HADES coll. meeting, Oct. 31, 2007 Charged pion production in C+C at 1 and 2 A GeV results of data...
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Transcript of HADES coll. meeting, Oct. 31, 2007 Charged pion production in C+C at 1 and 2 A GeV results of data...
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 http://hades-wiki.gsi.de/cgibin/view/Physics/HadronProduction
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 PIDTrack selection and PID
HADES coll. meeting, Oct. 31, 2007
PID efficiency and purityPID efficiency and purity
- performance checked using UrQMD
- pions identified for momenta 150 < p < 1000 MeV/c
HADES coll. meeting, Oct. 31, 2007
Acceptance and efficiencyAcceptance and efficiency efficiency calculated using UrQMD as
ratio
Nrectracks/Nprimary
for p, +,- in theta vs momentum
averaged over phi
HADES coll. meeting, Oct. 31, 2007
““Selfconsistency check” - NOV02 - Selfconsistency check” - NOV02 -
UrQMDUrQMD
),( ),(
),( ),(),(
pEp
pPpNpN identified
corr
UrQMD input (emitted) and its reconstruction by analysis
HADES coll. meeting, Oct. 31, 2007
““Selfconsistency check” - NOV02 - Selfconsistency check” - NOV02 -
UrQMDUrQMD UrQMD input (emitted) and its reconstruction by analysis
HADES coll. meeting, Oct. 31, 2007
Reconstruction efficiency checkReconstruction efficiency check
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HADES coll. meeting, Oct. 31, 2007
Reconstruction efficiency checkReconstruction 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. + A2 ∙ cos2(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
A2 EXP A2 UrQMD
mom_cm > 200 MeV/c 1.05 ± 0.20 1.08
all momenta 0.70
exp. data in agreement with UrQMD => A2 = 0.7 used for PLUTO simulation of dileptons
2 A GeV
1 A GeV
A2 EXP A2 UrQMD
mom_cm > 200 MeV/c 0.88 ± 0.12 1.45
all momenta 0.56
exp. A2 lower by ~ 40% than UrQMD => A2 = 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 A2 = 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
mmTT distributions distributions
21 /2
/12
1 TmTm
TT
TT eCeCdm
d
m
Fitting of mT 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
mmTT distributions C+C 1 A GeV distributions C+C 1 A GeV
HADES coll. meeting, Oct. 31, 2007
mmTT distributions C+C 2 A GeV distributions C+C 2 A GeV
HADES coll. meeting, Oct. 31, 2007
mmTT distributions at midrapidity 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 pFits of ptt by 1 or 2 slopes by 1 or 2 slopes
HADES coll. meeting, Oct. 31, 2007
mmTT distributions distributions
HADES coll. meeting, Oct. 31, 2007
mmTT distributions distributions
1 A GeV 2 A GeV
HADEST+ = 58 ± 1
T- = 58 ± 1
T+ = 50 ± 10; 89.5 ± 2.1
T- = 49 ± 5; 86 ± 3
KaosT- = 45 ± 3; 62 ± 3 T- = 40 ± 3; 86 ± 3
Taps T0 = 54 ± 3 T0 = 83 ± 2 (one slope!)
HADES coll. meeting, Oct. 31, 2007
Rapidity distributionsRapidity distributions
HADES coll. meeting, Oct. 31, 2007
Extrapolation in pExtrapolation in ptt
HADES coll. meeting, Oct. 31, 2007
Extrapolation in pExtrapolation in ptt
HADES coll. meeting, Oct. 31, 2007
Rapidity distributionsRapidity distributions
symmetrized
HADES coll. meeting, Oct. 31, 2007
Rapidity distributionsRapidity distributions
HADES coll. meeting, Oct. 31, 2007
Rapidity distributionsRapidity distributions
symmetrized
HADES coll. meeting, Oct. 31, 2007
LVL1 trigger events - efficiency corrected
within HADES acceptance and extrapolated to full solid angle
Pion multiplicities IPion multiplicities I
Extrapolation to all rapidities
A – based on UrQMD
B – based on PLUTO
HADES coll. meeting, Oct. 31, 2007
PLUTO simulationsPLUTO 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 IIPion 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 IIIPion multiplicities IIIcentrality selection
by the LVL1 trigger:
estimate of Npart :
8.6 and 8.4 for 1 and 2 A GeV
HADES coll. meeting, Oct. 31, 2007
Pion multiplicities per participantPion multiplicities per participant
1 A GeV 2 A GeV
HADES 0.061 ± 0.007 0.153 ± 0.016
Kaos0.061 ± 0.009 ± ??
Taps ( 0 )0.056 ± 0.004 + 11% 0.138 ± 0.014 + 23%
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
mT 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 implementedcut 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 variablesin 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 MethodParticle Identification Method
HADES coll. meeting, Oct. 31, 2007
Experimental and analysis Experimental and analysis
detailsdetails November 2002 C+C 2 AGeV 200*106 events: 56% LVL1 trigger + 44% LVL2 trigger only 2 sectors with 4 chambers
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*106 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 RKTheta_cm distributions - Kick vs RK
dN/d cos(cm) ~ 1. + A2 ∙ cos2(cm)
HADES coll. meeting, Oct. 31, 2007
Kick track multiplicities - exp vs UrQMD
HADES coll. meeting, Oct. 31, 2007
pt distributions - exp vs UrQMD vs PLUTOmidrapidity
midrapidity