hadron production in c+c at 1 and 2 a gev analysis of data from experiments nov02 and aug04 for high...
TRANSCRIPT
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 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 + 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*106 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
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
• 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 selectionTrack selection
Results of hadron ID - NOV02Results of hadron ID - NOV02
Efficiency and purity - NOV02Efficiency and purity - NOV02
good up to 1000 MeV/c
Spectrometer acceptanceSpectrometer acceptance Acceptance+efficiency calculated
from UrQMD data as ratio
Nrectracks/Nprimary
for p, +,- in theta vs momentum
averaged over phi
Corrected particle yields - NOV02 - Corrected particle yields - NOV02 -
UrQMDUrQMD
),( ),(
),( ),(),(
pEpA
pPpNpN identified
corr
UrQMD input (emitted) and its reconstruction by analysis
Particle yields - NOV02 sec. No.0Particle yields - NOV02 sec. No.0
Momentum distribution
Theta distribution
Momentum distribution
Theta distribution
Particle yields - NOV02 sec. No.3Particle yields - NOV02 sec. No.3
Negative tracks - NOV02Negative tracks - NOV02theta 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 Particle yields - NOV02 - selected regionregion
NOV02 particle distributions in c.m.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 *2.482.37 ± 0.24p
0.96 ± 0.100.800.77 ± 0.08–
0.96 ± 0.100.770.74 ± 0,07+
ratioNexp / Nsim
UrQMDexperiment
(± bias error)
efficiency corrected, within HADES acceptance
1st level trigger events
p+d)exp/psim
NOV02 particle yields per event - RKNOV02 particle yields per event - RK
Nov02 Nov01
yield/event 0.77 0.79
correction to 4 1.46 1.61
yield corr. to 4 1.12 1.27
correction totrigger
0.71 0.76
norm. to baryons ? 0.92
min bias yield 0.80 0.89
• UrQMD yields to- 1.15event (1st level trigger) • 0.82event (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 - RKNOV02 particle yields per event - RK
Momentum distribution
Theta distribution
Corrected particle yields - AUG04 sec. Corrected particle yields - AUG04 sec. No.1No.1
theta distributions
differences between sectors,
gaps in SHOWER+TOFINO region
SEC 0
SEC 3
Negative tracks - AUG04Negative tracks - AUG04
analysis check - comparison of 2 RK analyses
Particle yields - AUG04 sec. No.1Particle yields - AUG04 sec. No.1
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+
ratioNexp / Nsim
simulationexperiment
(± bias error)
p+d)exp/psim
AUG04 particle yields per event - RKAUG04 particle yields per event - RK
efficiency corrected, within HADES acceptance
1st level trigger events
Aug04 Nov01
yield/event 0.31 0.79
correction to 4 1.49 1.61
yield corr. to 4 0.46 1.27
correction totrigger
0.69 0.76
norm. to baryons ? 0.92
min bias yield 0.32 0.89
• UrQMD yields to- 0.52event (1st level trigger) • 0.36event (no bias)
• N = 0.34 ± 0.02 TAPS• N = 0.48 ± 0.02 M. Gadzicki et al. (N+N1AGeV)
AUG04 particle yields per event - RKAUG04 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?
RK kick
yield/event 0.77 0.79
correction to 4 1.46 1.44
yield corr. to 4 1.12 1.14
correction totrigger
0.71 0.71
norm. to baryons ? ?
min bias yield 0.80 0.81
• UrQMD yields to- 1.15event (1st level trigger) • 0.82event (no bias)
• N = 0.83 ± 0.08 TAPS• N = 0.77 ± 0.07 KAOS
NOV02 particle yields per event - NOV02 particle yields per event -
kick+RKkick+RK
RK kick
yield/event 0.31 0.31
correction to 4 1.49 1.41
yield corr. to 4 0.46 0.44
correction totrigger
0.69 0.69
norm. to baryons ? ?
min bias yield 0.32 0.30
• UrQMD yields to- 0.52event (1st level trigger) • 0.36event (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 - AUG04 particle yields per event -
kick+RKkick+RK
NOV02 - META and track multiplicity
8% of„empty events“ in EXP
Mean multiplicityin EXP greater than in UrQMD -
different centrality or fake tracks in EXP ?
10% of„empty events“ in EXP
Mean multiplicityin 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 NOV02 gen3 and gen4 QAQA
•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 gen3SYS 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(ptrack - p)vs ptrack p = Mp * *
SYS 1 SYS 1SYS 0 SYS 0
KICK
SPLINE
RK