Fits of the mt distributions at midrapidity of the real data and UrQMD events:

1. UrQMD source (*.evt file)
2. UrQMD source (*.evt file) passed through the acceptance matrix
3. UrQMD LVL1 events (from GeantKine from UrQMD dst files)
4. UrQMD LVL1 events passed through the acceptance matrix (from GeantKine from UrQMD dst files)
5. "sim" data = UrQMD data fully analyzed (tracking+PID+efficiency corrections)
6. real data

Fitted function is
1/m2t*dN/dmt = C1*exp(-mt/T1) + C2*exp(-mt/T2)

Range of fit is 50 ≤ mt-mpi < 550. This gives the same results for UrQMD data without and with the acceptance filter for both pi+ and pi-. For pi- we can decrease the lower range to 25, and the fit result do not change significantly for the real and "sim" data.
Only statistical errors are taken into account. Please note the chi2 value of fits.
T1/T2 shows ratio of areas of one slope components of te distribution.
  chi2/NDF T1 T2 T1/T2
pi+ urqmd primary 79/16 30.6+-0.4 87.7+-0.1 0.15
pi- urqmd primary 153/16 31.3+-0.3 87.7+-0.1 0.16
pi+ urqmd LVL1 30/16 41.3+-0.6 90.3+-0.2 0.24
pi- urqmd LVL1 61/16 40.8+-0.5 89.9+-0.2 0.24
pi+ urqmd sim 352/16 45.1+-1.0 91.3+-0.4 0.25
pi- urqmd sim 145/16 40.0+-0.9 90.7+-0.3 0.23
pi+ exp 373/16 53.7+-0.5 93.6+-0.6 1.01
pi- exp 538/16 48.6+-0.3 91.7+-0.5 1.20

now fit result of the real data if we assume the points errors 2.5% (from differences between distribution from different sectors)
pi+ exp 17.0/16 47.7+-3.3 88.7+-1.7 0.60
pi- exp 11.3/16 50.3+-2.0 94.0+-2.5 1.42

Some conclusions:

1)
UrQMD primary and UrQMD LVL1 differ - we get higher slopes for LVL1 -
looks that selection on sentrality makes pi mesons "harder".
2)
UrQMD LVL1 and "sim" agree - it shows that all analysis does not spoil the urqmd original distributions.

Here are the figures with fits (results shown also in previous table):
  • UrQMD primary (from *.evt files):
    UrQMD primary (from *.evt files)

  • UrQMD LVL1 (from urqmd dst's GeantKine):
    UrQMD LVL1 (from urqmd dst's <a class=GeantKine)" width="966" height="474" />

  • "sim" - full analysis of UrQMD dsts:

  • real data - statistical errors:
    real data - statistical errors

  • real data - errors 2.5% (good chi2):
    real data - errors 2.5% (good chi2)

-- PavelTlusty - 31 Mar 2008
Topic attachments
I Attachment Action Size Date Who Comment
arkcl_mtfit_LVL1urqmd_50.gifgif arkcl_mtfit_LVL1urqmd_50.gif manage 25.3 K 01 Apr 2008 - 13:53 PavelTlusty UrQMD LVL1 (from urqmd dst's GeantKine)
arkcl_mtfit_exp_50.gifgif arkcl_mtfit_exp_50.gif manage 26.4 K 01 Apr 2008 - 13:55 PavelTlusty real data - statistical errors
arkcl_mtfit_exp_50_error2.5.gifgif arkcl_mtfit_exp_50_error2.5.gif manage 25.8 K 01 Apr 2008 - 13:56 PavelTlusty real data - errors 2.5% (good chi2)
arkcl_mtfit_sim_50.gifgif arkcl_mtfit_sim_50.gif manage 25.3 K 01 Apr 2008 - 13:54 PavelTlusty "sim" - full analysis of UrQMD dsts
arkcl_mtfit_urqmd_50.gifgif arkcl_mtfit_urqmd_50.gif manage 25.0 K 01 Apr 2008 - 13:52 PavelTlusty UrQMD primary (from *.evt files)
Topic revision: r4 - 03 Apr 2008, PavelTlusty
 
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