KalFitAlg: recent
developments
and tests
WANG Dayong
Jan.18,2006
Outline
Recent developments and some tests
Status and usage
Present performances
Existing problems and possible solutions
The next to do
A retrospect: what we achieved for
Boss5.0.0(Nov,2005)
 Event model in both TDS and DST are fixed, root file
persistified, the loop closed for KalTrack
 Previous memory leakage problem extensively
inspected and cured by a new model with improved
track-hit relation after discussion
 Check and use nearly the same material and geometry
parameters with simulation
 Run smoothly with both Pattern Recognition algs and
nearly the same or a little better helix parameters and
momentum as PR algs obtained, the tendency of error
matrix variation is correct with 5 particle hypotheses.
0.4GeV/c Proton, theta=90degree
Mean
-0.002364
Sigma 0.01272
Mean
-0.002364
Sigma 0.01272
Recent developments since Dec
 Backward fitting with different mass hypotheses
 Flight length and TOF calculation
 Sampling length calculation
 Extraction of control flags and parameters
 Codes adjustment and comment to make it more clear a
 Many checks and tests for multiple scattering, energy
loss treatment, inner wall treatment, choices for cuts,
etc (see the following)
Tests and debug
With and without material effect
Different LR decision
All hits or used hits
Drift distance and tof correction
Comparison of different mass hypotheses
Comparison of different matrix initialization
Different cuts for Δχ2
Status and usage
 Helix and error matrix at IP: 5 particle hyp. directly
for physics analysis
 Helix and error matrix at MDC innermost layer: 5
particle hyp. for 2nd vertex fitting
 Helix and error matrix at MDC outermost layer: 5
particle hyp. (optional), for track extrapolation
 Flight length from IP to outermost layer and time of
flight: different particle hyp. optional, for TOF recon.
 Sampling length at each layer: for dE/dx recon
Control flags and parameters
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



muls: multiple scattering 0:close 1: open
loss: energy loss 0:close 1:open
lr : how to set lr ambig 0:independendtly 1:use lr from PR
matrixg: the factor to use in matrix initialization
debug: debug verbose 0:close 1--4: lower to maximum
ntuple: control of ntuple using bitmap FEDCBA
A:n101 B:n103 C:n102/n104 D:n105 E:mctruth in n101 F:error matrix









activeonly: whether use active hits only 0:all 1:active hits only
matfile, cylfile: dir and name of data file currently used
deltachi2_cutf , deltachi2_cutfs: Δχ2 cuts
pe_cut , pmu_cut , ppi_cut , pk_cut , pp_cut: mom cut in filter
back :backward fitting 0:close 1:open
i_back: mass hyp. used in backward fitting <0 :only pion
Pt: pt cut for backward fitting
tofflag : re-calculate the drift distance with tof correction
tof_hyp: mass hypothesis when calculate TOF
Choice of cuts for Δχ2
One cut is not good enough, so we set two,
different for forward and backward fitting
The criteria is the distribution of chisq and
probability
The cut is tested with kk2f, dimu, and
different tester samples
At present, the cut is set as 7.0 and 9.0
respectively, still need optimization
1GeV/c Pion Δχ2=7,9
e
K
mu
p
pi
trk
e
mu
pi
K
p
length
tof
Psi’’ inclusive Δχ2=7,9
e
K
mu
p
pi
trk
e
mu
pi
K
p
length
tof
Two track resolution(1)
Two track resolution(2)
Two track resolution(3)
Helix parameters:1GeV pion
Helix parameters:1GeV pion
Helix parameters:1GeV pion
Helix parameters:1GeV pion
Helix parameters:1GeV pion
Helix parameters:1GeV pion
Helix parameters:1GeV pion
Helix parameters:0.5GeV proton
Helix parameters:0.5GeV proton
J/Psirho pi
To test the error matrix with the help of
kinematic fit
The algorithm is provided by Kanglin He
4C efficiency is lower, so some problem must
exist
Careful check and test is still going on
J/Psirho pi :test
event
2 good trks
2 pion
>=2 photon
VtxFit
4C Fit
5C Fit
MdcTrkR
econ
1000
459
375
351
350
319
315
After
KalFit
1000
459
375
351
350
223
222
TrkReco
1000
663
618
564
562
483
475
After
KalFit
1000
663
618
564
563
315
309
J/Psirho pi :test
Matrix
gain=1
Matrix
Diag
gain4000 Matrix
without No mat
NUMF effect
VtxFit
4C Fit
5C Fit
350
226
224
349
223
222
350
216
215
350
223
222
Inverse
lay dire
Inverse Inverse
wir direc bck-fwd
VtxFit
4C Fit
5C Fit
without
wall
350
219
218
350
218
218
350
213
212
350
221
219
349
212
212
Inverse
lr defin
350
216
215
Possiblities
• Multiple hits in a single layer
• Sign conventions
• Others???
Other issues
Non Uniform Magnetic Field:
Wire sagita: the framework for this is there;
c++ implementation of the correction
function by Jike Wang
Wire shift, x-t relation, wire resolution:
from calibration
The next to do
Find out the origin of the problem rho pi
and improve
Optimization of all the parameters and cuts
with different physics events
More error matrix check with other physics
channels
Documentation and notes