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Very Forward Region Instrumentation

Very Forward Region Instrumentation. Wolfgang Lohmann, DESY. Basic functions: Hermeticity to small polar angles Fast and precise Luminosity measuremt Shielding of the inner detectors -. Shielding function. Due to the small bunch size s x ~100nm, s y ~5 nm

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Very Forward Region Instrumentation

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  1. Very Forward Region Instrumentation Wolfgang Lohmann, DESY Basic functions: • Hermeticity to small polar angles • Fast and precise Luminosity measuremt • Shielding of the inner detectors- Valencia Workshop

  2. Shielding function Due to the small bunch size sx~100nm, sy~5 nm and the large bunch charge, N x 1010/bunch, beamstrahlung becomes important 20mrad solenoid lots of e+e- pairs LDC meeting 20mrad DID

  3. Current design Head-on or small X-angle Bhabha Scattering LumiCal 26 < q < 82 mrad BeamCal 4 < q < 28 mrad 300 cm VTX Beampipe FTD IP PhotoCal downstream (100 < q < 400 mrad L* = 4m

  4. Precise Luminosity Measurement, LumiCal 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 (MC simulations, BHLUMI) Inner Radius of Cal.: < 4 μm Distance between Cals.: < 100 μm Radial beam position: < 0.6 mm < 0.6 mm

  6. Technology Sensor carriers Si/W sandwich calorimeter, simulations at advanced level. No hardware devolepment up to now. Absorber carriers Mechanical frame: Decouple sensor support from absorber support structure

  7. Comparison head-on, 2, 20 mrad Radial beam shift: 400mm Centered around the outgoing beam Centered around the detector axis For a 20 mrad design LumiCal MUST be centered around the outgoing beam-pipe!

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

  9. background Background in the LumiCal : (500 GeV, TDR) Zero or small X-angle: negligible 20 mrad X-angle: 3-5 TeV Beamstrahlung pair background using serpentine field Number of Bhabha events as a function of the inner Radius of LumiCal 250 GeV Background from beamstrahlung

  10. BeamCal Zero (or 2 mrad) crossing angle • e+e-Pairs from Beamstrahlung are deflected into the BeamCal • 15000 e+e- per BX 10 – 20 TeV (10 MGy per year) • Radiation hard sensors needed GeV 20 mrad Crossing angle Background in the BeamCal : (500 Gev, TDR) Zero or small X-angle: 30 TeV/BX 20 mrad X-angle: 60 TeV/BX

  11. Detection of High Energy Electrons and Photons (Detector Hermeticity) √s = 500 GeV Single Electrons of 50, 100 and 250 GeV, detection efficiency as a function of R (‘high background region’) Detection efficiency as a function of the pad-size Red – high BG blue – low BG Message: Electrons can be detected!

  12. Beam Parameter Determination with BeamCal Fast Lumi estimate and feedback for beam steering Observables total energy first radial moment angular spread L/R, U/D F/B asymmetries 20 mrad crossing angle Also simultaneous determination of several beam parameter is feasible, but: Correlations! Analysis in preparation PRELIMINARY!

  13. 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

  14. Technologies for the BeamCal: • Radiation Hard • Fast • Compact Heavy crystals W-Diamond sandwich sensor Space for electronics

  15. 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 !)

  16. 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

  17. Diamond Sensor Performance Linearity Studies with High Intensities (PS fast beam extraction) 105 particles/10 ns Response to mip Particle flux, N/cm2/10ns

  18. Univ. of Colorado, Boulder, AGH Univ., INP & Jagiell. Univ. Cracow, JINR, Dubna, NCPHEP, Minsk, FZU, Prague, IHEP, Protvino, TAU, Tel Aviv, DESY, Zeuthen look to our web-page: http//www.zeuthen-desy.de/LC/FCAL We would be happy to welcome you to fight together!

  19. Summary • Many (and promising) results in simulations/design studies • Concept for a Luminometer for small crossing angle is advanced, 20 mrad needs a different design – work to be done • compact and fine segmented calorimeters necessary, needs R&D • radiation hard sensors for the inner calorimeter – needs R&D • Mechanics design just started, needs effort • no electronics concept so far • Prototype tests mandatory Remark: • The instrumentation of the forward region is relatively independent of the detector concept,

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