Table of contents:

Hadron contamination study by using E/p

Studied hadron contamination at high pT. The contamination estimated with Gaussian + exponent fitting doesn't work at high pT. In the current analysis, it is around 20-30 % at pT > 5 GeV/c. Here we checked whether the contamination is high at high pT. The method of the study is following

  • first fit the E/p and find the mean and sigma of the distribution
  • Calculate yields
    • Up = Integral(m,nXsigma), Dw = Integral(-nXsigma,m), All = Intergal(-nXsigma, nXsigma)
    • here n goes from 1 to 3, m is mean of the distribution
  • Calculate Up/All and Dw/All
  • if the contamination is high Dw/All >> 0.5

The E/p distribution with the fitting curve

Pic_eop_fit_expgau_v2.png"

  • Fig. E/p distribution in pT bins. The distributions are fit with Gaussian + Exponent. Mean and SIgma were extracted from the fitting. The red line indicated 2 sigma (mean+- 2 sigma) position and the blue line indicates 3 sigma position.

Mean position of the distribution as a function of pT

Pic_mean_data.png"

  • Fig. E/p mean position as a function of pT.

Sigma of the distribution as a function of pT

Pic_sig_data.png"

  • Fig. E/p sigma position as a function of pT.

Yields for 1 sigma, 2sigma and 3 sigma cuts of E/p.

Pic_nSigYield.png"

  • Fig. Raw electron yields with 3 different n Sigma cuts (+-1, +-2 and +-3).

The relative ratios of integrals in the upward vs downward vs total integrals of the signal within the E/p peak

Pic_nSigYield.png"

Pic_half_eop_ratio.png"

Summary

  • The E/p mean deviates from 1.
    • Issues with the fit (Gauss+bg) - Shingo is now working on that
    • EMCal: calibration
    • EMCal: residual non-linearities (low-pT)
      • from the test beam this effect should be minimal at 2 GeV
      • however, the cluster cuts and the ZS cuts in the data analysis can induce small non-linearities beyond 2 GeV
      • hadron contamination at low-pT
      • tracking: bremstrahlung at high-pT

  • The E/p sigma goes from max 8.5% at low-pT to 5.5% at 5.5 GeV (3% at 6.5 GeV)
    • this behavior is not unexpected - actually consistent with the beam test results and tracking pT-resolution (however small in this kinematic regime)

  • for 1sigma: 10% effect for all pT's
    • for 2 and 3 sigma: from 1-few% effect at low-pT to 10% max at high-pT (max deviation ~20% at 5.5 GeV but suffering from the stat uncertainty) - average: ~4%
    • important note: the actual signal for the analysis is well within 3sigma and the systematic uncertainty for the related to these effects is driven by the 3sigma selection

Raw electron comparison

Compared electron yields between n sigma cut (-3 sigma < E/p < 3 sigma) & fix cut (0.8 < E/p < 1.3)

Pic_Raw_yield_eta.png"

Ratio (sigma/fix)

Pic_Raw_yield_eta_ratio.png"

Comparison E/p fix (0.8-1.3) & 3 sigma yield after efficiency correction

Pic_Raw_yield_eta_ratio.png"

Pic_Raw_yield_eta_ratio.png"

  • ratio is 1 with in error
  • ~5 % difference at low pT due to 3 sigma position on the hadron tail.

nSIgma dE/dx efficiency

Estimated efficiency of nSigma dE/dx cut (-1.5 < nSigma < 3.0 cut) by fitting the distribution with double Gaussian.

nSIgma distribution after applying E/p cut.

Pic_nSigYield.png"

nSIgma efficiency (-1.5 < nSigma < 3.0) from the fitting

Pic_nSigYield.png"

nSigma efficiency (-1.5 < nSigma < 3.0) from some different cuts for eID.

Pic_nSigYield.png"

nSigma efficiency from different variation.

Pic_nSigYield.png"

Summary

  • the fits look reasonable at low-pT, however the high-pT systematics will suffer from the statistics
  • the nSIgma efficiency (-1.5 < nSigma < 3.0) extracted from the fits is constant at 93% (for all pT's)
    • expected from a Gaussian distribution
  • the uncertainties extracted from variations of charge selection, rapidity ranges and E/p range show few to max 9.5% (relative) deviation
  • note here is that the ranges for E/p taken within 0.8 - 1.0 and 1.3 E/p are overestimating the uncertainty due to limited statistics at high pT.

V0 & MC efficiency for EMCal

Checked eID efficiency from EMCal (matching + E/p) by using V0 and MC.

* V0 cut

  • v0trackCuts->CreateStandardCuts();
  • v0trackCuts->SetMinNClustersTPC(120);
  • v0trackCuts->SetMinNClustersTPCPID(80);
  • v0trackCuts->SetMinRatioTPCclusters(0.6);
  • v0trackCuts->SetTPCmodes(AliHFEextraCuts::kFound, AliHFEextraCuts::kFoundOverFindable);
  • v0trackCuts->SetMinNClustersITS(1);
  • v0trackCuts->SetCutITSpixel(AliHFEextraCuts::kAny);
  • v0trackCuts->SetCheckITSLayerStatus(kFALSE);
  • v0trackCuts->UnsetVertexRequirement();

* Used MC sample ; 10f6a (MB)

Eta dependence

half E/p (E/p > mean)

Efficiency and Raw yields in eta range

-0.6<y<0.6 (half E/p > mean)

Pic_eff_eta3.png"

-0.6<y<-0.2 (half E/p > mean)

Pic_eff_eta0.png"

-0.2<y<0.2 (half E/p > mean)

Pic_eff_eta1.png"

0.2<y<0.6 (half E/p > mean)

Pic_eff_eta2.png"

ratios

1. V0 (eta window / full eta)

Pic_eff_ratio_eta_V0.png"

2. MC (eta window / full eta)

Pic_eff_ratio_eta_MC.png"

full E/p (0.8 < E/p < 1.3)

Efficiency and Raw yields in eta range

-0.6<y<0.6 (0.8< E/p < 1.3)

Pic_eff_eta3.png"

-0.6<y<-0.2 (0.8< E/p < 1.3)

Pic_eff_eta0.png"

-0.2<y<0.2 (0.8< E/p < 1.3)

Pic_eff_eta1.png"

0.2<y<0.6 (0.8 < E/p < 1.3)

Pic_eff_eta2.png"

ratios

1. V0 (eta window / full eta)

Pic_eff_ratio_eta_V0.png"

2. MC (eta window / full eta)

Pic_eff_ratio_eta_MC_full_v2.png"

comparison 0.8 <E/p < 1.3 & E/p > mean

Comparison 1

MC/V0 in different windows

Pic_eff_competa_half.png"

Pic_eff_competa_full.png"

Comparison 2

efficiency from 0.8 <E/p < 1.3 is scaled by 0.5

-0.6<y<0.6

Pic_eff_eta3.png"

-0.6<y<-0.2

Pic_eff_eta0.png"

-0.2<y<0.2

Pic_eff_eta1.png"

0.2<y<0.6

Pic_eff_eta2.png"

V0 efficiency without E/p cut (Track matching)

Pic_V0matchEff.png"

Pic_V0matchEff_all.png"

V0 efficiency for E/p cut

Pic_V0matchEff.png"

Pic_V0matchEff_all.png"

MC efficiency without E/p cut (Track matching)

Pic_MCmatchEff.png"

Pic_MCmatchEff_all.png"

MC efficiency for E/p cut

Pic_MCmatchEff.png"

Pic_MCmatchEff_all.png"

V0 & MC matching & E/p efficiency comparison (|y|<0.6)

Pic_V0MCeffFullComp.png"

Summary

  • the studies are done in pT of the electrons, two E/p cuts (E/p > mean --- pure electron sample, 0.8 < E/p < 1.3) and three selections of rapidity: -0.6<y<0.2; -0.2<y<0.2; 0.2<y<0.6
  • general note is that statistics limits the clarity of the conclusions, however:
  • V0/MC in rapidity windows indicates that
    • a small relative rapidity dependence of V0 efficiency, the ratio is increasing from negative eta to positive eta especially low pT. The trend is not only E/p > mean but also 0.8 < E/p < 1.3.
    • the observed deviation at high pT is mostly driven by the positive rapidity interval - relative 20% effect and above => the V0 efficiency is lower at y>0

  • similar observation can be drawn from the purified/all electron studies but the effect on the order of 15%
  • eta window / full eta ratio also indicates the eta dependence in V0 efficiency.

phi dependence

half E/p (E/p > mean)

Efficiency and Raw yields

1. selected half E/p distribution - E/p greater than mean of the distribution

80<phi<100 (half E/p > mean)

Pic_eff_eta3.png"

100<phi<120 (half E/p > mean)

Pic_eff_eta0.png"

full E/p (0.8<E/p <1.3)

Efficiency and Raw yields

2. phi dependence ; 0.8 <E/p < 1.3

80<phi<100 (0.8< E/p < 1.3)

Pic_eff_eta3.png"

100<y<120 (0.8< E/p < 1.3)

Pic_eff_eta0.png"

comparison 0.8 <E/p < 1.3 & E/p > mean

efficiency from 0.8 <E/p < 1.3 is scaled by 0.5

80 < phi < 100

Pic_eff_phi0_comp_v1.png"

100 < phi < 120

Pic_eff_phi1_comp_v1.png"

Summary

  • the studies as a function of the azimuthal angle agree within the stat uncertainties - at least drawing a systematic effect (for V0 vs MC efficiency) is not clear; however it is clear that the V0 efficiency (within the E/p systematics) shows a much stronger pT dependence as compared to MC - especially for the 100 < phi < 120 bin - however, it is impossible to conclude as within the kinematic region of the measurement (above 1.5 GeV) the curves agree and the stat precision above is limited

Track matching comparison

  • Track matching cut ; R = sqrt(deta^{2}+dphi^{2}) < 0.05

Distribution

Pic_Inccomp.png"

Pic_Inccomp.png"

RMS

Pic_Inccomp.png"

Pic_Inccomp.png"

  • low pT ; V0 MC and V0 data is same RMS as Data
  • high pT ; due to statistical limit, it's difficult to make conclusion. But MC is smaller than Data and V0 which is expected efficiency curve.

Comparison HFE cross section between V0 correction and MC correction

V0 vs MC

  • SInce V0 efficiency is lower than MC, the cross section corrected by V0 efficiency is larger than the one corrected by MC. In addition that the HFE cross section is obtained by non-HEE contribution which is large contribution at low pT. This large background enhances the difference. Thus we see the large difference between the two cross section at low pT region.
    • for example, at pT = 2 GeV/c, non-HFE cross section is ~ 0.9 x 10^-3. The MC corrected cross section is ~1x10^-3, and V0 corrected cross section is ~ 1.2 x 10^-3. After subtracting non-HFE cross section, it makes X3 difference

  • HFE cross section corrected with MC and V0 is consistent within the uncertainty.

Pic_Inccomp.png"

Pic_HFEcomp.png"

Comparison with nSigma TPC half

Pic_HFEcomp.png"

Conclusion

  • V0 & MC indicates rapidity dependence of the efficiency (still working)
  • the MC efficiency is under better control
  • from the comparison to V0 we see a 5-15% relative discrepancy, and this should be taken into the systematic uncertainties, however further studies with a much larger data sample
  • also, the 15% uncertainty seems to be an overestimation in this case as this is a max deviation and is strongly suffers from the statistics of the data sets

-- ShingoSakai - 27-Jan-2012

Topic attachments
I Attachment History Action Size Date Who Comment
C source code filec Comp_eta_eta_eff.C r1 manage 4.7 K 2012-01-29 - 12:58 Ssakai  
Unknown file formatroot MCeopEff1_phi.root r1 manage 5.7 K 2012-01-28 - 22:54 Ssakai  
PNGpng Pic_HFEcomp.png r2 r1 manage 18.3 K 2012-02-05 - 15:04 Ssakai  
PNGpng Pic_HFEcompHalf_ol.png r1 manage 19.4 K 2012-02-06 - 14:18 Ssakai  
PNGpng Pic_HFEcomp_v1.png r2 r1 manage 18.6 K 2012-02-05 - 15:48 Ssakai  
PNGpng Pic_HFEfixsig_comp2.png r1 manage 20.6 K 2012-02-06 - 23:42 Ssakai  
PNGpng Pic_Inccomp.png r6 r5 r4 r3 r2 manage 13.6 K 2012-02-05 - 15:19 Ssakai  
PNGpng Pic_Inccomp_v1.png r1 manage 19.0 K 2012-02-05 - 15:42 Ssakai  
PNGpng Pic_Inclusive_eopcutdep.png r1 manage 9.8 K 2012-02-04 - 19:00 Ssakai  
PNGpng Pic_MCEopEff.png r1 manage 14.2 K 2012-02-01 - 00:15 Ssakai  
PNGpng Pic_MCEopEff_all.png r2 r1 manage 12.0 K 2012-02-02 - 10:06 Ssakai  
PNGpng Pic_MCmatchEff.png r1 manage 14.6 K 2012-02-01 - 00:15 Ssakai  
PNGpng Pic_MCmatchEff_all.png r3 r2 r1 manage 12.3 K 2012-02-02 - 10:06 Ssakai  
PNGpng Pic_Raw_yield_eta.png r3 r2 r1 manage 16.0 K 2012-02-01 - 17:10 Ssakai  
PNGpng Pic_Raw_yield_eta_2sig.png r1 manage 14.4 K 2012-02-01 - 16:46 Ssakai  
PNGpng Pic_Raw_yield_eta_ratio.png r1 manage 21.4 K 2012-01-31 - 22:34 Ssakai  
PNGpng Pic_Rmatch_highRMS.png r2 r1 manage 7.8 K 2012-02-04 - 23:39 Ssakai  
PNGpng Pic_Rmatch_highRMSv1.png r1 manage 10.5 K 2012-02-04 - 23:57 Ssakai  
PNGpng Pic_Rmatch_lowRMS.png r1 manage 8.3 K 2012-02-04 - 23:13 Ssakai  
PNGpng Pic_Rmatch_lowRMSv1.png r1 manage 10.2 K 2012-02-04 - 23:58 Ssakai  
PNGpng Pic_V0EopEff.png r1 manage 14.4 K 2012-01-31 - 14:54 Ssakai  
PNGpng Pic_V0MCeffFullComp.png r1 manage 17.3 K 2012-02-01 - 16:25 Ssakai  
PNGpng Pic_V0eopEff_all.png r2 r1 manage 12.3 K 2012-02-01 - 14:17 Ssakai  
PNGpng Pic_V0matchEff.png r1 manage 14.8 K 2012-01-31 - 11:38 Ssakai  
PNGpng Pic_V0matchEff_all.png r2 r1 manage 12.1 K 2012-02-01 - 14:17 Ssakai  
PNGpng Pic_YieldRatio.png r1 manage 13.1 K 2012-01-27 - 16:09 Ssakai  
PNGpng Pic_Yield_Ratio_eopcut.png r2 r1 manage 9.9 K 2012-02-02 - 09:58 Ssakai  
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PNGpng Pic_eff_competa_full.png r2 r1 manage 17.6 K 2012-01-29 - 16:17 Ssakai  
PNGpng Pic_eff_competa_full_v1.png r1 manage 16.3 K 2012-02-01 - 09:46 Ssakai  
PNGpng Pic_eff_competa_full_v2.png r1 manage 15.3 K 2012-02-01 - 19:00 Ssakai  
PNGpng Pic_eff_competa_half.png r1 manage 18.0 K 2012-01-29 - 15:36 Ssakai  
PNGpng Pic_eff_competa_half_v1.png r1 manage 16.9 K 2012-02-01 - 09:31 Ssakai  
PNGpng Pic_eff_competa_half_v2.png r1 manage 15.4 K 2012-02-01 - 18:58 Ssakai  
PNGpng Pic_eff_eta0.png r3 r2 r1 manage 21.8 K 2012-01-27 - 20:21 Ssakai  
PNGpng Pic_eff_eta0_comp.png r2 r1 manage 20.3 K 2012-01-28 - 00:58 Ssakai  
PNGpng Pic_eff_eta0_full.png r1 manage 12.4 K 2012-01-27 - 21:52 Ssakai  
PNGpng Pic_eff_eta1.png r3 r2 r1 manage 21.6 K 2012-01-27 - 20:22 Ssakai  
PNGpng Pic_eff_eta1_comp.png r2 r1 manage 20.6 K 2012-01-28 - 00:58 Ssakai  
PNGpng Pic_eff_eta1_full.png r1 manage 22.0 K 2012-01-27 - 21:52 Ssakai  
PNGpng Pic_eff_eta2.png r3 r2 r1 manage 21.5 K 2012-01-27 - 20:22 Ssakai  
PNGpng Pic_eff_eta2_comp.png r2 r1 manage 20.1 K 2012-01-28 - 00:59 Ssakai  
PNGpng Pic_eff_eta2_full.png r1 manage 22.3 K 2012-01-27 - 21:52 Ssakai  
PNGpng Pic_eff_eta3.png r3 r2 r1 manage 21.8 K 2012-01-27 - 20:22 Ssakai  
PNGpng Pic_eff_eta3_comp.png r2 r1 manage 19.6 K 2012-01-28 - 00:59 Ssakai  
PNGpng Pic_eff_eta3_full.png r1 manage 22.1 K 2012-01-27 - 21:52 Ssakai  
PNGpng Pic_eff_phi0.png r1 manage 21.5 K 2012-01-28 - 22:32 Ssakai  
PNGpng Pic_eff_phi0_comp.png r1 manage 22.0 K 2012-01-29 - 16:05 Ssakai  
PNGpng Pic_eff_phi0_comp_v1.png r1 manage 22.0 K 2012-01-29 - 16:24 Ssakai  
PNGpng Pic_eff_phi0_full.png r1 manage 21.9 K 2012-01-28 - 22:43 Ssakai  
PNGpng Pic_eff_phi1.png r1 manage 21.5 K 2012-01-28 - 22:32 Ssakai  
PNGpng Pic_eff_phi1_comp.png r1 manage 22.6 K 2012-01-29 - 16:05 Ssakai  
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PNGpng Pic_eff_ratio_eta_MC.png r1 manage 13.9 K 2012-01-29 - 13:13 Ssakai  
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PNGpng Pic_eff_ratio_eta_V0.png r1 manage 14.7 K 2012-01-29 - 13:13 Ssakai  
PNGpng Pic_eff_ratio_eta_V0_full.png r1 manage 14.4 K 2012-01-29 - 13:27 Ssakai  
PNGpng Pic_eff_ratio_eta_V0_full_v1.png r1 manage 13.3 K 2012-02-01 - 09:52 Ssakai  
PNGpng Pic_eff_ratio_eta_V0_full_v3.png r1 manage 13.7 K 2012-02-01 - 18:34 Ssakai  
PNGpng Pic_eff_ratio_eta_V0_v1.png r1 manage 13.3 K 2012-02-01 - 09:34 Ssakai  
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PNGpng Pic_eop_fit_expgau.png r1 manage 29.0 K 2012-01-27 - 14:16 Ssakai  
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PNGpng Pic_nSigYield.png r2 r1 manage 12.8 K 2012-01-28 - 16:11 Ssakai  
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PNGpng Pic_nSigYield_ratio_v1.png r1 manage 11.6 K 2012-02-01 - 07:30 Ssakai  
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PNGpng Pic_nSig_eff.png r1 manage 9.0 K 2012-01-28 - 17:24 Ssakai  
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Topic revision: r48 - 2012-02-22 - Ssakai
 
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