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PFA Development – Definitions and Preparation

PFA Development – Definitions and Preparation. 0) Generate some events w/G4 in proper format Check Sampling Fractions ECAL, HCAL separately How? Photons, electrons in ECAL Neutral hadrons in HCAL (no ECAL int.) Charged Pions in HCAL (don’t forget ECAL mips). Detector – SDFeb05 Sci HCAL.

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PFA Development – Definitions and Preparation

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  1. PFA Development – Definitions and Preparation • 0) Generate some events w/G4 in proper format • Check Sampling Fractions ECAL, HCAL separately • How? • Photons, electrons in ECAL • Neutral hadrons in HCAL (no ECAL int.) • Charged Pions in HCAL (don’t forget ECAL mips) Detector – SDFeb05 Sci HCAL • KL0 in HCAL • -> sf = 0.06 • Photons in ECAL • -> sf = 0.012

  2. Hadron Comparisons Pions N - ? KL0 KL0 G4 Physics List? – under investigation

  3. PFA Development – Definitions and Preparation • 2a) Single Particle Response ->Analytic Perfect PFA • Expected values for E resolution? • Why not!? -> G4 problem? Go Back To 0) • 2b) Analog/Digital Readout!? • 2a) Calibration • How? • With/without threshold cut? • Realistic methods? • 2b) Choice of threshold cut • Necessary? • Realistic?

  4. Analytic Perfect PFA – SDFeb05 Detector Model Hadrons (Pions) Photons No neutral E! 57 GeV 22 GeV 11 GeV Photon resolution = 22.5 x .199 = 0.94 GeV -> PPFA = 19%/E Neutral H resolution = 10.7 x .48 = 1.57 GeV

  5. PFA Development – Definitions and Preparation • 3) Perfect PFA with Detector Effects • Equal to 2a)? • Better than 30%/√E? • 4) Now ready for PFA development 1.95 GeV 1.31 GeV -> PPFA = 28%/E

  6. PFA Development – Definitions and Preparation • 4) Document and archive all of the above for each Detector Model • Web site for archived plots and detector documentation • Also needs to include special cuts, etc. • 5) Now ready for PFA development • Examples of PFA use in detector optimization/evaluation ->

  7. Calorimeter Absorber Optimization – PFA Application • PFA optimization - beginning of hadron showers separated (longitudinally) from beginning of EM showers . . . P(e,) = 1 – Ce, e-x/X0 Ce, = (1,7/9) P(h) = 1 – Ch e-l/I Ch = 1 • So, in first layers of calorimeter, wantP (e,)>>P (h) • ->x/X0 >> l/I • ->I/X0should be as large as possible Dense, Non-magnetic Less Dense, Non-magnetic * . . . Use these for ECAL * Note ~X2 difference in I for W/Pb – important for HCAL later

  8. W Pb SS Cu Shower Probabilities in ECAL (25 X0) P() P() -P(h) P(interaction) W Absorber P(h) X0 X0 • P() reaches ~100% while P (h) still <20% • -> W,Pb probability differences >> SS,Cu • -> better shower separation in dense material

  9. W Pb SS W Pb SS 2) OnceP(e,)-> 1and ’s are fully contained (end of ECAL), wantP(h)-> 1as fast as possible . . . P(h) dP(h)/dI I11232453 I Length (cm) . . . W performs better than SS and Pb for HCAL

  10. Z jets in SS/W HCAL – Absorber Comparison SD SS HCAL 34 layers – 2 cm SS (1 X0) 1 cm Scintillator 4 I • SD W HCAL • 55 layers – • 0.7 cm W (2 X0) • 1 cm Scintillator • 4 I ~0.9 m ~1 m Same event - different shower shape in W compared to SS?

  11. 3) And, hadron showers should be as compact as possible . . . Single 5 GeV  Single 5 GeV  SS W • Energy in fixed cone size : • -> means ~same for SS/W • -> rms ~10% smaller in W • Tighter showers in W rms . . . W looks like the best choice for HCAL cone

  12. 4) Energy resolution comparisons for SS, W . . . Single 5 GeV Pion SS W E/mean ~ 24% E/mean ~ 20% • Energy measurement in calorimeter – Analog ECAL, Digital HCAL • -> /mean smaller in W HCAL • -> same behavior for analog HCAL W – 2 X0 sampling SS – 1 X0 sampling

  13. Single 5 GeV Pion – Number of hits (1/3 mip thresh) SS W • More hits in W HCAL than in SS • -> 30% more hits in the HCAL for W • -> better digital resolution for W! W – 2 X0 sampling SS – 1 X0 sampling

  14. Single 5 GeV Pion – Visible Energy in HCAL SS W • More visible energy in W HCAL • -> better analog resolution in W W – 2 X0 sampling SS – 1 X0 sampling

  15. W – 2 X0 sampling SS – 1 X0 sampling e+e- -> Z (jets) – PFA performance Fits SS W True PFA -> SS 33%/E True PFA -> W 28%/E Better PFA performance with the W HCAL for conical showers . . . however, simple iterative cone reconstructs smaller fraction of events*

  16. W – 2 X0 sampling SS – 1 X0 sampling Single particle, PFA resolution comparison results . . . E/mean E/mean   SS W W SS E/mean ↓, X0↑ ! Coarser X0 sampling gives better E!? E/mean ↓, I↓ Finer I sampling gives better E • . . . W looks like the best choice for HCAL • -> hadron E resolution depends on I, not X0

  17. HCAL Readout Optimization – PFA Application Dense HCALs (W absorber) - 4 I in ~82.5 cm IR -> OR • SDFeb05 RPC HCAL • 55 layers of 0.7 cm W/0.8 cm RPC • 1.2 mm gas gap • Sampling Fraction ~0.0025%!!! SDFeb05 SCI HCAL 55 layers of 0.7 cm W/0.8 cm Scin. Sampling fraction ~6%

  18. First – Calorimeter Performances Scin. – Analog Readout RPC – Digital Readout Hard to compete with no visible energy? Not a great start, but lets continue anyway 

  19. Track/CAL Cell Association Algorithm Scin. – Analog Readout RPC – Digital Readout Resolution still better in scintillator, but algorithm reproduces perfect ID in both cases

  20. Neutral Finding Algorithm Scin. – Analog Readout RPC – Digital Readout Once again, very similar performance

  21. PFA Results Scin. – Analog Readout RPC – Digital Readout PFA performance is very similar (with same cuts) but reflects underlying CAL resolution

  22. Confusion – Leftover Hits! Scin. – Analog Readout RPC – Digital Readout Better use of hits in RPC? – good since aren’t that many

  23. Summary • For LC Detector, HCAL should be as dense as possible • -> hadron showers more compact in W – smaller HCAL volume • -> more I per cm – smaller Solenoid B-field volume • -> more layers for fixed total I HCAL – better resolution since more sampling • -> more hits - better digital resolution • -> more visible E – better analog resolution • PFA (incomplete) used to optimize HCAL absorber • First look at comparison of analog (scintillator) and digital (RPC) readout modes for HCAL • -> very little visible E, number of hits in W/RPC showers – try finer I sampling? • -> compared analog and digital modes with same analysis program • Once again, PFA used to evaluate detector performance

  24. Particle Flow Algorithm – Horse or Cart? • PFA used for : • Detector Optimization – absorber type/thickness, longitudinal segmentation and transverse granularity, B-field, tracking volume (radius), etc. -> Detector Model(s) • Detector Model evaluation – comparisons, tradeoff evaluations, etc. • -> PFA is the Horse! Physicists still have to do work!

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