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Instrumentation of the Very Forward Region of a Linear Collider Detector

Instrumentation of the Very Forward Region of a Linear Collider Detector. Wolfgang Lohmann, DESY. Simulation studies on several designs. SiD Forward Masking, Calorimetry & Tracking, T. Maruyama. 0.5. Used by H. Yamamoto. 0.4. 113mrad. 0.3. Inst. Mask. W. 0.2. QD0. W. 0.1.

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Instrumentation of the Very Forward Region of a Linear Collider Detector

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  1. Instrumentation of the Very Forward Region of a Linear Collider Detector Wolfgang Lohmann, DESY LCWS Stanford

  2. Simulation studies on several designs SiD Forward Masking, Calorimetry & Tracking,T. Maruyama 0.5 Used by H. Yamamoto 0.4 113mrad 0.3 Inst. Mask W 0.2 QD0 W 0.1 Pair-LuMon 46mrad 0 LowZ Mask BeamPipe Exit radius 2cm @ 3.5m -0.1 W W -0.2 ECAL Support Tube -0.3 -0.4 HCAL YOKE 5 Tesla -0.5 4 0 0.5 1 1.5 2 2.5 3 3.5

  3. Functions of the very Forward Detectors • Measurement of the Luminosity with precision O(<10-3) • Detection of Electrons and Photons at very low angle – extend hermeticity (Important for Searches) • Fast Beam Diagnostics • Shielding of the inner Detectors L* = 4m 300 cm VTX FTD IP LumiCal: 26 < q < 82 mrad BeamCal: 4 < q < 28 mrad PhotoCal: 100 < q < 400 mrad LumiCal BeamCal

  4. Measurement of the Luminosity Two Fermion Cross Sections at High Energy, Physics Case: Giga-Z , e+e- W+W- Gauge Process: e+e- e+e- (g) Goal: <10-3 Precision • Technology: Si-W Sandwich Calorimeter Optimisation of Shape and Segmentation, Key Requirements on the Design • MC Simulations

  5. Requirements on the Mechanical Design LumiCal IP LumiCal < 4 μm Requirements on Alignment and mechanical Precision (rough Estimate) Inner Radius of Cal.: < 1-4 μm Distance between Cals.: < 60 μm Radial beam position: < 0.7 mm < 0.7 mm

  6. Concept for the Mechanical Frame Decouple sensor frame from absorber frame Sensor carriers Absorber carriers

  7. Laser Alignment Test • CCD camera, • He-Ne red laser, • Laser translated in 50 mm steps Jagiellonian Univ. Cracow Photonics Group reconstruction of the laser spot (x,y) position on CCD camera

  8. Performance Simulations for e+e- e+e-(g) 0.13e-3 rad 0.11e-3 rad 30 layers 15 rings Constant value Constant value Simulation: Bhwide(Bhabha)+CIRCE(Beamstrahlung)+beamspread Event selection: acceptance, energy balance, azimuthal and angular symmetry. 4 layers 11 layers 15 layers 10 rings 10 rings 20 rings

  9. Determination of the Acceptance region Eout-Ein P = Eout+Ein Out In P 1 ring 2 rings 3 rings

  10. Determination of shower Coordinates Strip version ΔE~0.31√E

  11. Fast Beam Diagnostics e+ e- • e+e-Pairs from Beamstrahlung are deflected into the BeamCal • 15000 e+e- per BX 10 – 20 TeV Rad. hard sensors • 10 MGy per year • direct Photons for q < 200 mrad GeV Technologies: Diamond-W Sandwich Scintillator Crystals Gas Ionisation Chamber

  12. Schematic Views Heavy crystals W-Diamond sandwich sensor Space for electronics

  13. Beam Parameter Determination with BeamCal Observables first radial moment thrust value total energy angular spread L/R, U/D F/B asymmetries

  14. and with PhotoCal IP >100m Photons from Beamstrahlung Heavy gas ionisation Calorimeter nominal setting (550 nm x 5 nm) L/R, U/D F/B asymmetries of energy in the angular tails

  15. Detection of High Energy Electrons and Photons √s = 500 GeV Single Electrons of 50, 100 and 250 GeV, detection efficiency as a function of R Detection efficiency as a function of the electron energy for different positions Message: Electrons can be detected!

  16. Realistic beam simulation Efficiency to identify energetic electrons and photons (E > 200 GeV) √s = 500 GeV Includes seismic motions, Delay of Beam Feedback System, Lumi Optimisation etc. (G. White) Fake rate

  17. Sensor prototyping, Crystals Light Yield from direct coupling Compared with GEANT4 Simulation, good agreement and using a fibre ~ 15 % Similar results for lead glass Crystals (Cerenkov light !)

  18. Sensor prototyping, Diamonds Scint.+PMT& Diamond (+ PA) gate signal ADC Pads Pm1&2 May,August/2004 test beams CERN PS Hadron beam – 3,5 GeV 2 operation modes: Slow extraction ~105-106 / s fast extraction ~105-107 / ~10ns (Wide range intensities) Diamond samples (CVD): - Freiburg - GPI (Moscow) - Element6

  19. Diamond Sensor Performance Linearity Studies with High Intensities Response to mip Pm-Pm Pm-Pads Pm-Pad2 Pm-Pad1 Pm-Pad3 Pm-Pad4

  20. Summary • A lot of activity in simulations/design studies…… • High energy electron detection down to small polar angles is feasible with compact and fine segmented calorimeters • Concept for a Luminometer is progressing • Studies with sensors started- needs more effort • Prototype tests mandatory Remarks • The instrumentation of the forward region is independent of the detector concept, • but it depends on the crossing angle scheme

  21. Shower LEAKAGE in old (TDR) and new LumiCal design Shower in LumiCal (new design) Shower in LAT (TDR design)

  22. Diamond performance as function of the absorbed dose Linearity of a heavy gas calorimeter (IHEP testbeam)

  23. Comparison 500 GeV - 1TeV Comparison Sampling Heavy Crystal Comparison Sampling Heavy Crystal

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