HADES coll. meeting, Oct. 31, 2007 Charged pion production in C+C at 1 and 2 A GeV results of data analysis from experiments NOV02 and AUG04 Jehad Mousa and Pavel Tlustý study of charged  meson production in C+C new:  more detailed efficiency study of real data  new method of extrapolation of particle yields to full solid angle  better control of systematic errors report on C+C charged meson analysis

HADES coll. meeting, Oct. 31, 2007 two tracking methods: Kick and Runge-Kutta Kick+RK : inner mdc segment  2 > -1, RK:  2 < 1000, RKAccepted=1, MetaHit matched tracks with TOFINO paddle multiplicity =1 PID - velocity and momentum Track selection and PID

HADES coll. meeting, Oct. 31, 2007 PID efficiency and purity - performance checked using UrQMD - pions identified for momenta 150 < p < 1000 MeV/c

HADES coll. meeting, Oct. 31, 2007 Acceptance and efficiency efficiency calculated using UrQMD as ratio N rectracks /N primary for p,  +,  - in theta vs momentum averaged over phi

HADES coll. meeting, Oct. 31, 2007 “Selfconsistency check” - NOV02 - UrQMD UrQMD input (emitted) and its reconstruction by analysis

HADES coll. meeting, Oct. 31, 2007 “Selfconsistency check” - NOV02 - UrQMD UrQMD input (emitted) and its reconstruction by analysis

HADES coll. meeting, Oct. 31, 2007 Reconstruction efficiency check -- --

HADES coll. meeting, Oct. 31, 2007 Reconstruction efficiency check Errors of individual data points from sectorwise analysis: 1 GeV 2 GeV RMS 3-5% 2-3% maximum up to 20% up to 20% Error of integral yield from sectorwise analysis: 1 GeV 2 GeV RMS 2% 1.5% maximum 7% 4%

HADES coll. meeting, Oct. 31, 2007 Results

HADES coll. meeting, Oct. 31, 2007 dN/d cos(  cm ) ~ 1. + A 2 ∙ cos 2 (  cm ) Center of mass polar distributions

HADES coll. meeting, Oct. 31, 2007 H h h Center of mass polar distributions

HADES coll. meeting, Oct. 31, 2007 Center of mass polar distributions A 2 EXPA 2 UrQMD mom_cm > 200 MeV/c1.05 ± all momenta0.70 exp. data in agreement with UrQMD => A 2 = 0.7 used for PLUTO simulation of dileptons 2 A GeV 1 A GeV A 2 EXPA 2 UrQMD mom_cm > 200 MeV/c0.88 ± all momenta0.56 exp. A2 lower by ~ 40% than UrQMD => A 2 = 0.34 recommended for PLUTO simulation of dileptons

HADES coll. meeting, Oct. 31, 2007 Brockman et al. Ar+KCl 1.8 AGeV central collisions: Brockman: similar A 2 = 0.52 but different A2 dependence on momentum FOPI NPA 781 (2007) shows the same anisotropy for Ca+Ca 1.93 A GeV HADES 2 A GeV Center of mass polar distributions

HADES coll. meeting, Oct. 31, 2007 m T distributions Fitting of m T spectra measured at midrapidity by a Bolzmann distribution with one or two slope function Inverse slope shows temperature of thermal source

HADES coll. meeting, Oct. 31, 2007 m T distributions C+C 1 A GeV

HADES coll. meeting, Oct. 31, 2007 m T distributions C+C 2 A GeV

HADES coll. meeting, Oct. 31, 2007 m T distributions at midrapidity 1 A GeV 2 A GeV 1 A GeV 2 A GeV H H

HADES coll. meeting, Oct. 31, 2007 Fits of p t by 1 or 2 slopes

HADES coll. meeting, Oct. 31, 2007 m T distributions

HADES coll. meeting, Oct. 31, 2007 m T distributions 1 A GeV 2 A GeV HADES T  + = 58 ± 1 T  - = 58 ± 1 T  + = 50 ± 10; 89.5 ± 2.1 T  - = 49 ± 5; 86 ± 3 Kaos T  - = 45 ± 3; 62 ± 3T  - = 40 ± 3; 86 ± 3 Taps T  0 = 54 ± 3T  0 = 83 ± 2 (one slope!)

HADES coll. meeting, Oct. 31, 2007 Rapidity distributions

HADES coll. meeting, Oct. 31, 2007 Extrapolation in p t

HADES coll. meeting, Oct. 31, 2007 Extrapolation in p t

HADES coll. meeting, Oct. 31, 2007 Rapidity distributions symmetrized

HADES coll. meeting, Oct. 31, 2007 Rapidity distributions

HADES coll. meeting, Oct. 31, 2007 Rapidity distributions symmetrized

HADES coll. meeting, Oct. 31, 2007 LVL1 trigger events - efficiency corrected within HADES acceptance and extrapolated to full solid angle Pion multiplicities I Extrapolation to all rapidities A – based on UrQMD B – based on PLUTO

HADES coll. meeting, Oct. 31, 2007 PLUTO simulations Variations of extrapolation factor within 3% for both 1 and 2 A GeV data

HADES coll. meeting, Oct. 31, 2007 LVL1 trigger events - efficiency corrected, within HADES acceptance Systematic errors from reconstruction efficiency? 1)N(p+d) exp /N(p) UrQMD same within 6% 2)track multiplicity distributions Exp vs UrQMD reasonably agree 3) sectorwise analysis - error within 5% Pion multiplicities II LVL1 trigger events extrapolation from HADES acceptance to 4  and all momenta - using UrQMD and measured anisotropy => M  = 0.53 for 1 A GeV and 1.29 for 2 A GeV - used for normalization of di-lepton spectra Systematic errors ? - possibly small, extrapolation factor only ~ 1.5, study using PLUTO show small deviations, still 10% difference between UrQMD and PLUTO

HADES coll. meeting, Oct. 31, 2007 Pion multiplicities III centrality selection by the LVL1 trigger: estimate of N part : 8.6 and 8.4 for 1 and 2 A GeV

HADES coll. meeting, Oct. 31, 2007 Pion multiplicities per participant 1 A GeV 2 A GeV HADES ± ± Kaos ± ± ?? Taps (  0 ) ± %0.138 ± %

HADES coll. meeting, Oct. 31, 2007 Summary charged  meson production from C+C at 1 and 2 A GeV studied new results: multiplicities - in large acceptance polar anisotropies - momentum dependence m T fits - one vs two slopes rapidity distributions - rapidity width

HADES coll. meeting, Oct. 31, 2007 Backup slides

HADES coll. meeting, Oct. 31, 2007 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

HADES coll. meeting, Oct. 31, 2007 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 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: 75% LVL1 trigger + 25% LVL2 trigger 20 M events (gen2 dst’s) used for analysis (day 250, 1st level trigger events) UrQMD simulations - 47 M events (gen2) used for parameter production 20 M events (gen2) used for analysis

HADES coll. meeting, Oct. 31, 2007 Theta_cm distributions - Kick vs RK dN/d cos(  cm ) ~ 1. + A 2 ∙ cos 2 (  cm )

HADES coll. meeting, Oct. 31, 2007 Kick track multiplicities - exp vs UrQMD

HADES coll. meeting, Oct. 31, 2007 p t distributions - exp vs UrQMD vs PLUTO midrapidity