1. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG The BeamCal Simulation Project Progress Report Progress Report Keith Drake, Tera Dunn, Jack Gill, Keith Drake, Tera Dunn, Jack Gill, Gleb Oleinik, Uriel Nauenberg Gleb Oleinik, Uriel Nauenberg University of Colorado at Boulder University of Colorado at Boulder

2. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Two photon process cross section cross section about 10 5 larger than SUSY cross section. Serious source of background for SUSY if not tagged. Pointed out by our group around 1998 Beam Calorimeter Studies

3. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG e + e + e - e - γ γ q, l - - q, l in the detector in the detector Very forward into BEAMCAL Very forward into BEAMCAL 2 Photon Process

4. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Beam Cal 7 mrad exit -7 mrad ent. Lumi Cal

5. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Solenoid field keeps the low energy charged particle in the forward direction. Beam hole is at 7 mrad. Need to add an x field component to move low energy charged particles in the 7 mrad direction. Anti-DiD dipole field proposed by Andrei Seryi.

6. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG

7. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Beamstrahlung e + e - pairs. Energy deposited in 0.25 x0.25 cm 2 cells.

8. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Outside Beam Pipe Integrated Energy into the Beam Pipe is ~TeV

9. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Shower in Beamcal from 2 γ process alone head-on view side view core of shower Radius of 25 mm

10. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG head on view electron from 2γ process beamstrahlung side view

11. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Beamstrahlung Energy Deposition in a Tile Tile at start of BeamCal Tile 3.0 cm in

12. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Beamstrahlung Energy Deposition in a Tile Tile 4.7 cm in Tile 6.0 cm in

13. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Consequences of Beamstrahlung Energy Deposition Deposition  Energy Deposition is not Gaussian until one reaches a depth > 3 cms. reaches a depth > 3 cms.  Distribution is very wide and hence affects energy resolution if we subtract an average energy resolution if we subtract an average value. value.  This problem is seen in the study how to measure the electron/positron energies. Resolution. the electron/positron energies. Resolution.

14. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Beamstrahlung with average subtracted Electron from 2 photon overlayed

15. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Clustering Cuts in Depth and Energy, Example 1 Cut 30 mm Cut 10 MeV Beamstrahlung + Electron from 2-photon Beamstrahlung Alone Work in Progress

16. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Clustering Cuts in Depth and Energy, Example 2 Beamstrahlung + Electron from 2-photon Beamstrahlung Alone

17. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Clustering Cuts in Depth and Energy, Example 3 Beamstrahlung + Electron from 2-photon Beamstrahlung Alone

18. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Energy observed as a function of distance from center of BeamCal Entrance Beam Pipe Exit Beam Pipe φ Δφ = 5 deg r Δr = 1 mm

19. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Energy Deposition versus r and φ Φ=0.0Φ=30.0 Distance from center of beamcal (mm) 30.0 Effect of Exit Beam Pipe

20. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Energy Deposition versus r and φ 150.0 Effect of Entrance Beam Pipe Distance from center of beamcal (mm) Effect of Entrance Beam Pipe 180.0 Distance from center of beamcal (mm) Φ=150.0 Φ=180.0

21. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Full detector Within a radius of 25mm no clustering Full Detector with clustering sensors

22. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Fraction of Energy Observed within a Radius of 0.5 cm of Electron Path No clustering cuts With clustering cuts

23. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Fraction of Energy Observed within a Radius of 1.0 cm of Electron Path No clustering cuts With clustering cuts

24. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG No clustering cuts With clustering cuts Fraction of Energy Observed within a Radius of 2.0 cm of Electron Path

25. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Fraction of Energy Observed within a Radius of 3.0 cm of Electron Path

26. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Energy Resolution of High Energy Electrons {E(measured)- E(expected)} /E(expected) Best Possible Resolution No Beamstrahlung effects included

27. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Energy Resolution of High Energy Electrons {E(measured)- E(expected)} /E(expected) Energy Resolution with Beamstrahlung Included. Average Substracted. Only energy deposited in a 25 mm radius from maximum. Sum energy over full Beamcal thickness. Effect of Beamstrhalung fluctuation in resolution clearly has an effect

28. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Energy Resolution of High Energy Electrons {E(measured)- E(expected)} /E(expected) Energy Resolution. Beamstrahlung Included and Average Substracted. Measurements from 3.0 cm in and Including only cells with more than 10 MeV energy deposited.

29. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Energy resolution of the reconstruction of the electrons from 2-photon events including the effects of beamstrahlung Preliminary results Using Bayesian Statistical Analysis

30. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Case of no Beamstrahlung Included in analysis Case of Best Analysis with Beamstrahlung Included. Beamstrahlung Included. Exit Beam Pipe Region Exit Beam Pipe Region

31. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Reason for Resolution Tail Measured Energy loss due to cuts

32. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Work to be Done  Understand the low energy tails of the energy resolution distribution. Develop a better scan.  What is the missing Pt distribution of 2 photon events given the resolution.  Study the resolution of new geometries.

33. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG

34. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG

35. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG

36. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Work to be Done  Optimize signal to Background.  Check all our Calculations.  Find other analysis techniques that reduce the beamstrahlung fluctuations and hence improve the signal resolution.  Study the effect of this analysis on SUSY signal. Missing Pt limits.

37. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG

38. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG

39. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Study of a Scintillator Calorimeter We are simulating a scintillator based calorimeter where the tiles are offset in alternate layers. We are making now a great deal of progress.

40. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG π 0 mostly low p 100 GeV γ s are well separated 5 cm 100 GeV

41. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG ALCPG 0 0.5 1.0 0.25 0.75 ····· θ · · · · φ Best separation Worst separation 5 cm 1.25 cm Geometrical Arrangement ScintillatorPanels

42. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Track Following into the Calorimeter Low momentum curlers

43. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Cluster Correlation with Charged Tracks Success Probability Energy cluster in the calorimeter associated with a charged track interaction Success Conclude that it is a neutral cluster Failure

44. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG ALCPG The Chi-Square Structure μ i = average photon energy deposited in ith tile σ i = standard deviation in the energy deposition H ij = σ i σ j χ 2 = Σ (x i – μ i )H ij (x j – μ j ) where x i is the energy deposited by the shower being tested in the ith tile. i,j =1 9

45. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG We are now in the middle of trying to separate photon clusters by means of the chi-square method. Hard problem. Crucial aspect of pattern recognition and calorimeter resolution.

46. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Fitted γ direction from shower energy distribution 50 GeV 20 GeV Z vs R

47. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Study of the Characteristics of Silicon Photomultipliers

48. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG New Silicon Photo-Detectors 2mm 2mm Bias Voltage ~40 volts ~40 volts Photonique, SA Pulsar, Russia + Moscow Eng. Physics Inst. Scintillator performance

49. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG

50. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG 2mm scint., cosmic rays 1 photo elec. 5 photo elec. 8 photo elec. Need to Improve Resolution 20 < t < 70 nsec 0 < t < 200 nsec Similar resolution

51. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG

52. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Sipm attached to the center of surface of the scintillator tile

53. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG New Nat. Inst. PHA

54. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Special Budgetary Issue ILC R&D in DOE (Paul Grannis) awarded us a $20 K late award that could not be sent to CU but could only be deposited at SLAC because of the timing. I request that I use these funds for BaBar work and be allowed to used BaBar funds deposited in Colorado for ILC R&D work.

55. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Because ILC R&D funds become available in ~ July the funds cover 2 years of BaBar work 1 year of differential housing costs for Nagel $5 K 1 year travel costs from Colorado to SLAC $5 K The total award from ILC R&D is $53 K

56. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG The University has contributed to my research a total of $38 K towards support of a Research Associate since I have become Chair of the Boulder Faculty Assembly and my research time is now limited. I propose to use these and the ILC R&D funds towards the Research Associate if DOE accepts the ILC-BaBar fund exchange.

57. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Modules Each module = ~12 tons The Calorimeter

58. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Removal of Charged Track Hits Extrapolatio n of charged tracks Charged hits removed TrackInteractTrackInteract Jason Gray, Jiaxin Yu

59. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Pattern Recognition of Showers Chris Geraci

60. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Chi Square Separation, 1 st order 100 GeV π 0 Odd layers 100 GeV π 0 Even layers Sarah Moll Joseph Proulx

61. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG e + e + e - e - γ γ q, l - - q, l in the detector in the detector Very forward into BEAMCAL Very forward into BEAMCAL 2 Photon Process Discussion in Beam Cal section at end

62. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Study the efficiency to observe the electron and positron of the two photon process above the beamstrahlung background Essential to remove this background in the study of Supersymmetry in the dynamic region of low Pt. Needed to measure the masses.

63. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Testing GEANT 4.0 No field, 50 MeVmuons No field, 50 GeV muons Evidence for multiple scattering air in beam pipe

64. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG 50 MeV, no field, forward 50 MeV, solenoid on, forward Solenoid field shrinks mult. Scat.

65. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Beamstrahlung Distribution with Solenoid + Anti-DiD No beam pipes Beam pipes Beam pipes Entrance Exit Difficult region to detect 2 photon process

66. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG GEANT 4.0 seems to be working properly We have fixed various bugs in collaboration with SLAC team. All Simulation is work in progress.

67. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Hardware Studies Keith Drake, Elliot Smith

68. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Long Term Tests of Scint. Fiber Stability

69. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Latest Pulse Distribution from Photonique/Russia 6 photoelectrons 6 photoelectrons 10 photoelectrons

70. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Pulse National Inst........ 8 pe 3 pe 1 pe Scan every 2.5 nsec

71. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Our Measurements Blue LED, 10nsec, 2.5 volts drive 50 nsec gate noiseless SiPD 6 photo-elec.

72. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG 1st 10 nsec2nd 10 nsec 3rd 10 nsec4th 10 nsec

73. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Cosmic Rays in a 1 cm Thick Scintillator 1 pe 2pe 4pe 20 < t < 70 nsec0 < t < 200 nsec poorer resolution

74. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG 10 < t < 2030 < t < 40 40 < t < 50 60 < t < 70 1cm scint

75. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Pulse Height versus Temperature Gain of SiPD Increases ~x4 Noisy SiPD Could not detect peaks Room temp -30 0 C Needs to be repeated with New SiPDs; noiseless

76. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG 10 < t < 20 30 < t < 40 40 < t < 50 nsec60 < t < 70 nsec 2 mm scint

77. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG By time tagging we are observing the photons arriving in time sequence. Possibility to use this to improve resolution. Need beam tests to check this hypothesis.

78. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Work still in progress. Comparison with Russian plots indicate 100 Mhz x 4 (measuring pulse height every 2.5 nsec) not enough resolution. National Instruments has just released a 2 Gigahertz unit. Using our trick of x4 will allow us to scan every 0.125 nsec. A demo is on its way here to check whether 8 bits resolution is good enough.

79. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Conclusions A new revolution in photo-detection. A lot of improvements still possible. A lot of work to be done in this area. If one is bold and reckless one may say that “It may revolutionize calorimetry resolution.”

80. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG Conclusions Our simulation work with the undergraduates is moving ahead. A lot of work needs to be done still. Need manpower help. Most of the pieces are in place to study Z and W mass resolution.

81. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG

82. ILC – The International Linear Collider Project Univ. of Colorado, Boulder, April 28/08 April 28/2008-ALCPG We helped with the organization of the Linear Collider Workshop and the various ALCPG meetings up to but not including Vancouver