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

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 , 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 , 1st level trigger events) UrQMD simulations - 47 M events (gen1) used for parameter production 20 M events (gen1) used for analysis

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

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

Results of hadron ID - NOV02

Efficiency and purity - NOV02 good up to 1000 MeV/c

Spectrometer acceptance Acceptance+efficiency calculated from UrQMD data as ratio N rectracks /N primary for p,  +,  - in theta vs momentum averaged over phi

Corrected particle yields - NOV02 - UrQMD UrQMD input (emitted) and its reconstruction by analysis

Particle yields - NOV02 sec. No.0 Momentum distribution Theta distribution

Momentum distribution Theta distribution Particle yields - NOV02 sec. No.3

Negative tracks - NOV02 theta distributions: differences between sectors and gaps already in tracks distribution - effect of subdetectors efficiency SEC 0 SEC 3

momentum distribution theta distribution Particle yields - NOV02 - selected region

NOV02 particle distributions in c.m. UrQMD input (emitted) and reconstruction by analysis mom_cm > 200 MeV/c

NOV02 -  distributions in theta_cm

NOV02 -  distribution in mom_cm - UrQMD

NOV02 -  distributions in p_cm - EXP

no d in UrQMD0.24 ± 0.02d 1.05 ± 0.11 * ± 0.24p 0.96 ± ± 0.08 –– 0.96 ± ± 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

UrQMD yields to   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

Momentum distribution Theta distribution Corrected particle yields - AUG04 sec. No.1

theta distributions differences between sectors, gaps in SHOWER+TOFINO region SEC 0 SEC 3 Negative tracks - AUG04

analysis check - comparison of 2 RK analyses Particle yields - AUG04 sec. No.1

no d in UrQMD0.42 ± 0.04d 0.90 ± 0.11 * ± 0.25p 0.89 ± ± 0.03 –– 0.88 ± ± 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

UrQMD yields to   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

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….

NOV02 - KICK vs RK Theta distribution sec no.0 Theta distribution sec. no.3

Theta distribution sec no.1 AUG04 - KICK vs RK

AUG04 - EXP/SIM ratio of yields vs mom low efficiency for mips?

UrQMD yields to   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

UrQMD yields to   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

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 ?

10% of  „empty events“ in EXP Mean multiplicity  in EXP same as in UrQMD - same centrality ? AUG04 - META and track multiplicity

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?

NOV02 gen3 and gen4 QA tracks yields per sector, theta and phi distributions of negative tracks (test of PID) momentum determination - protons, pi- ??

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

NOV01 - negative tracks vs phi sec0 not used for analysis much better than Nov02 gen3 EXP SIM

NOV02 gen4 - negative tracks vs phi much better than Nov02 gen3 SYS 0 SYS 1

NOV02 gen3 - negative tracks vs theta Sec0 - Inefficiency in theta<30 and theta ~ 65 EXP SEC0 SIM EXP SEC3

NOV01 - negative tracks vs theta much better than Nov02! EXP SIM

NOV02 gen4 - negative tracks vs theta differences between sectors SEC 0 SEC 3

NOV02 gen4 protons: mom_track vs mom_beta (p track - p  )  vs p track  p  = M p *  *  SYS 1 SYS 0 KICK SPLINE RK