Transcript ppt
A First DC2 Analysis with New Recons • DC1 Recap • Recon Re-write Review – TkrRecon – CalRecon • Good Energy Analysis • PSF Analysis Bill Atwood, SCIPP/UCSC, June, 2005 1 GLAST DC1 Recap Cuts: 1/1 An extensive analysis was performed to optimize PSF and energy resolution while maintaining the maximum Aeff. This was the first complete analysis done using the Geant 4 Simulation (previous Glast Analysis used the Gismo simulation) Ratio 95/68 > 3 Cuts: 2/1 Meets SR Events Eff.: 94.5% Cuts: 3/2 Cuts: 3/4 Events Eff.: 52.3% Events Eff.: 19.1% Eff. = 82% Bad-Cal = 4.5% Bill Atwood, SCIPP/UCSC, June, 2005 2 GLAST Background Rejection in DC1 3 Classes of Background after selection for good energy and direction reconstruction Prob. g > .5 Upward moving events Earth Limb events Downward moving events Prob. g > .9 A Classification Tree analysis was constructed allowing cutting on the probability that an event was a g (vs. Background) However – to meet the Science Req. for Background contamination – the remaining Aeff was lower then the goal (it did meet the Sci. Req.) Bill Atwood, SCIPP/UCSC, June, 2005 3 GLAST 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-maintainable 3) 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 simplicity 2) Migrate related task to one area 3) Re-vamp and re-assess poorly functioning algorithms (esp. Vertexing and Calorimeter) Bill Atwood, SCIPP/UCSC, June, 2005 4 GLAST Tracker Recon Re-write TDS Classes Condensed and Simplified: – – – – – – – – – – – TkrFitHit TkrFitMatrix TkrFitPar TkrFitPlane TkrFitTrackBase TkrKalFitTrackBa se TkrKalFitTrack TkrPatCand TkrPatCandHit TkrRecInfo TkrTrackTab – TkrTrackParams – TkrTrackHit – TkrTrack Program architecture simplified Bill Atwood, SCIPP/UCSC, June, 2005 5 External Controls 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 FirstTrkEnergyFr ac m_1stTkrEFrac .8 First track energy fraction MinTermHitCount m_termHitCnt 16 Min. no. of hits on best track to terminate search MaxNoCandidates m_maxCandidate s 10 Max. allowed number of candidate tracks MaxChisq m_maxChiSqCut 40. Max allow Combo Pat. Rec. Chisq. (1st fit) NumSharedFirstCl usters 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 GLAST New Vertex Algorithm Vertex Location Put Vertex at Radiator Mid-Point Combining Tracks Preferred Solution W RADIATOR If 2 Tracks share the same first hit SSD PLANE SUPPORT PANEL Found Tracks Next Best Solution All Other Case Put Vertex at Z location of start of the 1st Track Bill Atwood, SCIPP/UCSC, June, 2005 PPair (C11 C 21 )1 (C11 P1 C 21 P2 ) C Pair (C11 C 21 )1 Put Vertex SUPPORT PANEL DOCA Point If DOCA location of 2 tracks lies before 1st Hit Multivariate Averaging: PPair C11 P1 C 21 P2 C11 C 21 W RADIATOR SSD PLANE where Pi are the parameter vectors of the combination (Pair) and tracks (P1 and P2) and Ci are the covariance matrices 1 T 1 2 ( P1 PPair )T C Re s 1 ( P1 PPair ) ( P2 PPair ) C Re s 2 ( P2 PPair ) where C Re s1, 2 C1, 2 C Pair Found Tracks The parameter vectors are (x, Sx, y, Sy) 6 GLAST CalRecon Re-write 1) Put GLAST’s Fracture Energy Back Together 1 GeV g Thin Radiator Hits Gap Between Tracker Towers Thick Radiator Hits Blank Radiator Hits Gap Between CAL. Towers Calorimeter Xtals 2) Better Background Rejection Cuts Shower Shape parameters 3) Move code to where it belongs! AnalysisNtuple CalRecon Bill Atwood, SCIPP/UCSC, June, 2005 7 Leakage out CAL. Back GLAST CalRecon Re-write (cont.) 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 Moments LSQ Fit to Layers CalDirErr cos 1 ( tˆMC tˆCal ) Bill Atwood, SCIPP/UCSC, June, 2005 Trans. Moment 8 GLAST 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* - 6 run 23-June-2005 x106 Orbit-Average Background Initial Cuts: 1) CalEnergyRaw > 5 MeV and CalCsIRLn > 4 rad. len. 2) Tkr1ZDir < -.2 (FoV) color range: 0 - 150 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! *All Gamma: 2p str. , 18 MeV – 180 GeV, 1/E Spectrum Bill Atwood, SCIPP/UCSC, June, 2005 9 GLAST Energy Assessment E EvtDeltaEoE = was EvtMcEnergySigma E Top plots show dep. on MC parameters Bottom plots show dep. on Recon parameters Bill Atwood, SCIPP/UCSC, June, 2005 10 GLAST Good Energy CT Analysis Data divide into Energy Ranges using CalEnergyRaw MedCal LowCal CalEnergyRaw < 350 MeV Bill Atwood, SCIPP/UCSC, June, 2005 350 - 3500 MeV 11 HiCal CalEnergyRaw > 3500 MeV GLAST Energy CT Details 1) Produce a set of variables that are ~independent of cos(q) and E Parametric function of Tkr1ZDir and EvtLogEnergy 2) Define Class "GoodEnergy" & "BadEnergy" GoodEnergy: E .35 (will explore dependence on this) E 2) Derive a CT for each of the EvtEnergyRaw Bins Low CAL Bill Atwood, SCIPP/UCSC, June, 2005 12 GLAST more Energy CT Details Med CAL High CAL Bill Atwood, SCIPP/UCSC, June, 2005 13 GLAST Energy CT Dependencies Since the energy resolution is improved – try more restrictive definition of "Good Energy" E .20 E Eff. E .30 E 100 80 100 80 60 60 40 40 20 20 0 0 NOISE Anomaly E .35 E 100 80 60 DC1 Choice Select this one 40 20 0 Expected Behavior This is part of a problem at High Energies .... more later Use of Tkr1TotTrAve in Cal Low CT What's happening here? Bill Atwood, SCIPP/UCSC, June, 2005 14 GLAST Preliminary DC2 Energy Resolution On Axis Integrated Over FoV DC1 Resolution DC1 Resolution DC2 Resolution DC2 Resolution High Energy Deficit caused by Pat. Rec. Confusion! Aeff x W = 4.02 m2-str Bill Atwood, SCIPP/UCSC, June, 2005 Aeff x W = 2.76 m2-str 15 GLAST Root Cause of Hi E Deficit Pictures and Words.... Incoming g Event #6 Bad Cal Dir 100 GeV g These events come from Old CalRecon but effect remains. First attempt to fix problem: USE CAL DIRECTION Event #9 Bad Cal Dir Incoming g 100 GeV g Missed Track Event #6 Bad Cal Dir Clearly there's more work to do here! Missed Track Bill Atwood, SCIPP/UCSC, June, 2005 16 GLAST A First PSF Analysis for DC2 Strategy: Divide and Conquer! 1) Split Events in Thin and Thick Conversion locations 2) 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 17 GLAST 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 18 GLAST Preliminary DC2 PSFs Integrated over FoV On Axis DC2 DC1 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 Bill Atwood, SCIPP/UCSC, June, 2005 19 GLAST DC2 Background Rejection Nothing has been done with the recently run data. (only became available late last Friday) But – Here's is a peek – Data: 5.1x106 Orbit Ave. Bkg. Preemptory cuts: .75x106 All Gamma 1) GoodEnergy.Prob > .25 2) AcdDOCA > 250 3) Only Thin Radiator Events Analyzed so far 15642 Events CalXtalRatio Bill Atwood, SCIPP/UCSC, June, 2005 20 942 Events (Good News) No. Xtals .01ETOTAL No. Xtals GLAST more DC2 Background Rejection CalXtalMaxEne Max . SingleXtalEnergy CalMIPRatio Bill Atwood, SCIPP/UCSC, June, 2005 21 MIPEnergy Expected ETOTAL GLAST more DC2 Background Rejection EvtECalTransRms 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(q) dependencies. Bill Atwood, SCIPP/UCSC, June, 2005 22 GLAST 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) Bill Atwood, SCIPP/UCSC, June, 2005 23 GLAST