Download - A First DC2 Analysis with New Recons
Bill Atwood, SCIPP/UCSC, June, 2005 GLASTGLAST1
A First DC2 Analysis with New Recons
• DC1 Recap
• Recon Re-write Review– TkrRecon– CalRecon
• Good Energy Analysis
• PSF Analysis
THIS IS A PROGRESS
REPORT
ALL ANALYSIS ARE
PRELIMINARY
Bill Atwood, SCIPP/UCSC, June, 2005 GLASTGLAST2
DC1 RecapCuts: 1/1
Ratio 95/68 > 3Meets SREvents Eff.: 94.5%
Cuts: 3/2
Events Eff.: 52.3%
Cuts: 3/4
Events Eff.: 19.1%
Cuts: 2/1
An extensive analysis was performedto optimize PSF and energy resolutionwhile maintaining the maximum Aeff.
This was the first complete analysisdone using the Geant 4 Simulation(previous Glast Analysis used the Gismo simulation)
Bad-Cal = 4.5%
Eff. = 82%
Bill Atwood, SCIPP/UCSC, June, 2005 GLASTGLAST3
Background Rejection in DC1
3 Classes of Background after selectionfor good energy and directionreconstruction
Upward moving events
Earth Limb events
Downward moving events
Prob. > .5
Prob. > .9
A Classification Tree analysis was constructed allowing cutting on the probability that an event was a (vs. Background)
However – to meet the Science Req. for Backgroundcontamination – the remaining Aeff was lower then the goal (it did meet the Sci. Req.)
Bill Atwood, SCIPP/UCSC, June, 2005 GLASTGLAST4
Conclusions from DC1
The Status of the Reconstruction in GLAST was marginal
1) The code had been patch, re-patched, etc. many times
2) The code had become needlessly complex and essentially un-maintainable3) The algorithms (particularly for the Calorimeter) were undeveloped
Major Effort was Launched to completely re-write the Tracker and Calorimeter Recon
1) Emphasis on uniformity and simplicity2) Migrate related task to one area3) Re-vamp and re-assess poorly functioning algorithms (esp. Vertexing and Calorimeter)
Bill Atwood, SCIPP/UCSC, June, 2005 GLASTGLAST5
TDS Classes Condensed and Simplified:
– TkrTrackParams– TkrTrackHit– TkrTrack
Tracker Recon Re-write
Control Name Internal Variable
Def. Value
Description
MinEnergy m_minEnergy 30. Min. energy to use for setting search regions
SigmaCut m_sigmaCut 9.0 Sigma cut for picking up points
FirstTrkEnergyFrac
m_1stTkrEFrac .8 First track energy fraction
MinTermHitCount m_termHitCnt 16 Min. no. of hits on best track to terminate search
MaxNoCandidates m_maxCandidates
10 Max. allowed number of candidate tracks
MaxChisq m_maxChiSqCut 40. Max allow Combo Pat. Rec. Chisq. (1st fit)
NumSharedFirstClusters
m_hitShares 6 Number of first clusters which can be shared
MaxNumberTrials m_maxTrials 50 Max. number of trial candidates to test
FoVLimit m_PatRecFoV .19 Minimum cos(theta) for track trials
MinCosKink m_minCosKink .7 Minimum cos(theta) for a track kink
MaxTripletRes m_maxTripRes 30. Max. un-normalized residual for first 3 TkrPoints
External Controls
Program architecture simplified
– TkrFitHit– TkrFitMatrix– TkrFitPar– TkrFitPlane– TkrFitTrackBase– TkrKalFitTrackBa
se– TkrKalFitTrack– TkrPatCand– TkrPatCandHit– TkrRecInfo– TkrTrackTab
Bill Atwood, SCIPP/UCSC, June, 2005 GLASTGLAST6
SUPPORT PANEL
SSD PLANE
W RADIATORPut Vertexat Radiator Mid-Point
FoundTracks
SUPPORT PANEL
SSD PLANE
W RADIATOR
Put VertexDOCA Point
FoundTracks
All Other CasePut Vertex at Z locationof start of the 1st Track
Preferred SolutionIf 2 Tracks share the same first hit
Next Best SolutionIf DOCA location of 2 tracks lies before 1st Hit
New Vertex Algorithm
Vertex Location Combining TracksMultivariate Averaging: 1
21
1
21
211
1
CC
PCPCPPair
)()( 21
211
111
21
1 PCPCCCPPair
where Pi are the parameter vectors of the combination (Pair) and tracks (P1 and P2) and Ci are the covariance matrices
where
112
11 )( CCCPair
)()()()( 21
2Re211
1Re12
PairsT
PairPairsT
Pair PPCPPPPCPP
Pairs CCC 2,12,1Re
The parameter vectors are (x, Sx, y, Sy)
Bill Atwood, SCIPP/UCSC, June, 2005 GLASTGLAST7
1) Put GLAST’s Fracture Energy Back Together
1 GeV Thin Radiator Hits
Thick Radiator HitsBlank Radiator Hits
Calorimeter Xtals
Gap Between Tracker Towers
Gap Between CAL. Towers
Leakage out CAL. Back
CalRecon Re-write
2) Better Background Rejection Cuts Shower Shape parameters3) Move code to where it belongs! AnalysisNtuple CalRecon
Bill Atwood, SCIPP/UCSC, June, 2005 GLASTGLAST8
CalRecon Re-write (cont.)
LSQ Fit to Layers Moments
)ˆˆ(cosCalDirErr 1CalMC tt
A Major Change: Replace Layer-by-Layer Analysis with Energy-Moments
Energy Moments: Same as Classical Mech. Mass moments with energy replacing mass (see Goldstein) (first used by S. Ritz in GLAST)
Long. Moment Trans. Moment
Bill Atwood, SCIPP/UCSC, June, 2005 GLASTGLAST9
Good Energy Analysis
But First: The New Data Sets - Major effort by many people - Took a couple of shots to get right - 1.5x106 All Gamma* run 23-June-2005
- 6 x106 Orbit-Average Background run 24-June-2005
- All data run on SLAC Batch Farm available at GLAST ftp site
- These are the first large data sets using new Recons
Pruning Selections: 1) TkrNumTracks > 0 standard mode 2) TkrNumTracks = 0 Cal-Only Events!
Initial Cuts: 1) CalEnergyRaw > 5 MeV and CalCsIRLn > 4 rad. len.2) Tkr1ZDir < -.2 (FoV)
color range: 0 - 150
*All Gamma: 2 str. , 18 MeV – 180 GeV, 1/E Spectrum
Bill Atwood, SCIPP/UCSC, June, 2005 GLASTGLAST10
Energy Assessment
EvtDeltaEoE = E
E
Top plots show dep. on MC parameters
Bottom plots show dep. on Recon parameters
was EvtMcEnergySigma
Bill Atwood, SCIPP/UCSC, June, 2005 GLASTGLAST11
Good Energy CT AnalysisData divide into Energy Ranges using CalEnergyRaw
CalEnergyRaw < 350 MeV 350 - 3500 MeV CalEnergyRaw > 3500 MeV
MedCalLowCal HiCal
Bill Atwood, SCIPP/UCSC, June, 2005 GLASTGLAST12
Energy CT Details1) Produce a set of variables that are ~independent of cos() and E Parametric function of Tkr1ZDir and EvtLogEnergy
2) Define Class "GoodEnergy" & "BadEnergy" GoodEnergy: (will explore dependence on this)
2) Derive a CT for each of the EvtEnergyRaw Bins
35.E
E
Low CAL
Bill Atwood, SCIPP/UCSC, June, 2005 GLASTGLAST13
more Energy CT Details
Med CAL
High CAL
Bill Atwood, SCIPP/UCSC, June, 2005 GLASTGLAST14
Energy CT Dependencies
20.E
E30.
E
E 35.E
E
Since the energy resolution is improved – try more restrictive definition of "Good Energy"
100
80
60
20
40
0
100
80
60
20
40
0
100
80
60
20
40
0
Eff.
NOISE DC1 ChoiceSelect this one
Anomaly Use of Tkr1TotTrAve in Cal Low CT
This is part of a problem atHigh Energies .... more later
Expected Behavior
What's happening here?
Bill Atwood, SCIPP/UCSC, June, 2005 GLASTGLAST15
Integrated Over FoV On Axis
DC1 Resolution
DC2 Resolution
DC1 Resolution
DC2 Resolution
Preliminary DC2 Energy Resolution
Aeff x = 2.76 m2-strAeff x = 4.02 m2-str
High EnergyDeficit causedby Pat. Rec.Confusion!
Bill Atwood, SCIPP/UCSC, June, 2005 GLASTGLAST16
Root Cause of Hi E Deficit
Event #6 Bad Cal Dir
Missed Track
Event #9 Bad Cal Dir
Missed Track
Event #6 Bad Cal DirIncoming
Incoming
Pictures and Words....
These events come from Old CalReconbut effect remains.
First attempt to fix problem: USE CAL DIRECTION
100 GeV
100 GeV
Clearly there's more work to do here!
Bill Atwood, SCIPP/UCSC, June, 2005 GLASTGLAST17
A First PSF Analysis for DC2Strategy: Divide and Conquer!
1) Split Events in Thin and Thick Conversion locations2) For Events with > 1 Tkr. Vertices decide whether or not to use vertexed solution
Example: Thin Radiator – Vertex CT
Bill Atwood, SCIPP/UCSC, June, 2005 GLASTGLAST18
More PSF CT Details
Strategy: Divide and Conquer!
3) Find and tag (a la probability) Events with large PSFs
4) Finally – add a knob to describe quality of reconstruction - Using a REGRESSION TREE
Bill Atwood, SCIPP/UCSC, June, 2005 GLASTGLAST19
Sel. 1 Sel. 2 Sel. 3 Sel. 4 Sel. 1 Sel. 2 Sel. 3 Sel. 4
PSF68(100MeV) 4.7 4.1 3.6 3.0 4.2 3.8 3.3 2.6
PSF95/PSF68 4.4 3.0 2.3 2.2 3.2 3.0 2.6 2.3
Rel. Eff. (%) 100 94.5 52.3 19.1 100 95.2 74.0 46.2
DC1 DC2
Integrated over FoV On Axis
Preliminary DC2 PSFs
Bill Atwood, SCIPP/UCSC, June, 2005 GLASTGLAST20
DC2 Background RejectionNothing has been done with the recently run data. (only became available late last Friday)
But – Here's is a peek – Preemptory cuts: 1) GoodEnergy.Prob > .25 2) AcdDOCA > 250 3) Only Thin Radiator Events Analyzed so far
XtalsNo
EXtalsNoioCalXtalRat TOTAL
.
01..
Data: 5.1x106 Orbit Ave. Bkg. .75x106 All Gamma
942 Events (Good News)15642 Events
Bill Atwood, SCIPP/UCSC, June, 2005 GLASTGLAST21
more DC2 Background Rejection
TOTAL
Energy
E
ExpectedMIPoCalMIPRati
EnergySingleXtalMaxEneCalXtalMax .
Bill Atwood, SCIPP/UCSC, June, 2005 GLASTGLAST22
more DC2 Background Rejection
nsRmsEvtECalTra Energy & Angle Compensate CalTransRms
Note: In AnalysisNtuple all variables beginning with EvtE..... are previously defined variables which have been compensated for log(E) and cos() dependencies.
Bill Atwood, SCIPP/UCSC, June, 2005 GLASTGLAST23
Conclusions
The 1st DC2 Workshop has already accomplished 90+% its goals! - look at all the work it stimulated!
The Recon re-writes show good improvements in - Energy Reconstruction- PSF - New Variables to Reject Background
The (first) large data samples are providing the next level of insight in the Recons
- TkrRecon need more work in the area of very High Energy reconstructions - CalRecon needs MIP finding and more work to refine moments analysis (emphasis on directions)