Post on 23-Jan-2016
description
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!