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Analysis of Background Rejection Status for DC2 with Focus on GLAST-TS Production

This document presents a detailed analysis of the background rejection status for the DC2 dataset concerning GLAST-TS production. The study covers three main series of events, detailing the triggering rates, energies, and tracking conditions needed for effective background rejection. Key parameters such as active distances, energy thresholds, and efficiency calculations are discussed in the context of filtering and selecting relevant event data. The analysis highlights challenges with specific event subclasses and proposes metrics for improved performance in discriminating signal from background noise.

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Analysis of Background Rejection Status for DC2 with Focus on GLAST-TS Production

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  1. Back Ground Rejection Status for DC2 a la Ins. Miner Analysis

  2. First Look at glast-ts production 3-Oct-2005 Series 1: 409160 in tuple / 123556 after RF (only FilterStatus _HI == 0 used by TB) (This series does not have the single tile energy vars) after Act.Dist&SSDVeto: 82306 after GoodEnergyProb > .1: 81674 Series 2: 408151 in tuple / 123120 after RF after Act.Dist&SSDVeto: 82440 after GoodEnergyProb > .1: 81795 Series 3: 409098 in tuple / 123110 after RF after Act.Dist&SSDVeto: 82349 after GoodEnergyProb > .1: 81746 Each series equals .01 days or ~ 864 sec. on orbit with 744 per series live time due to the SAA – the 3 together represent 2232 sec. The following is from Toby's e-mail dated 4-Oct-05 5:33 pm Series incoming triggers downlink 1 38191926 6100518 409281 2 38053681 6078677 409415 3 38130276 6093686 409221 4 37845955 6054390 406189 total 152221838 24327271 1634106 Rates 8177 Hz 549 Hz Note: that the numbers I see are a little different in the incoming ntuples – Toby says this is due to him taking numbers from the logs rather then the tuples and failed jobs don't get counted properly. Total live time = 2976 sec. for the 4 series

  3. Vtx Topologies, THICK Radiators, CalEnergyRaw < 350 MeV (Note I'm trying breaking the lowest energy bin into THICK & THIN radiators at Steve's suggestion) Prefilter: Exclude AcdUpperTileCount > 0 | AcdLowerTileCount > 1 | AcdRibbonActDist > -1999 where UpperTileCount = Top + 0 + 1 + 2 and LowerTileCount = 3 1000 #AGs as indicated 1547 Bkg. Events By Varying the # of AGs used to train the CT, the relative efficiency of the selection of Bkg and AGs changes. These are for Prob(g) > .50 700 500 400 300 200 100 The nominal rate for Bkg. in each channel must be kept to < .03 Hz By changing the number of AGs - its equivalent (? similiar at least) to weighting the events – except for the statistical fluctuations.

  4. 300 AGs This is what the CT vars. and probs. look for 3 different mixes of AGs BestEnergy > 100 MeV 500 AGs BestEnergy > 100 MeV 1000 AGs BestEnergy > 100 MeV

  5. Try Training CTs using BestEnergy > 100 MeV PreFilter as before BestEnergy > 100 MeV This is marginally worse... so I will inculded all events to train CTs The event mix changes with cos(q) as well. We'll probably de-select on events near the edge of the FoV (e.g. cos(q) < -.3 rather going out to cos(q) < -.2) No cut case PreFilter cos(q) < -.3 as before AG eff = 129/235 = .54 Bkg. eff = 25/792 = .03 Prob. > .5 CT Variables and Prob for Vtx, Thick, < 350 MeV

  6. VTX, THIN, CalEnergyRaw < 350 MeV, cos(q) < -.3 This is much worse in terms of efficiencies – PreFilter THICK eAG: .87 eBkg: .46 THIN eAG: .73 eBkg: .63 as before PreFilter THIN eAG: .92 eBkg: .84 Still its bad - but???? This PreFilter is considerably worse for the THICK events then the one dev. for it. THICK and THIN seem to be just DIFFERENT AcdActiveDist > -199 | AcdRibbonActDist > -1000 THIN eAG: .67 eBkg: .02 Prob>.5 cos(q) < -.3 && BestEnergy > 100 MeV

  7. VTX, All Layers, 350 < CalEnergyRaw < 3500, cos(q) < -.3 PreFilter All Layers eAG: .97 eBkg: .55 This g ineff. is consistent with conversions in blanket and tiles AcdActiveDist > -199 & AcdRibbionActDist > -1990 All events now have BestEnergy > 100 and cos(q) < -.3

  8. VTX, All Layers, 3500 < CalEnergyRaw, cos(q) < -.3 The Remaining Bkg Event PreFilter e- (e- Splash) Event Well Reconstructed AcdActiveDist > -10 | CalTrackAngle > .5 | CalTrackDoca > 40 This is NUTS! The event clearly has to be pointing at an ACD Side tile and there is no SSD Veto. The Doca Calc. says the event had a track well within a tile – so why is the ActiveDistance set to its rogue value? This is a glast-ts generated event. Can Toby find it? (It comes from either series 2 or 3) We NEED a picture of it!

  9. Vtx Topology Summary (All numbers for BestEnergy > 100 MeV & BestZDir < -.3) Prob. > .50 PreFilters Background Rejection Path (BR.Path) not yet determined All Gamma Loss .013 .120 .465 (g/Bkg) Background Background Source Breakdown MIP Finder Failure HeavyIons have gone away

  10. 1Tkr, THICK layers, CalEnergyRaw < 350 MeV Desperation: This is the toughest subclass. In DC1 we had to through all these away. This is better but clearly not there yet. cos(q) < -.3 PreFilter AcdActiveDist > -199 | AcdRibbonActDist > -1999 | AcdDoca < 1999 | CalTrackDoca > 200 | EvtECalTransRms > 2.5 | CalMaxXtalRatio > .8 | Tkr1FirstChisq > 2.5 | Tkr1ToTTrAve > 2 Note that ~ 50% of the events are below BestEnergy < 100 MeV THIN eAG: .68 eBkg: .03 Prob>.5 cos(q) < -.3 && BestEnergy > 100 MeV

  11. 1Tkr, THIN layers, CalEnergyRaw < 350 MeV cos(q) < -.3 PreFilter Desperation: This is the 2nd toughest subclass. AcdActiveDist > -199 | AcdRibbonActDist > -1999 | CalTrackDoca > 200 | EvtECalTransRms < .8 Note that ~ 40% of the events are below BestEnergy < 100 MeV THIN eAG: .72 eBkg: .04 Prob>.5 cos(q) < -.3 && BestEnergy > 100 MeV

  12. 1Tkr, All layers, 350 MeV < CalEnergyRaw < 3500 MeV cos(q) < -.3 PreFilter AcdActiveDist > -199 | AcdRibbonActDist > -1900 | CalTrackDoca > 40 | CalTrackAngle > .5 | CalXtalRatio > .85 All Layers eAG: .73 eBkg: .04 Prob>.5 cos(q) < -.3 && BestEnergy > 100 MeV

  13. 1Tkr, All layers, CalEnergyRaw > 3500 MeV cos(q) < -.3 Re-Make of 1Tkr Cal_Hi PreFilter This PreFilter was not done properly first time around. Here's a re-do CalTrackDoca > 30 | CalTrackAngle > .3 Leaving out all ACD vars. in PreFilter All Layers eAG: .98 eBkg: .015 Prob>.5 Note however that the CTs insist on using the ACD. cos(q) < -.3 && BestEnergy > 100 MeV

  14. 2nd Time Around 1Tkr Topology Summary (All numbers for BestEnergy > 100 MeV & BestZDir < -.3) Prob. > .50 PreFilters Background Rejection Path (BR.Path) not yet determined All Gamma Loss .075 .394 .641 (g/Bkg) Background Note how much larger the Bkgs are w.r.t. Vtx except for CalEnergyRaw > 3500 MeV Background Source Breakdown MIP Finder Failure

  15. v7r2 SLAC 2M All Gamma Run Pr(GAM) > .50 Number > 1 GeV = 1726 in 28 bins 62/bin x 50 bins = 3100 3100/(2x106 / 100) x 6 m2 <NBIN> * 150 = Aeff (cm2) or N>1GeV * 5.36 = Aeff(cm2) Aeff = 9300 cm2 2469/bin SRD Limit Number > 1 GeV = 70883 in 28 bins (2531) x 50 Bins = 113500 113500/2x106 x 37.7 m2-str <NBIN> * .943x10-3 = Aeff x DW(m2-str) or N>1GeV *3.37x10-5 =Aeff x DW(m2-str) Aeff x DW = 2.39m2-str Fall-off past 10 GeV improved – however this results from the CTs using AcdActiveDist to kill the high energy cosmic electron component in the background – it may be a fact of life for now... Background: 319 Events or .16 Hz (SRD ~ .03 Hz)

  16. cos(q) < -.9 Near On-Axis These basically meet the SRD cos(q) > -.6 Edge of FoV

  17. Direction Anti-Correlated events: 416 Events Residual Background Dissection PSF Class Prob.GAM > .3 (relaxed cut) 1151 Events These are dominated by upward moving protons. This is what the MIP Finder was suppose to identify No Correlation: 560 Events – large component of Limb gs PSF Class Direction Correlated events: 175 Events PSF Class Location of First Hit on Found Track Come in through the corners and there is a definite handedness this suggest a ERROR IN THE ACD CODE / GEOMETRY

  18. Event Spectra both MC Truth and as Reconstructed After PreFilter Stage No Prob.GAM Cut 61 Events Rate = .03 Hz Prob.GAM > .7 (Meets Aeff and Background rate req.) 62352 events > 1 GeV Aeff x DW = 2.1 m2-str

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