1. HEP Tel Aviv University LumiCal (pads design) Simulation Ronen Ingbir FCAL Simulation meeting, Zeuthen Tel Aviv University HEP experimental Group Collaboration High precision design

2. HEP Tel Aviv University Presentation Outline Reconstruction Algorithms Detector Simulation (& Design optimization ) Fast Detector Simulation ( Luminosity ) Events Selection Physics Simulation Electronics Simulation ( Basic model ) And More … Analyses Collaboration High precision design

3. HEP Tel Aviv University Electrons/Bhabhas Bhabha Pure electrons Electron energy (GeV) Pure electrons Bhabha Collaboration High precision design Electrons/Positrons - Geant-3 integrated generator. Bhabha scattering - BHWIDE generator

4. Beamstrahlung and Beam spread HEP Tel Aviv University Collaboration High precision design Beamstrahlung - Circe generator. Beam spread – Included separately (home made routine).

5. HEP Tel Aviv University 250GeV 26 mrad Events selection - old approach Gaussian fit and energy calibration based tail cut Acceptance cut was based on the leakage Detector signal Collaboration High precision design

6. HEP Tel Aviv University 33 mrad Energy Resolution The most significant event selection cut is the geometric acceptance cut. This cut was used to get the best energy, angular resolutions and minimum biases. Events selection Collaboration High precision design

7. HEP Tel Aviv University Left-Right balance R L Simulation distribution Distribution after acceptance and energy balance selection Right side detector signal Left side detector signal Right signal - Left signal Collaboration High precision design

8. HEP Tel Aviv University Out In Eout - Ein Eout + Ein P= New selection cut Ring Signal Collaboration High precision design

9. HEP Tel Aviv University Eout-Ein Eout+Ein P= Out In Collaboration High precision design

10. HEP Tel Aviv University 3 cylinders 3 Rings 2 cylinders 3 Rings 1 cylinders 3 Rings Eout-Ein Eout+Ein P= Collaboration High precision design

11. HEP Tel Aviv University Reconstruction Algorithms Collaboration High precision design Angular reconstruction: ‘Normal’ energy weight Logarithmic weighting with selection cutoff. Logarithmic weighting per layer (Bogdan’s algorithm). ‘Real life’ approach. Energy reconstruction: Energy resolution. Energy calibration.

12. HEP Tel Aviv University Reconstruction Algorithm Events Num. We explored two reconstruction algorithms: The log. weight fun. was designed to reduce steps in a granulated detector : 1. Selection of significant cells. 2. Log. smoothing. Log. weight. E weight. T.C Awes et al. Nucl. Inst. Meth. A311 (1992) 130. Collaboration High precision design

13. HEP Tel Aviv University Logarithmic Constant Constant value After selecting: We explored a more systematic approach. The first step is finding the best constant to use under two criteria: 1. Best resolution. 2. Minimum bias. 400 GeV Collaboration High precision design

14. HEP Tel Aviv University Energy dependent constant The goal is to find a global weight function. Is the the log. weight constant really a constant ? Constant value Collaboration High precision design

15. HEP Tel Aviv University Shower reconstruction Num. of Cells Num. of Sectors Num. of Cylinders Energy portion (%) En>90% What happens when we select the best log. weight constant ? Shower size Log. Weight Selection Most of the information is in the selected cells. Collaboration High precision design

16. HEP Tel Aviv University Algorithms Comparison Collaboration High precision design 15 Cylinders40 Cylinders64 Cylinders Pads - Full Log. Pads - Bogdans log. Strips - Bogdans log. 13*10e-55*10e-5 14*10e-5 4*10e-5 1.Two methods are equivalent - reason : in both cases Theta is reconstructed directly. 2.There is a saturation limit for the resolution (before 64 cylinders).

17. HEP Tel Aviv University Real life algorithm Working with both sides of the detector and looking at the difference between the reconstructed properties: (In real life we don’t have generated properties) Collaboration High precision design

18. HEP Tel Aviv University ‘Pure’ electrons simulation Bhabha+Beam+BS(5e-4) Bias study Collaboration High precision design

19. Two plots convinced us that the bias observed is not detector design dependent nor imperfect algorithm. HEP Tel Aviv University 48 sectors design X (cm) Y (cm) Bias study Collaboration High precision design

20. HEP Tel Aviv University Magnetic field Collaboration High precision design

21. HEP Tel Aviv University Energy resolution Ntuple No cuts With cuts Pure electrons 31 % 29%29% Bhabha 42 % 24 % Bhabha + Beamstrahlung 45 % 24 % Bhabha + Beamstrahlung + Beam spread (0.05%) 46 % 25 % Bhabha + Beamstrahlung + Beam spread (0.5%) 49 % 29 % Collaboration High precision design

22. HEP Tel Aviv University Angular resolution Collaboration High precision design

23. Pad design 0.34 cm Tungsten 0.31 cm Silicon Cell Size 1.3cm*2cm> 1.3cm*6cm< ~1 Radiation length ~1 Radius Moliere HEP Tel Aviv University 15 cylinders * 24 sectors * 30 rings = 10800 cells R L 8 cm 28 cm 6.10 m Collaboration High precision design

24. HEP Tel Aviv University 0.34 cm Tungsten 0.31 cm Silicon 0.55 cm Tungsten 0.1 cm Silicon Dense design Collaboration High precision design

25. HEP Tel Aviv University 30 radiation length detector 47 radiation length detector Z (cm) Detector Signal 0.8cm 1.1cm Moliere radius & Radiation length Collaboration High precision design

26. HEP Tel Aviv University Energy Resolution Events New geometric acceptance Collaboration High precision design

27. HEP Tel Aviv University Detector optimization Collaboration High precision design

28. HEP Tel Aviv University Optimization Collaboration High precision design

29. HEP Tel Aviv University Optimization Collaboration High precision design

30. HEP Tel Aviv University Margins around cells Having margins Means Losing Information Collaboration High precision design

31. HEP Tel Aviv University One cylinder One sector Radius (cm) (deg) Detector signal Loosing information Collaboration High precision design

32. HEP Tel Aviv University Margins in between cells Energy resolutionPolar resolution Collaboration High precision design

33. HEP Tel Aviv University Our basic detector is designed with 30 rings * 24 sectors * 15 cylinders = 10,800 channels Do we use these channels in the most effective way ? Maximum peak shower design 30 rings 15 cylinders 20 cylinders 10 cylinders 24 sectors * 15 rings * (10 cylinders + 20 cylinders) = 10,800 channels 4 rings15 rings11 rings 10 cylinders Collaboration High precision design

34. HEP Tel Aviv University Maximum peak shower design Basic Design Angular resolution improvement without changing the number of channels Other properties remain the same Constant value Polar reconstruction 0.11e-3 rad 0.13e-3 rad Collaboration High precision design

35. HEP Tel Aviv University Electronics Simulation Collaboration High precision design Noise Function Case Study in which: minmax (Signal+noise) - (signal) 70% Noise Cells example Noise signal N N (Basic model) Random selection of cells

36. HEP Tel Aviv University Collaboration High precision design 0% 50% 25% 10% Signal (including Dead Cells)Signal (including Noise Cells) 100% 0% 50% NN Noise Cells / Dead Cells Case Study:

37. HEP Tel Aviv University Collaboration High precision design (%) Having ‘Dead’ cells affects both the reconstruction of the energy and the angles in the same way. Having Noise in the cells: 1.Assuming noise function with no extreme values. 2.Assuming high signal to noise ratio. 3.Using log weight function with revised cut value (that takes into account the new average ‘zero level’). Similar resolutions Performance with noise and dead cells preliminary

38. HEP Tel Aviv University Fast Detector Simulation Collaboration High precision design Motivation : High statistics in required to notice precision of : There is an analytic calculation (and approximation) : (Which is the precision goal of the ILC) Is it a good approximation ? This calculation takes into account only the Bhabha angular distribution, how does other factors affect (backgrounds, detector design, electronics noise) ? We need a mechanism to actually count events, as if it was real life.

39. HEP Tel Aviv University High Statistics MC BHWIDE + fast detector simulation Collaboration High precision design

40. HEP Tel Aviv University R&D status High statistics MC Electronics noise and ‘Dead’ Cells Collaboration High precision design Design optimization (Dense design, Margins in between cells, Maximum peak shower design) Pure electron MC Detector properties Events selection ‘Real physics’ MC Bhabha + Beamstrahlung + Beamspread Reconstruction Algorithms

41. HEP Tel Aviv University Future Steps Collaboration High precision design ‘Real physics’ MC Final optimization Luminosity with a crossing angle Luminosity with polarised beams ( Gideon Alexander ) Pad/Strip comparison Geant-4 transition Additional background studies (two photon events, beamstrahlung hitting the detector) Additional hardware design constrains and electronics simulation (digitisation, reality noise parameters, silicon production constrains)

42. HEP Tel Aviv University THE END Collaboration High precision design