1. More on making fake TT clusters More creating Fake TT clusters We can compute the number of combinations instead of the purity (following all the possible candidates from TT1 to TT2) (this slides) We can “update” the state using a “helix” model instead of a “straight line” model, and the window in X2 will be reduced. Use: DaVinci v6r0 field 044 (week one) Summary: [For L1] if we want to improve the momentum resolution (and reboustness) we can: increase the B strength (Bdl 2xf043) improve TT slope resolution (high energy) large lever arm smaller pitch What is the effect of the stereo angles of TT? 1. The opening window changes with the angles but there is no favoured angle that increases the total purity Jose A. Hernando, 14/04/02, weekly trigger meeting

2. More making fake TT clusters :: method & configurations Number of states Propagate from Velo to TT open window at TT1/X1 to collect All hits for p > 2 GeV X window = 8 mm Y window = 4 mm creates straight line states for each hit on TT1/X1 propatate to TT1/V1 and open window to collect all hits U window = 0.5 mm create and update states the same propagate to TT2/x2 Open window (x=1.8, y=0.8) and create/update states Propagate to TT2/u2... 2 Station Configurations Current design: one TT plane measures X other TT plane rotated (+,-) phi Cross design: one TT plane rotated - phi other TT plane rotated +phi One TT station

3. More on making fake TT clusters :: states vs phi, current desing Current design valley between 3-10 deg minima 4 deg at larger angles, the open window increases for the 2nd plane at larger angles we start to not resolve ghost hits 1/MeV

4. More on making fake TT clusters :: states vs phi, cross desing Cross design valley between 2-10 deg minima 4 deg at larger angles, the open window for the 1st plane decreases (less states) at larger angle the window on the 2nd plane increases at larger angles we start to not resolve ghost hits

5. More on making fake TT clusters :: zoom Cross design Current design

6. More on making fake TT clusters :: an explanation Angle of the TT station system? A larger angle => better Y segmentation A larger angle at a certain value, can not resolve ghost. as the window increases with angle, most probability of accenting hits Angle of the system Tan (phi) = pitch/Y, d/Y Pith=0.2 Y = 4 mm Phi= 3.- 6 deg. (0.2, 0.4) Ghost hit outside allowed window (8,4) mm window Limitation by MS and P-min

7. More on making fake TT clusters :: conclusions and more Counting the number of states for different angles there is a minima region between 3-10 deg, soft best arount 4 deg. the stereo angle determined by the pitch/open window on Y (0.2,0.4/4) [3,6] deg We are in a good place! More...: We can “update” the state using a “helix” model instead of a “straight line” model, and the window in X2 will be reduced. Corolary: we get almost at the same time a method for Velo-TT pattern recognition and p measurement! (similar to using the filter of the Kalman Filter) [On hold, for the moment] I started to look into: Teubert’s idea: confirming the L1 decision and [a brigde towards O. Callot´s HLT] selecting the velo tracks to do “full” reconstruction (create a 2nd vertex & mass window) About the Notes: If we desmotrate a better slope resolution on TT helps the Pt mistakes for L1, at hight energies?, should we then make one note with B field for L1 & TT revisited?.