DC2 prep meeting June 27 2005 F.Longo et al. 1

GLAST LAT Bkg Rejection Italy

Background Rejection Activities Background Rejection Activities in Italyin Italy

Francesco LongoUniversity and INFN, Trieste, Italyfrancesco.longo@ts.infn.it

On behalf of the “North-East” INFN group thanks in particular to R.Rando, O.Tibolla, Y.Lei, G.Busetto and P.Azzi (University and INFN Padova)

Gamma-ray Large Gamma-ray Large Area Space Area Space TelescopeTelescope

DC2 prep meeting June 27 2005 F.Longo et al. 2

GLAST LAT Bkg Rejection Italy

Bkg Rejection activityBkg Rejection activity

• Starting from “simple cuts”• Collection of Bkg Rejection documentation • Understanding IM cuts (DC1 variables and cuts)• Classification Trees in R • New recent developments• Ready for new data• More Info: http://sirad.pd.infn.it/glast/ground_sw/dc2.html

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GLAST LAT Bkg Rejection Italy

““By hands” cutsBy hands” cuts

• First iteration using already suggested cuts • Look into Merit Tuple to find efficiency of rejection and gamma

acceptance• Reference docs (Atwood):

– “Instrument response studies” – “Post rome background rejection”

• Datasets:– DC1 prep background ntuples – DC1 prep gamma Merit nutple

• Divide events in particle type: gamma(signal), gamma(bkg), electron+positron, protons

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GLAST LAT Bkg Rejection Italy

Calorimeter categoriesCalorimeter categories

• Definitions: – No cal: CalEnergySum<5. || CalTotRLn≤2

– Low Cal: CalEnergySum>5. && CalTotRLn>2

– Med Cal: CalEnergySum>350. && CalTotRLn>2

– High Cal: CalEnergySum<3500. && CalTotRLn>2

– “Good Energy” events: “good_energy” = (EvtEnergySumOpt-MCEnergy)/MCEnergy

|”good_energy”| ≤ 35%

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GLAST LAT Bkg Rejection Italy

Signal events splitSignal events split

ALL Total No Low Med High

all 722594314226

(43.4%)

122081

(17%)

114224

(15.8%)

172063

(23.8%)

good81139

(66.4%)

94869

(83%)

142082

(83%)

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GLAST LAT Bkg Rejection Italy

Background events splitBackground events split

ALL Total No Low Med High

e 746232649293

(87%)

93933

(13%)

1139

(0.2%)

1867

(0.3%)

p 1165277608568

(52%)

284425

(24%)

178084

(15%)

94200

(8%)

288491276358

(96%)

10066

(3.5%)

1227

(0.4%)

840

(0.3%)

GOOD Low Med High

e 60093 (64%) 854 (75%) 1365 (73%)

p 35407 (12%) 10914 (5.7%) 21033 (22%)

5185 (51.5%) 797 (65%) 459 (55%)

Goo

d e

ne

MCEnergy

Low Cal

High Cal

Gamma

BAD

BADGOOD

GOODALL

ALL

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GLAST LAT Bkg Rejection Italy

““Tree” cutsTree” cuts

• Using IM xml file in classification • Develop a “Node” structure parsing the xml IM output• Check of cuts

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GLAST LAT Bkg Rejection Italy

ID

predicate

predicateID

0/1

CT approachCT approach

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GLAST LAT Bkg Rejection Italy

All Total No Lo Med Hi

(all) 722,594 314,226 122,081 114,224 172,063

(good)64,110

(20.4%)

86,190

(70.6%)

90,201

(79.0%)

138,793

(80.7%)

Signal events splitSignal events split

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GLAST LAT Bkg Rejection Italy

Good Cal E

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GLAST LAT Bkg Rejection Italy

Starting with Classification TreesStarting with Classification Trees

• Use of R program – rpart (recursive partitioning)• Searching to optimize “goodCal”• For each step rpart reports the cost-complexity of the tree, the

number of splits, the relative error and finally the error that it obtains from a process of cross validation, with the corresponding sigma.

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GLAST LAT Bkg Rejection Italy

Classification Trees with rpartClassification Trees with rpart

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GLAST LAT Bkg Rejection Italy

Classification Trees with rpartClassification Trees with rpart

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GLAST LAT Bkg Rejection Italy

Classification Trees with rpartClassification Trees with rpart

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GLAST LAT Bkg Rejection Italy

Classification Trees with rpartClassification Trees with rpart

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GLAST LAT Bkg Rejection Italy

One Tree per E binOne Tree per E bin

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GLAST LAT Bkg Rejection Italy

One Tree per E binOne Tree per E bin

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GLAST LAT Bkg Rejection Italy

One Tree per E binOne Tree per E bin

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GLAST LAT Bkg Rejection Italy

Classification Trees with RClassification Trees with R

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rpart Classificationrpart Classification

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GLAST LAT Bkg Rejection Italy

rpart Classificationrpart Classification

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GLAST LAT Bkg Rejection Italy

Error costsError costs

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GLAST LAT Bkg Rejection Italy

Error CostsError Costs

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GLAST LAT Bkg Rejection Italy

Error CostsError Costs

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GLAST LAT Bkg Rejection Italy

Random ForestRandom Forest

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GLAST LAT Bkg Rejection Italy

Random ForestsRandom Forests

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GLAST LAT Bkg Rejection Italy

Random ForestsRandom Forests

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GLAST LAT Bkg Rejection Italy

Random ForestsRandom Forests

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GLAST LAT Bkg Rejection Italy

rForest packagerForest package

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GLAST LAT Bkg Rejection Italy

ConclusionsConclusions

• Work is progressing…• Work on new variables started• More results will come…