PrimEx p0 radiative width extractionEric ClintonUniversity of Massachusetts AmherstJuly 19, 2007

OutlineData Source and cutsEvent selectionHybrid Mass Signal enhancementYieldsYields over entire HyCal acceptance presented for information on Incoherent photo-pion production onlySystematic effects from yield extractionSimulationResultsSytematic Error Analysis

Data Source and Cutsmysql -h primexdb -u primex_user book_keeping -b --execute="select run from run_list where radiator='A' and target='carbon' and type='pi0' and production='good';" > run_list.example

mysql -h primexdb -u primex_user book_keeping -b --execute="select run from run_list where radiator='B' and target='carbon' and type='pi0' and production='good';" > run_list.example1.) Two or more clusters/event. 2.) Minimum three (3) (PbWO4 or lead glass) detectors to define a cluster. 3.) 50 MeV or greater central (PbWO4 or lead glass) crystal detector energy in cluster. 4.) 10 MeV or greater minimum deposited energy in (PbWO4 or lead glass) detector. 5.) Max cluster energy 8 GeV. 6.) gg invariant mass greater than 0.085 GeV in at least one of the cluster pairs.7.) Elasticity (cluster pair energy sum/tagger energy) greater than 0.70.8.) Cluster energy greater than 0.5 GeV.9.) Cluster X or Y position must be greater than 4.1 cm.10.) Cluster pair energy sum between 3.5 and 6.5 GeV -- additional software cut not imposed on the skim, but imposed later:11.) Timing cut of -15 ns to +5ns.pi0gains used as calibration

Event selectionEliminate Tagger and HyCal combinatoricsLikelihood Event entries have invariant mass, elasticity, and timingWhich entry to choose in a mutli-entry event?Which is "most likely"?Fit invariant mass, elasticity, timing signal and backgroundFitted signal lineshape as probability density function (PDF)Evaluate the PDF for each parameter for each entry.Three individual likelihoods. PDFInvariant mass, PDFElasticity, PDFTimingTotal likelihood = PDFInvariant mass PDFElasticity PDFTiming

Entry with highest total likelihood "wins".

Misidentification any systematics?No. MisID is random, and event selection tends to pick smaller production angle pions.

Rotation of 2-D data onto 1-DTry to enhance signal to noiseOriginal 2-D dataElasticity vs.Invariant MassNew 1-D signalAKA Hybrid Mass

Additional Diagonal Data CutWarningdeparture from analysis note

Apply Additional Cut and VetoWarningdeparture from analysis noteResultGreatly improved signal to noiseRemoves 3rd order curvature from backgroundRequires well understood vetoVeto systematic error small in comparison to fit error and other systematic effect improvements

Plateau Elastic Pion YieldsAdditional minimization of signal to noiseTimingElastic p0 as a function of the timing cutIntegration Range (left, below)Elastic p0 as a function of the integration rangeFitting Range (right, below)Elastic p0 as a function of the fitting range

Original timing cut/data source

Timing cut set to 5 ns

Timing cut vs. pion yield plateau

Integration range plateau

Fitting range plateau

Selected Hybrid Mass Fits

p0 yields as a function of production angle.These yields are extractedfrom a data set where the diagonal and veto cuts areapplied.

Final radiative width MUSTcorrect for veto Photon Misidentification.

Yield extraction for various signal and background models

Simulation WorkThrown with E-Channel Photon flux weightingPrimakoff (with FSI), Coherent (Cornell with FSI), Incoherent (Glauber)Energy correction addedEnergy lost out back of HyCal, out of cluster maskAdded back about 10% of energyTracking threshold tunedProper shower developmentResolution and centroid tunedGet invariant mass right to proper mock physicsVet the SimulationPush 4 vectors from experiment thru simSee how p0 candidate spectrum look, look for lossesTurn off detectors, see how acceptance behaves

Putting physics events thru the Simulation Around 99.2% fidelity

Turning off glass detectorsHyCal Tungstate Acceptance Only

Efficienciesas a function of the photo-pion process, HyCal Tungstate acceptance

Geometric efficiency and reconstruction (cut) efficiency

HyCal tungstate acceptance

Turning off cluster energy and invariant mass cuts

Fit to Data, and Extracted WidthHyCal Tungstate AcceptanceExtracted width 8.166 eV 0.133 eV (1.63%)

Acceptance Corrected Cross SectionsPRELIMINARYHyCal Tungstate Acceptance

Systematic error sources?

Extracted yields over the entire pion angle range must be stable as these parameters are varied.

Systematic Effects from Yield Extraction HyCal Tungstate acceptanceNominal 8.166NACluster Position Finding MethodMethod 0: 8.044-1.50Method 1: 8.202+0.43* (+)Method 2: 8.156-0.13* (-)Method 4: 8.195+0.35

Lineshape (degrees of freedom)***DG3Po: 8.173+0.09* (-)TG2Po: 8.188+0.26* (+)

Integration range (nom. = 0.013 HMUs) 0.0108.102-0.79 % 0.011 8.155-0.13 % 0.012 8.148-0.21 % 0.013 8.166NA 0.014 8.170+0.04 % 0.016 8.206+0.48 % 0.018 8.242+0.923 %No systemtatic effect will be claimed. Fit errors go up faster than any shifts above, and yield plateau for smaller pion angles is present.

***Nominal = Double gaussians with 2nd order polynominal DG3Po = Double gaussians with 3rd order polynomial TG2Po = Triple gaussians with 2rd order polynominal

Fit Range (nominal = 0.029 HMUs) 0.0268.105-0.74 % 0.0278.123-0.52 % * (-) 0.028 8.152-0.18 % 0.029 8.166NA 0.030 8.192+0.31% * (+) 0.031 8.130-0.44 % 0.032 8.141-0.31 % 0.033 8.120-0.57 % 0.034 8.134-0.39 %

Total Error will be asymmetric since many of systematic effects tend to go in only one direction.All positive contribution will be added in quadrature for the total positive systematic errorVice versa for the negative contributions

Error Accounting HyCal Tungstate acceptance

ResultHyCal Tungstate Acceptance

Gp0gg = 8.166 eV 0.133 eV +0.102 eV 0.100 eVGp0gg = 8.166 eV 1.63 % +1.25% - 1.23%

Future workWork another nuclear incoherent generatorLatest from Tulio in handEvolve cross sections to the weighted mean photon energyConjoined analysisLead Target Data?

Extra slides

The Vetohow it changes the angular spectrums

Extracting a Photon Misidentification EfficiencyPME = 0.80 0.057% (HYCALCLUSTER veto flag == 4) PME = 2.20 0.16% (HYCALCLUSTER veto flag == 3) PME = 2.80 0.21% (HYCALCLUSTER veto flag == 2) PME = 3.20 0.23% (HYCALCLUSTER veto flag == 1) ** ongoing work

Photon flux

Poor Elasticity

Energy CorrectionAcross entire HyCal acceptance

Tracking Threshold, resolution, and centroid tuning

Turning off glass detectorsEntire HyCal Acceptance

Turning off tungstate detectorsEntire HyCal Acceptance

Efficienciesas a function of the photo-pion process, entire HyCal acceptance

Geometric efficiency and reconstruction (cut) efficiency.

Entire HyCal Acceptance