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


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%


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.)


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)


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


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)


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


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


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


Energy Assessment

EvtDeltaEoE = E

E

Top plots show dep. on MC parameters

Bottom plots show dep. on Recon parameters

was EvtMcEnergySigma


Good Energy CT AnalysisData divide into Energy Ranges using CalEnergyRaw

CalEnergyRaw < 350 MeV 350 - 3500 MeV CalEnergyRaw > 3500 MeV

MedCalLowCal HiCal


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


more Energy CT Details

Med CAL

High CAL


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?


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!


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!


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


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


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


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


more DC2 Background Rejection

TOTAL

Energy

E

ExpectedMIPoCalMIPRati

EnergySingleXtalMaxEneCalXtalMax .


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.


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)

a first dc2 analysis with new recons

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