Status of Fast Tracking Algorithm Mdc Hough Guowei
- Slides: 14
Status of Fast Tracking Algorithm Mdc. Hough Guowei YU 8 th March 2006
Outline Introduction Mdc. Hough Algorithm Results and Discussions Summary
Introduction q Algorithm Developments in MDC Reconstruction Developer S. L. Zang Y. Zhang X. M. Zhang G. W. YU q Offline Algorithm Mdc Tracking Mdc. Pat. Rec Events filter Algorithm Mdc. Fast. Trk Mdc. Hough Presented by W. D. Li , Migrated from ATLAS
q Ø Ø Ø Purpose Efficient track finding Nice transverse momentum resolution High efficiency of track finding at high noise level
Mdc. Hough Algorithm Cosθ=0. 83 Cosθ=0. 93 Interaction point ü 43 layers, 19 axial type ü|cos |<0. 93 üCell is near square ~8. 1 mm
Flow of Mdc. Hough Initial track finding Mdc. Hough Local maximum finding Hits PT Track selection and Merging Track fitting
Flow of Mdc. Hough q Ø Ø Initial track finding (use a LUT-base Hough Transform) (R, ) ( , 1/p. T) [ (0~2 ) p. T (400 Me. V~ )] q. CTR=sin ( – 0) CT= 0. 3/p. T Build a wire-ordered look-up table ( 1/p. T= 300 100) . wire n+1 wire n active wire n-1 wire. . Bin 1 Bin 2 … Bin 100 . wire-ordered LUT
Flow of Mdc. Hough q Local maximum finding (select good track candidates by wiredoreded LUT) q Ø Ø Track selection and Merging Nhit > 15 Merge some tracks sharing more than 9 hits 15 15 16 16 18 17 13 14 14
Flow of Mdc. Hough q Ø Ø Track fitting Obtain hits from Bin-ordered LUT Fitting track to get PT by using lpav tool. . . bin n+1 bin n-1 number. . wire 1 wire 2 … wire 19 . bin-ordered LUT
Results and Discussion q q Track Reconstruction CPU Time ~ 1 ms/1 track Resolution of PT(1. 0 Ge. V ) p=8. 0 Me. V q q Generate (PT : 1 Ge. V) by Fixpt Efficiency of Reconstruction ( ) VS cos (polar angular)
q Efficiency of Reconstruction VS PT( e p) q Momentum resolution VS PT (μ, e, π, p) Double Gauss Fit
Noise level type 0: = C type 1: q Efficiency vs noise 1/r type 2: 1/r 2 (PT: 1. 0 Ge. V ) q Resolution VS noise
Summary ü It costs about 1 ms to reconstruct 1 track ü Efficiency of reconstruction( ) : v >99% (PT>300 Me. V) for single track v >99% when noise level are 5%, 10% , 15% and 20% v decrease quickly when polar angular more than 0. 8 ü Resolution of momentum( p): v PT < 1. 0 Ge. V p of proton is more than others v PT > 1. 0 Ge. V p keeps about same value for all particles v p turns bad at noise level is more than 10% in type “ 0” ü Same results by adding wires shift; Ø Further work is to enhance near polar angular and test the Algorithm in adjusted magnetic field
Thank !
