Studies on stand-alone Si tracking with SVT

Alberto, Alessandro, Pierluigi

Here we investigate the possibility to run SVT in the silicon only configuration.

In a scenario with a bigger AM bank we could think about the possibility to store different pattern sets at the same time. Each pattern set is dedicated to different algorithm of pattern recognition.

A pattern set for the usual silicon+XFT hitsand

Silicon only patterns

What can we do with silicon only SVT?

•Increase tracking acceptance in the forward regions (||2) potentially useful for high Pt forward leptons…

•We would be able to select low Pt tracks below the XFT Pt treshold (2 - 1.5 GeV) in the central region.

•Other suggestions?!?

Caveat: this is work in progress !!!

Since we have L2 timing constraints (that are going to be more severe…) the first thing we have to do is try to understand if the corresponding workload for SVT is acceptable

In term of workload we intend to evaluate:

• The average number of Roads in output from the AM corresponding to the wedge with the maximum # Road per event.

• The total number of hit combinations faced by the track fitter in the wedge with maximum # Road per event.

• The average number of tracks in output from the TF considering the wedge with the max number of road per event.

The wedge with max # roads-combinations drives the event timing!

Feelingfor the TF work load

PROS CONS

Road Warrior Kills spurious 4/4 when 5/5 fires ?

Silicon only pattern restricted to the forward regions

Less patterns to be stored, potentially less random pattern firing

Not negligible overlapping with central region

Restricted Luminosity region in pattern generation

less pattern to store in the AM Higher sensitivity to beam movements

Narrower Roads

(I.e. SS size)

Less combinations inside a road Road fake rate?

Less room for other algorithms

Higher Pt threshold in pattern generation

Less patterns needed Selective on physics

Majority logic

(4/5 4/4,5/5)

More efficient More patterns firing

Matching of tracks with other objects in the detector(forward leptons…)

Reduce the combinatorial

Possibility for new trigger selections for forward leptons

Efficient ?

SVTsim configuration:

•Standalone silicon•Enlarged pattern bank (71K coverage 97%)•Wider coverage (-2,2)•4/5 majority logic•Pt > 2 GeV/c•1.2 mm beam spot•SS 12-8-8-8-12•Track GB disabled•Road busting

We begin with the loosest configuration…

Data from SVT test run 152133

Pattern recognition workload

Nroad fuori da AMS Nroad after ghost

Ncomb Ntracks

50 255

82 173

Lepton Matching

Two possibilities:

1. L2 alpha matches SVT tracks to plug leptons

2. SVT pattern recognition seeded by plug leptons

Easiest starting point:

Plug muons + SVT track

Evaluate rejection

If ok then test 2. on svtsim

Forward Muon Triggers

•BMU * BSU(F) 1<<1.25

•BMU*BSU(R)*TSU 1.25<<1.5

Studies based on run # 167715:

•L2_RL1.3HZ_L1_BMU10_BSUR_TSUO_&_CLC_v-1 (REAR)

•L2_RL0.7HZ_L1_BMU10_PT11_v-1 (FRONT)

TSU

BSU

BSU(R)

BSU(F)

Matching Performances

Input Events 625

Muon objects

2389 Pt>4 Eta matching

Pt>4 and eta matching

SVT confirmed

825 409 480 230

Events selected

248 165 184 115

Avg. #of SVT tracks

1.2 0.65 0.74 0.37

Rejection 39% 26% 29% 18%

Input Events 1159

Muon objects

4510 Pt>4 Eta matching

Pt>4 and eta matching

SVT confirmed

616 253 350 140

Events selected

237 131 166 85

Avg. #of SVT tracks

0.45 0.22 0.3 0.13

Rejection 20% 11% 14% 7%

Front

Rear

What’s next

•Introduce muons in pattern recognition•Understand matching efficiency•Understand tracking resolution•Further improvements:

•Stiffer Pt cut on muons•Appropriate range in eta/Pt for patterns•Narrower beam spot?