update on beamtest 06 cu psf study c. cecchi s. germani m. pepe università di perugia and infn...
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Update onUpdate on Beamtest 06 Beamtest 06 CU PSF studyCU PSF study
C. CecchiS. Germani
M. Pepe
Università di Perugia and INFN
Gamma-ray Large Area Gamma-ray Large Area Space TelescopeSpace Telescope
Beam Test Worksop II May 15-17, 2006
Beam Test Worksop 2
Pisa, May 16th, 2006
C. Cecchi S. Germani M. Pepe 2
Simulated DataSimulated Data
BeamtestRelease v1r0801p0– PS simulation from beamtest06 v4r0 (updated)– 4.5M e- generated with E=2.5 GeV /angle(0°, 20°,
40°)– 4.5M e- generated with E= 1 GeV /angle– 800k e- from SLAC pipeline /angle(0°, 40°)
0°
20°
40°
• Analyzed using Gleam v6r12 hit the towers at 3 different Beam Angles (0° and 40° are the same as Mass Production (SLAC))
Beam Test Worksop 2
Pisa, May 16th, 2006
C. Cecchi S. Germani M. Pepe 3
Basic Event SelectionBasic Event Selection
We used the Merit ntuple after adding PS variables
- goodCal = EvtEnergyCorr>20 && EvtEnergyCorr<BeamEnergy-goodNumTracks = TkrNumTracks > 0-goodTag = e_silicon[i] > 0 i=0, 3
e_silicon[0]e_silicon[1]
e_silicon[3]e_silicon[2]
Beam Test Worksop 2
Pisa, May 16th, 2006
C. Cecchi S. Germani M. Pepe 4
Vertex and TrackVertex and Track
• Good Vertex Merit Variable VtxStatus = 34 : 2 tracks vertex + two tracks share first
hit 162 : 34 + DOCA location lies inside track hits else use only BestTrack
After cuts we have roughly the same number of events in each of the two categories
Beam Test Worksop 2
Pisa, May 16th, 2006
C. Cecchi S. Germani M. Pepe 5
Energy and DirectionEnergy and Direction
• Reconstructed Energy compare EvtEnergyCorr
TagEnergy (BeamEnergy – E_rec)
• Photon Direction derived using first two tag detectors (Ptag)
• PSF defined from angular error:
– good Vertex acos(Ptag·PVtx)
– best Track acos(Ptag·PTkr1)
Beam Test Worksop 2
Pisa, May 16th, 2006
C. Cecchi S. Germani M. Pepe 6
Tagger Silicon DetectorTagger Silicon Detector
Beam Test Worksop 2
Pisa, May 16th, 2006
C. Cecchi S. Germani M. Pepe 7
Angle Error (Vtx Scaled)Angle Error (Vtx Scaled)2 GeV (SLAC)
2.5 GeV
1 GeV
Beam Test Worksop 2
Pisa, May 16th, 2006
C. Cecchi S. Germani M. Pepe 8
McEnergy (e- 2.5 GeV)McEnergy (e- 2.5 GeV)
0 deg 40 deg
McEnergy =ΣMcEγ MultiGamma Any M_gamOne Gamma M_gam==1
The MultiGamma effect is small we can neglect to distinguish between 1 and multigamma events
Beam Test Worksop 2
Pisa, May 16th, 2006
C. Cecchi S. Germani M. Pepe 9
Energy Rec. Comparison 1 Energy Rec. Comparison 1 GammaGamma
0 deg 40 deg
e- 2.5 GeVe- 2.5 GeV
Resolution of the tagger worse at low energies wrt EvtEnergy visible in the scaled PSF
Beam Test Worksop 2
Pisa, May 16th, 2006
C. Cecchi S. Germani M. Pepe 10
Tagger EnergyTagger Energy
40 deg
Tagger Energy = BeamEnergy–E_rec
0 deg
e- 2.5 GeVe- 2.5 GeV
Beam Test Worksop 2
Pisa, May 16th, 2006
C. Cecchi S. Germani M. Pepe 11
EvtEnergyCorrEvtEnergyCorr
0 deg
40 deg
20 dege- 2.5 GeVe- 2.5 GeV
Beam Test Worksop 2
Pisa, May 16th, 2006
C. Cecchi S. Germani M. Pepe 12
McDirErr – Measured McDirErr – Measured DirErrDirErr
e- 2.5 GeVe- 2.5 GeVVtx EventsVtx Events
Beam Test Worksop 2
Pisa, May 16th, 2006
C. Cecchi S. Germani M. Pepe 13
Tagger Selection (4Si vs Tagger Selection (4Si vs 2Si)2Si)
0 deg
Requiring e_silicon>0 (signal) only from the first two Tagger Planes does not affect the PSF !
e- 2.5 GeVe- 2.5 GeV
Beam Test Worksop 2
Pisa, May 16th, 2006
C. Cecchi S. Germani M. Pepe 14
Electron Beam 2.5 GeV Electron Beam 2.5 GeV
Vtx Events
Tkr Events
Beam Test Worksop 2
Pisa, May 16th, 2006
C. Cecchi S. Germani M. Pepe 15
SLAC Mass Production vs 2.5 SLAC Mass Production vs 2.5 GeV GeV
Beam Test Worksop 2
Pisa, May 16th, 2006
C. Cecchi S. Germani M. Pepe 16
e- 2.5GeV – 2GeV – 1 GeVe- 2.5GeV – 2GeV – 1 GeV
Beam Test Worksop 2
Pisa, May 16th, 2006
C. Cecchi S. Germani M. Pepe 17
Evaluating PSF Evaluating PSF ErrorError
• The number of events within 68% is N68
• The error on N68 is ΔN68=sqrt(NTOT×0.68×(1-0.68)) [Binomial]
• ΔPSF68 is obtained computing the quantiles corresponding to a number of events equal to N68 ±ΔN68
68%
PSF68
Beam Test Worksop 2
Pisa, May 16th, 2006
C. Cecchi S. Germani M. Pepe 18
PSF Error one beam energy vs PSF Error one beam energy vs allall
Vtx 0 deg
Goal Error Level
Beam Test Worksop 2
Pisa, May 16th, 2006
C. Cecchi S. Germani M. Pepe 19
ConclusionConclusionss
• 1 and 2.5 GeV e- simulated on PG-farm 27M analysed • 2 GeV SLAC production 1.6M (e-) analysed
• No difference selecting 1 or M• Tag energy difference only on scaled PSF at low energies• Simulated and reconstructed energies gives same results on
PSF• Selection with only the first two silicon higher photon
energy
• Is 800K e-/angle/energy enough to reach 1% error on PSF?No at low energies...... At higher energies may depend on true rejection
• Cross check results using only not scaled PSF
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