Status of Fast Tracking Algorithm MdcHough

Guowei YU

8th March 2006

Outline

Introduction

MdcHough Algorithm

Results and Discussions

Summary

Introduction Algorithm Developments in MDC Reconstruction

Presented by W.D.Li ,Migrated from ATLAS

Developer Offline Algorithm Events filter

AlgorithmS.L.Zang Mdc Tracking

Y.Zhang MdcPatRec

X.M.Zhang MdcFastTrk

G.W.YU MdcHough

Purpose Efficient track finding Nice transverse momentum resolution High efficiency of track finding at high noise level

MdcHough Algorithm

43 layers,19 axial type|cos|<0.93Cell is near square ~8.1mm

Interaction point

Cosθ=0.83

Cosθ=0.93

Flow of MdcHough

Hits PT

Initial track finding

Local maximum finding

Track selection and Merging

Track fitting

MdcHough

Initial track finding (use a LUT-base Hough Transform) (R,) (,1/pT) [(0~2) pT (400MeV~)]

qCTR=sin (–0) CT= 0.3/pT

Build a wire-ordered look-up table ( 1/pT= 300 100)

.

wire n+1

wire n

active wire n-1

wire .

.

. .

Bin 1 Bin 2 … Bin 100

Bin 1 Bin 2 … Bin 100

Bin 1 Bin 2 … Bin 100

.

wire-ordered

LUT

Flow of MdcHough

Local maximum finding (select good track candidates by wired-oreded LUT)

Track selection and Merging Nhit > 15 Merge some tracks sharing more th

an 9 hits

Flow of MdcHoughFlow of MdcHough

15 15 1616 18 1713 14 14

Track fitting Obtain hits from Bin-ordered LUT Fitting track to get PT by using lpav tool

.

bin n+1

bin n

bin bin n-1

number .

.

. .

wire 1 wire 2 … wire 19

wire 1 wire 2 … wire 19

wire 1 wire 2 … wire 19

.

bin-ordered

LUT

Flow of MdcHoughFlow of MdcHough

Results and Discussion Track Reconstruction CPU

Time ~ 1ms/1 track Resolution of PT(1.0GeV )

Generate (PT :1GeV) by Fixpt Efficiency of Reconstruction

() VS cos(polar angular)

p=8.0 MeV

Efficiency of Reconstruction VS PT( e p)

Momentum resolution VS PT (μ,e,π,p) Double Gauss Fit

Noise level type 0: = C type 1: 1/r type 2: 1/r2 (PT:1.0GeV )

Efficiency vs noise Resolution VS noise

Summary It costs about 1ms to reconstruct 1 track Efficiency of reconstruction() : >99% (PT>300MeV) for single track >99% when noise level are 5%,10% ,15% and 20% decrease quickly when polar angular more than 0.8 Resolution of momentum(p): PT < 1.0GeV p of proton is more than others

PT > 1.0GeV p keeps about same value for all particles p turns bad at noise level is more than 10% in type “0” Same results by adding wires shift; Further work is to enhance near polar angular and test the Algorithm

in adjusted magnetic field

Thank!