Efficiency

• n = number of possible hits.
• k = number of fitted hits.

• |z vertex| < 10 cm.
• |eta| < 1.
• N fitted points > 15.

  Data

  2-d plots

  Figure 1 : Data : CuCu @ 62 GeV	Figure 2 : Data : CuCu @ 200 GeV

  Plot with text for CuCu62 : here
  Plot with text for CuCu200: here

  Efficiency vs pT of these tracks

  Figure 3 : Data : CuCu @ 62 GeV	Figure 4 : Data : CuCu @ 200 GeV

  These plots show the number of fitted hits vs the number of possible hits for each track.
  I select only the tracks which could have a ssd hit, eg in the ssd eta range.
  On this page I get another efficiencies (~ 30 %) for tracks including the ssd only. The difference between the previous plot is that I was selecting only tracks with ssd points and I was requiring no hits in svt.
  Now the efficiencies (~55 %) for the 2 datasets have not this condition, eg I accept tracks w/o svt points.
  

  Efficiency vs pT of these tracks (with errors bars)

  Figure 3-a : Data : CuCu @ 62 GeV	Figure 4-a : Data : CuCu @ 200 GeV

  Log of the errors : Here Drawing : Here

  Simu

  The simulation files are for CuCu @ 200 GeV Hijing.

  2-d plots

  Figure 5 : Data : CuCu @ 200 GeV

  Efficiency vs pT of these tracks

  Figure 6 : Data : CuCu @ 200 GeV

  
  A list of the MuDst files i used is here
  

  Cut on the dca

  From Marco's page, I added a dca cut (dca < 1 cm) : sqrt(pow(mDcaD,2)+(pow(mDcaZ,2)).

  Figure 7 : Data : CuCu @ 62 GeV with dca < 1 cm

  There is small increase for the tracks with pT < 0.5 GeV/c.
  
  

  Evolution of the ssd efficiency with the svt hits

  With the difference observed between when I require no svt hits on tracks and without this condition, I studied all the possible cases :
  • tracks with 1 or 2 or 3 svt fitted hits.
  • tracks with at least 1, at least 2, at least 3 svt fitted hits.

  Figure 8 : tracks with 1 or 2 or 3 svt fitted hits.	Figure 9 : tracks with at least 1, at least 2, at least 3 svt fitted hits.

  From the plot on the left, the ssd efficiency reaches 100 % when the track contains only 1 svt hit; then it decreases to 60 % for tracks with 2 or 3 svt hits.
  From the second plot, the condition changes and I select tracks with a minimum of svt hits. So when the tracks has 1 or more svt hits, the efficiency reaches 80 % and it comes from the mean of the 3 plots shown in the plot of the left.
  

  Details

  The 3 next plots show the 2-d plots for the 9 pT-bins for the cases :
  • only 0 svt hit fitted.
  • only 1 svt hit fitted.
  • only 2 svt hits fitted.
  • only 3 svt hits fitted.

  Figure 10 : tracks with 0 svt fitted hit.	Figure 11 : tracks with only 1 svt fitted hits.

  Figure 12 : tracks with 2 svt fitted hits.	Figure 13 : tracks with only 3 svt fitted hits.

  Evolution of the ssd efficiency with the cut on Z vertex

  August 16th : I cut now on |z vertex| < 5 cm (instead before on |z vertex|< 10 cm)

  --> Compare figure 14 with figure 4-a and figure 15 with figure 6
  There is a small increase in the efficiency.
  Possible reason : the association of the tracks from the tpc with the ssd point could be better in the central region (if z vertex decreases with the same eta cut, the central region decrases too).
  We see the same behaviour as before, that is to siad that the efficiency is better in the simulation than in the data

  Figure 14 : data CuCu 200 GeV.	Figure 15 : simu CuCu 200 GeV.

  August 17th : Final cuts

  The set of cuts applied to the data and simulation are :
  • const Double_t zcut = 5;
  • if (mNHitsFit[k] < 15) continue;
  • if (fabs(Eta[k]) > 1) continue;
  • if (pT[k] < 0.1) continue;
  • Float_t DCA = sqrt(pow(mDcaD[k],2)+pow(mDcaZ[k],2));
    if(DCA>1.0) continue;
  • Double_t phi = 180*Phi[k]/TMat::Pi();
    if(phi>-40 && phi<0) continue;
  
  

  Figure 16 : data CuCu 62 GeV.	Figure 17 : data CuCu 200 GeV.	Figure 18 : simu CuCu 200 GeV.

  Chi^2 of tracks

  I show here the chi^2 of tracks :
  • with 1 fitted hit for 1 possible hit
  • with 0 fitted hit for 1 possible hit

  Figure 19 : data CuCu 62 GeV.	Figure 20 : data CuCu 200 GeV.	Figure 21 : simu CuCu 200 GeV.

  Efficiency vs centrality

  The definition of the multiplicity of tracks I used is here.
  :

  Figure 22 : data CuCu 62 GeV.	Figure 23 : data CuCu 200 GeV.

  Position in Z of the vertex

  The red line represents the position in Z (cm) before cuts and the green is after.
  The cuts are defined here, except the z cut.
  

  Figure 24 : data CuCu 62 GeV.	Figure 25 : data CuCu 200 GeV.	Figure 26 : simu CuCu 200 GeV.

  Number of fitted svt hits

  Figure 27 : data CuCu 62 GeV.	Figure 28 : data CuCu 200 GeV.	Figure 29 : simu CuCu 200 GeV.

  For the low multiplicity

  The idea is to see if when we select with very low multiplicity, the efficiency increases or not.
  

  Multiplicity

  First I plot the multiplicity of tracks for cucu62 and cucu200 with the cut I used.

  Figure 30 : data CuCu 62 GeV.	Figure 31 : data CuCu 200 GeV.

  N_fitted vs N_poss for cucu62

  Figure 32 : 5 < N Tracks < 10	Figure 33 : N Tracks < 5

  Jonathan Bouchet
  Last modified: Sun Oct 15 17:51:41 EDT 2006