 2 AGeV 200*10 6 events: 56% LVL1 trigger + 44% LVL2 trigger only 2 sectors with 4 chambers + RK tracking used in the analysis 20 M events (gen4 dst’s) used for analysis (days 348-350, 1st level trigger events) UrQMD simulations - 47 M events (gen4) used for parameter production 20 M events (gen4) used for analysis August 2004 C+C 1 AGeV 650*10 6 events: 50% LVL1 trigger + 50% LVL2 trigger 20 M events (gen1 dst’s) used for analysis (days 251+253, 1st level trigger events) UrQMD simulations - 47 M events (gen1) used for parameter production 20 M events (gen1) used for analysis
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Principle: for each track a probability that it is of a particle type h is calculated, for all possible particle types Bayes theorem implemented cut on the resulted probability set to decide on PID Input: for each track (track candidate) with a given momentum we have a set of independent measured variables in HADES: velocity, energy loss, RICH response, MDC hit, SHOWER response Output: - a probability, that a given track corresponds to the particle type h - efficiency and purity for a selected cut Particle Identification Method
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Runge-Kutta tracks matched to META inner mdc segment 2 > -1, RK 2 < 1000, SplineAccepted=1 tracks with TOFINO paddle multiplicity =1 for NOV02 only sectors No. 0 and 3 Track selection
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Results of hadron ID - NOV02
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Efficiency and purity - NOV02 good up to 1000 MeV/c
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Spectrometer acceptance Acceptance+efficiency calculated from UrQMD data as ratio N rectracks /N primary for p, +, - in theta vs momentum averaged over phi
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Corrected particle yields - NOV02 - UrQMD UrQMD input (emitted) and its reconstruction by analysis
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Particle yields - NOV02 sec. No.0 Momentum distribution Theta distribution
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Momentum distribution Theta distribution Particle yields - NOV02 sec. No.3
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Negative tracks - NOV02 theta distributions: differences between sectors and gaps already in tracks distribution - effect of subdetectors efficiency SEC 0 SEC 3
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momentum distribution theta distribution Particle yields - NOV02 - selected region
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NOV02 particle distributions in c.m. UrQMD input (emitted) and reconstruction by analysis mom_cm > 200 MeV/c
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NOV02 - distributions in theta_cm
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NOV02 - distribution in mom_cm - UrQMD
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NOV02 - distributions in p_cm - EXP
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no d in UrQMD0.24 ± 0.02d 1.05 ± 0.11 *2.482.37 ± 0.24p 0.96 ± 0.100.800.77 ± 0.08 –– 0.96 ± 0.100.770.74 ± 0,07 ++ ratio N exp / N sim UrQMDexperiment (± bias error) efficiency corrected, within HADES acceptance 1st level trigger events p+d) exp /p sim NOV02 particle yields per event - RK
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UrQMD yields to - 1.15 event (1st level trigger) 0.82 event (no bias) N = 0.83 ± 0.08 TAPS N = 0.77 ± 0.07 KAOS HADES acc - 1st level trigger - 1st level trigger min. bias NOV02 particle yields per event - RK
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Momentum distribution Theta distribution Corrected particle yields - AUG04 sec. No.1
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theta distributions differences between sectors, gaps in SHOWER+TOFINO region SEC 0 SEC 3 Negative tracks - AUG04
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analysis check - comparison of 2 RK analyses Particle yields - AUG04 sec. No.1
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no d in UrQMD0.42 ± 0.04d 0.90 ± 0.11 *3.212.47 ± 0.25p 0.89 ± 0.100.360.32 ± 0.03 –– 0.88 ± 0.100.340.30 ± 0.03 ++ ratio N exp / N sim simulationexperiment (± bias error) p+d) exp /p sim AUG04 particle yields per event - RK efficiency corrected, within HADES acceptance 1st level trigger events
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UrQMD yields to - 0.52 event (1st level trigger) 0.36 event (no bias) N = 0.34 ± 0.02 TAPS N = 0.48 ± 0.02 M. Gadzicki et al. (N+N1AGeV) AUG04 particle yields per event - RK HADES acc - 1st level trigger - 1st level trigger min. bias
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Summary of “ ” results comparison of low vs high resolution data - theta distributions plotting of EXP/SIM ratio of yields versus momentum comparison of yields check of centrality selection of the 1st level trigger - multiplicity spectra, number of charged baryons per event….
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NOV02 - KICK vs RK Theta distribution sec no.0 Theta distribution sec. no.3
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Theta distribution sec no.1 AUG04 - KICK vs RK
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AUG04 - EXP/SIM ratio of yields vs mom low efficiency for mips?
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UrQMD yields to - 1.15 event (1st level trigger) 0.82 event (no bias) N = 0.83 ± 0.08 TAPS N = 0.77 ± 0.07 KAOS NOV02 particle yields per event - kick+RK
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UrQMD yields to - 0.52 event (1st level trigger) 0.36 event (no bias) most probably >10% yields lost due to low efficiency N = 0.34 ± 0.02 TAPS N = 0.48 ± 0.02 M. Gadzicki et al. (N+N1AGeV) AUG04 particle yields per event - kick+RK
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NOV02 - META and track multiplicity 8% of „empty events“ in EXP Mean multiplicity in EXP greater than in UrQMD - different centrality or fake tracks in EXP ?
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10% of „empty events“ in EXP Mean multiplicity in EXP same as in UrQMD - same centrality ? AUG04 - META and track multiplicity
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Summary and outlook hadron PID analysis (beta vs momentum) performed using kick and runge-kutta tracks for NOV02 and AUG04 experiment meson and baryon yields extracted to be done: problem with track reconstruction efficiency for particles with low energy loss observed, further efficiency corrections needed new dst‘s for AUG04?
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NOV02 gen3 and gen4 QA tracks yields per sector, theta and phi distributions of negative tracks (test of PID) momentum determination - protons, pi- ??
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NOV02 gen3 - negative tracks vs phi large differences between sectors, for spline 15% difference between 2 sectors, kick even worse yields copy distribution of negative tracks should be the same in electron distributions???? SIM EXP
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NOV01 - negative tracks vs phi sec0 not used for analysis much better than Nov02 gen3 EXP SIM
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NOV02 gen4 - negative tracks vs phi much better than Nov02 gen3 SYS 0 SYS 1
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NOV02 gen3 - negative tracks vs theta Sec0 - Inefficiency in theta<30 and theta ~ 65 EXP SEC0 SIM EXP SEC3
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NOV01 - negative tracks vs theta much better than Nov02! EXP SIM
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NOV02 gen4 - negative tracks vs theta differences between sectors SEC 0 SEC 3
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NOV02 gen4 protons: mom_track vs mom_beta (p track - p ) vs p track p = M p * * SYS 1 SYS 0 KICK SPLINE RK
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