PrimEx p0 radiative width extraction

1
PrimEx p0 radiative width extraction

• Eric Clinton
• University of Massachusetts Amherst
• June 21, 2007

2
Outline

• Data Source and cuts
• Event selection
• Hybrid Mass Signal enhancement
• Yields
• Systematic effects from yield extraction
• Simulation
• Results
• Sytematic Error Analysis

3
Data Source and Cuts

• mysql -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'" gt 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'" gt run_list.example

• 1.) 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
  3.8 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 caliubration

4
Event selectionEliminate Tagger and HyCal
combinatorics

• Likelihood
• Event entries have invariant mass, elasticity,
  and timing
• Which entry to choose in a mutli-entry event?
• Which is "most likely"?
• Fit invariant mass, elasticity, timing signal and
  background
• Fitted signal lineshape as probability density
  function (PDF)
• Evaluate the PDF for each parameter for each
  entry.
• Three individual likelihoods. PDFInvariant mass,
  PDFElasticity, PDFTiming
• Total likelihood PDFInvariant mass
  PDFElasticity PDFTiming
• Entry with highest total likelihood "wins".

5
Getting Final Likelihood spectrumTake entire
Most Likely spectrum as event sample

• Most Likely invariant mass spectrum

• Final Likelihood
• PDFInvariant mass PDFElasticity PDFTiming

6
Misidentification any systematics?No. MisID
is random, and event selection tends to pick
smaller production angle pions.
7
Rotation of 2-D data onto 1-DTry to enhance
signal to noise

• Original 2-D data
• Elasticity vs.Invariant Mass

• New 1-D signal
• AKA Hybrid Mass

8
Selected Hybrid Mass Fits
9
p0 yields as a function of production angle.
10
Systematic error sources?

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

11
Lineshape Degrees of Freedomentire HyCal
acceptance
12
Integration/BG subtraction rangeentire HyCal
acceptance
13
Stability of Fit Range entire HyCal acceptance
14
The Vetohow it changes the angular spectrums
15
Extracting a Photon Misidentification
EfficiencyPME 0.76
16
Simulation Work

• Thrown with E-Channel Photon flux weighting
• Primakoff (with FSI), Coherent (Cornell with
  FSI), Incoherent (Glauber)
• Energy correction added
• Energy lost out back of HyCal, out of cluster
  mask
• Added back about 10 of energy
• Tracking threshold tuned
• Proper shower development
• Resolution and centroid tuned
• Get invariant mass right to proper mock physics
• Vet the Simulation
• Push 4 vectors from experiment thru sim
• See how p0 candidate spectrum look, look for
  losses
• Turn off detectors, see how acceptance behaves

17
Photon flux
18
Poor Elasticity
19
Energy CorrectionAcross entire HyCal acceptance
20
Tracking Threshold, resolution, and centroid
tuning
21
Putting physics events thru the Simulation
Around 99.2 fidelity
22
Turning off glass detectorsEntire HyCal
Acceptance
23
Turning off tungstate detectorsEntire HyCal
Acceptance
24
Turning off glass detectorsHyCal Tungstate
Acceptance Only
25
Efficienciesas a function of the photo-pion
process, entire HyCal acceptance
26
Geometric efficiency and reconstruction (cut)
efficiency.Entire HyCal Acceptance
27
Efficienciesas a function of the photo-pion
process, HyCal Tungstate acceptance
28
Geometric efficiency and reconstruction (cut)
efficiency HyCal tungstate acceptance
29
Fit to Data, and Extracted WidthEntire HyCal
Acceptance Extracted width 7.870 eV 0.139 eV
(1.77)
30
Fit to Data, and Extracted WidthHyCal Tungstate
AcceptanceExtracted width 7.859 eV 0.146 eV
(1.86)
31
Acceptance Corrected Cross Sections
Entire HyCal Acceptance
PRELIMINARY
HyCal Tungstate Acceptance
32
Systematic Error Entire HyCal acceptance

• Nominal 7.870 NA
• Veto width 7.779 -1.16
• Cluster Position Finding Method
• Method 0 7.720 -1.90
• Method 1 7.888 0.23 ()
• Method 2 7.938 0.86
• Method 4 7.849 -0.27
• Lineshape (degrees of freedom)
• DG3Sp 7.859 -0.14 (-)
• TG3Po 7.931 0.77 ()
• Integration range (Nominal cutoff 1.0)
• 3 width 7.802 -0.86 (-)
• 2 width 7.841 -0.36
• 0.5 width 7.966 1.22
• 0.3 width 7.966 1.22 ()

• Fit Range (nominal 0.030 HMUs
• -27, 27 7.760 -1.40
• -33, 33 7.973 1.31
• Average 7.867 -0.03 (-)
• -30, 33 7.838 -0.41
• -30, 27 7.877 0.09
• Average 7.862 -0.10 (-)
• -27,30 7.745 -1.58
• -33, 30 8.002 1.68
• Average 7.870 0.04 ()
• Adding the () gives positive sytematic
  shift 1.46
• Adding the (-) gives negative systematic
  shift -0.88
• Systematic Error 1.46, -0.88

Nominal Double gaussians with 3rd order
polynominal DG3Sp Double gaussians with
3rd order spline TG3Po Triple gaussians
with 3rd order polynominal
33
Systematic Error HyCal Tungstate acceptance

• Nominal 7.859 NA
• Veto width 7.774 -1.16
• Cluster Position Finding Method
• Method 0 7.699 -2.04
• Method 1 7.827 -0.41 (-)
• Method 2 7.881 0.24
• Method 4 7.670 -2.40
• Lineshape (degrees of freedom)
• DG3Sp 7.859 -0.00 (-)
• TG3Po 7.891 0.41 ()
• Integration range (Nominal cutoff 1.0)
• 5 width 7.788 -0.90 (-)
• 2 width 7.813 -0.59
• 0.5 width 7.877 0.22
• 0.2 width 7.938 1.00 ()

• Fit Range (nominal 0.030 HMUs
• -27, 27 7.809 -0.63
• -33, 33 7.888 0.36
• Average 7.867 -0.1 (-)
• -30, 33 7.824 -0.45
• -30, 27 7.888 0.36
• Average 7.862 -0.03 (-)
• -27,30 7.777 -1.04
• -33, 30 7.941 1.04
• Average 7.870 0.00 ()
• Adding the () gives positive sytematic
  shift 1.08
• Adding the (-) gives negative systematic
  shift -0.99
• Systematic Error 1.08, -0.99

Nominal Double gaussians with 3rd order
polynominal DG3Sp Double gaussians with
3rd order spline TG3Po Triple gaussians
with 3rd order polynominal
34
Total Error budget

• Entire HyCal Acceptance
• Statistical
• Veto Off 1.77
• Veto On 1.62
• Photon Flux 1.10
• Systematic (Yield Extrn.) 1.46, -0.88
• Branching Ratio 0.03
• Target Thickness 0.04
• Veto (if used) 0.05

• HyCal Tungstate Acceptance
• Statistical
• Veto Off 1.86
• Veto On 1.75
• Photon Flux 1.10
• Systematic (Yield Extrn.) 1.08, -0.99
• Branching Ratio 0.03
• Target Thickness 0.04
• Veto (if used) 0.05

35
Result

• Entire HyCal Acceptance
• Gp0?gg 7.870 eV 0.139 eV 0.144 eV 0.111 eV
• Gp0?gg 7.870 eV 1.77 1.83 - 1.41

• HyCal Tungstate Acceptance
• Gp0?gg 7.859 eV 0.146 eV 0.121 eV 0.116 eV
• Gp0?gg 7.859 eV 1.86 1.54 - 1.48

36
Future work

• Work another nuclear incoherent generator
• Evolve cross sections to the weighted mean photon
  energy
• Lead Target Data?