More technical description: http://www.pi.infn.it/~orso/ftk/ Introduction to FTK More technical description: http://www.pi.infn.it/~orso/ftk/ March 9, 2005 Introduction to FTK - M. Shochet

Introduction to FTK - M. Shochet What is the problem? In hadron colliders, the “easy” triggers are e, , , & generic jets. Is that good enough at the LHC? Opening a new energy frontier. SM  new physics, but what it is we don’t know  don’t ignore 3rd generation partons (b, ) ex: EWK symmetry breaking couples  mass  3rd generation important ex: March 9, 2005 Introduction to FTK - M. Shochet

Why is it hard to trigger on the 3rd generation? b : jet Generic jets have production cross  : narrow jet sections orders of magnitude larger. To identify b-jets and -jets, need tracks. b-jet: secondary vertex -jet: ≤ 3 tracks in narrow cone; no tracks around it 40 MHz interaction rate & 1 KHz level-2 accept rate  selection of b-jets and -jets must be done quickly! deadtime = L1 rate  L2 reject time As high as possible to lower PT threshold.  make as short as possible March 9, 2005 Introduction to FTK - M. Shochet

Existing ATLAS (& CMS) Trigger Track pattern recognition & fitting done in Intel PC’s. 20-50 msec because of overhead of getting all of the raw silicon hits into the processor and sorted for track finding. TOO LONG! March 9, 2005 Introduction to FTK - M. Shochet

Introduction to FTK - M. Shochet FTK (Fast TracKer) Based on the CDF SVT Finds and reconstructs with near offline d0 precision all tracks of PT > 1.5 GeV/c in ~20 sec. sample for Bs mixing Z → bb March 9, 2005 Introduction to FTK - M. Shochet

(prototype: SVT upgrade) How does it work? Complete pattern recognition on the fly as the silicon data passes by using pre-stored bank of possible hit patterns. CDF: 32K patterns/phi sector → 15M in ATLAS made possible by advances in -electronics in past decade (prototype: SVT upgrade) The Pattern Bank March 9, 2005 Introduction to FTK - M. Shochet

Pattern recognition in action March 9, 2005 Introduction to FTK - M. Shochet

Introduction to FTK - M. Shochet Track Fitting Very fast: In CDF, 200 nsec/track using FPGA. Narrow roads  linearized fit works well Linear equations (a few hardware adds and multiplies) with pre-stored coefficients: curvature, d0, , 2. Track impact parameter  = 48m March 9, 2005 Introduction to FTK - M. Shochet

Where does it fit in ATLAS? on L1 accept RODs SCT  Pixels  FTK “Level 1.5” ROBs ROBs silicon hits silicon tracks ask for ROI’s Level 2 March 9, 2005 Introduction to FTK - M. Shochet

First Step: Making the Physics Case ATLAS wants a few specific channels studied so the physics reach with and without FTK can be compared. In discussion with the ATLAS Physics Coordinators and others, we came up with a “short list”. March 9, 2005 Introduction to FTK - M. Shochet

Introduction to FTK - M. Shochet for measuring the b-jet response and resolution (-jet & Z-jet balance have theory/exp problems) for Mtop , MHiggs , … Problem: L1 trigger rate  higher jet ET threshold high threshold  high MJJ turn-on Solution: high PT Z’s 3-jet trigger highest ET jet is not tagged bb opening angle not fixed near 1800  lower MJJ threshold March 9, 2005 Introduction to FTK - M. Shochet

Introduction to FTK - M. Shochet Higgs Physics How much lower in tan can be reached? These jet PT’s are too low for existing triggers. How much does FTK help? March 9, 2005 Introduction to FTK - M. Shochet

Introduction to FTK - M. Shochet  leptons Need lower threshold for all  triggers. How low can the threshold be? (Fabiola) for the high PT response of TileCal across the detector Existing thresholds (35/45 GeV) too high for W’s (More general: isolated track triggers for calorimeter calibration – rapid level-2 rejection  higher level-1 rate) (Ian) Existing  trigger is for 1-prong only. Polarization information requires seeing other  decay modes. March 9, 2005 Introduction to FTK - M. Shochet

Introduction to FTK - M. Shochet More (Michelangelo) B physics (if initial  is very low) ex, March 9, 2005 Introduction to FTK - M. Shochet

Introduction to FTK - M. Shochet What has to be done? What drives trigger decisions is background rejection, not signal efficiency. For signal, a few thousand events probably are enough. But background studies require LOTS of events. At 10 minutes/simulated event, … Use fully simulated events to parameterize jet response (with fluctuations) jet trigger efficiency vs ET ( especially at level 1) Erik Brubaker is working on this. Use full simulation to parameterize FTK tracking: Pisa will get the FTKsim tools working with current ATLAS software then: tracking efficiency in jets, fake rate Then can do convincing physics studies with fast simulation. HOW?? (Iacopo) March 9, 2005 Introduction to FTK - M. Shochet