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