Studies for Run2B Silicon project - High Lumonosity Scenario (Pat )

Studies performed using Run2a simulation

Tools

Full simulation and reconstruction of Run2a detector has been used to generate and reconstruct 100 ttbar events. COT tracking has been performed with the merged set of tracks, Silicon tracking is done with "Outside-In" algorithm (RunI style by Weiming Yao) in 2d only.
The denominator is defined using only MonteCarlo quantities:

Particle stable or decaying outside COT: (f_r>140 cm) or (f_r ==-1);
Particle produced inside the beam-pipe: i_r<2.0 cm;
Particle with |d0|<2.0cm and |z0|<60cm;
Pt>0.4 GeV/c;
Particle not a looper: Nh(COT)<97;
Perfect Tracking used to pick a well reconstructed COT track;
N_ax(SI)>5 (released by the MC particle);
fiducial in Silicon (at least one hit in layer 0, and at least one hit in ISL)

Efficiency definition

The efficiency is defined looking at the difference of fitted track parameters and the OBSP helix.
The cuts are very wide:

Found track: Nax(SI)>3;
|Delta(Curv)|<0.00025 cm-1
|Delta(d0)|<0.05 cm
|Delta(z0)|<0.1 cm

Note: given the above definition, the behavior of the efficiency is correlated to the amount of non-gaussian tails of the impact parameter distribution.

CAVEATS

Is MBR generating reproducing what we see in the data?

Results

CUTS	tt + 0 extra Min bias	tt + 5 extra min bias	tt + 10 extra min bias	tt + 15 extra min bias
All generated particles	34958	133421	260064	337410
Denominator Tracks	3126	5417	6560	5081
Found Silicon tracks	2774 (88.7%)	4646 (85.8%)	5660 (86.3%)	4402 (86.6%)
Good Silicon tracks	2724(87.1%)	4497 (83.0%)	5286 (80.6%)	4003(78.8%)

Study of hit sharing

We looked at the fraction of hits on fiducial (or b-daughter) tracks that are shared as a function of layer ( i.e. radius) and extra minimum bias interactions. A hit is defined shared for this study when the cluster associated to it has a contribution from another particle charge. Note: the geometric charge deposition model underestimates the cluster width, so the amount of sharing. This is particularly true for L0 where the floating strip is not implemented in this model.

Plots for fiducial particles (pt>0.5GeV): 0mbr , 5mbr , 10mbr , 15mbr ;
Plots for fiducial b- daughterparticles (pt>0.5GeV): 0mbr , 5mbr , 10mbr , 15mbr ,

LAYER	tt +0 MBR	tt +5 MBR	tt +10 MBR	tt + 15MBR
0	0.39	0.42	0.51	0.54
1	0.23	0.24	0.31	0.33
2	0.14	0.14	0.21	0.23
3	0.13	0.11	0.15	0.17
4	0.08	0.07	0.10	0.12
5	0.08	0.08	0.10	0.12
6	0.17	0.17	0.17	0.18
7	0.11	0.11	0.13	0.12

LAYER	tt + 0 MBR	tt + 5 MBR	tt + 10 MBR	tt + 15 MBR
0	0.54	0.63	0.73	0.75
1	0.37	0.46	0.46	0.49
2	0.24	0.24	0.35	0.36
3	0.17	0.13	0.22	0.33
4	0.16	0.07	0.13	0.17
5	0.14	0.11	0.14	0.20
6	0.20	0.21	0.18	0.21
7	0.12	0.12	0.17	0.17

TO DO NEXT

Run Secvtx (need larger sample...farms???)

Patrizi Azzi

Last modified: Mon Jul 22 11:44:06 CDT 2002