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Update on Beamtest 06 CU PSF study

This update provides the latest findings from the Beamtest 06 CU PSF study, including simulated data, event selection criteria, energy and direction reconstruction comparisons, and evaluation of the PSF error. Conclusions highlight the impact of tag energy on PSF and the effectiveness of selecting events with the first two silicon detectors.

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Update on Beamtest 06 CU PSF study

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  1. Update on Beamtest 06 CU PSF study C. Cecchi S. Germani M. Pepe Università di Perugia and INFN Gamma-ray Large Area Space Telescope Beam Test Worksop II May 15-17, 2006

  2. 40° 20° 0° Simulated 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°) • Analyzed using Gleam v6r12 • hit the towers at • 3 different Beam Angles • (0° and 40° are the • same as Mass Production (SLAC))

  3. e_silicon[0] e_silicon[1] e_silicon[2] e_silicon[3] Basic 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

  4. Vertex 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

  5. Energy 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)

  6. Tagger Silicon Detector

  7. Angle Error (Vtx Scaled) 2 GeV (SLAC) 2.5 GeV 1 GeV

  8. McEnergy (e- 2.5 GeV) MultiGamma  Any M_gam One Gamma  M_gam==1 McEnergy =ΣMcEγ 0 deg 40 deg The MultiGamma effect is small we can neglect to distinguish between 1 and multigamma events

  9. Energy Rec. Comparison 1 Gamma e- 2.5 GeV 0 deg 40 deg Resolution of the tagger worse at low energies wrt EvtEnergy  visible in the scaled PSF

  10. Tagger Energy e- 2.5 GeV Tagger Energy = BeamEnergy–E_rec 0 deg 40 deg

  11. EvtEnergyCorr 20 deg e- 2.5 GeV 0 deg 40 deg

  12. McDirErr – Measured DirErr e- 2.5 GeV Vtx Events

  13. Tagger Selection (4Si vs 2Si) e- 2.5 GeV 0 deg Requiring e_silicon>0 (signal) only from the first two Tagger Planes does not affect the PSF !

  14. Electron Beam 2.5 GeV Vtx Events Tkr Events

  15. SLAC Mass Production vs 2.5 GeV

  16. e- 2.5GeV – 2GeV – 1 GeV

  17. Evaluating PSF Error • 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 PSF68 68%

  18. PSF Error one beam energy vs all Vtx 0 deg Goal Error Level

  19. Conclusions • 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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