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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 (Zeuthen). Colorado, Cracow, DESY(Zeuthen), JINR Dubna, London (UC), Minsk (BSU), Prague, Protvino ( IHEP), Tel Aviv Collaboration. The very Forward Calorimeter Collaboration.

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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 (Zeuthen) Colorado, Cracow, DESY(Zeuthen), JINR Dubna, London (UC), Minsk (BSU), Prague, Protvino ( IHEP), Tel Aviv Collaboration IEEE

  2. The very Forward Calorimeter Collaboration see: PRC R&D 01/02

  3. The TESLA Detector

  4. Functions of the very Forward Detectors • Detection of Electrons and Photons at very low angle • Measurement of the Luminosity (LAT) • Shielding of the inner Detector • Fast Beam Diagnostics (LCAL) LCAL 300 cm VTX FTD IP LAT

  5. Measurement of the Luminosity Beam Offsets: < 200 μm Inner Radius of Cal. < 0.75 μm Distance of Cals. < 60 μm Center-of-Mass Energy: Process dependent Gauge Process: e+e- e+e- Goal: 10-4 Precision (LEP: 3.4 10-4) • Physics Case: sZ for Giga-Z Two Fermion Cross Section at high Energy, Threshold Scans Requirements on Alignment and mechanical Precision (rough Estimate) • Technology: Si-W Sandwich Calorimeter • MC Simulations Optimisation of Shape and Segmantation • Alignment with Laser Beams

  6. Measurement of the Luminosity e+e-e+e- (g) Simulations with BHWIDE 8 cm Q Resolution as function of the depth 28 cm Rings 20 -20 300 330

  7. Some systematics in Q Reconstruction Q Resolution as function of the number of cylinders

  8. Fast Beam Diagnostics e+ e- • e+e- pairs from beamstrahlung are deflected into the LCAL • 15000 e+e- per BX 10 – 20 TeV • 10 MGy per year Rad. hard sensors • Technologies: Diamond-W Sandwich Scintillator crystals Gas ionisation chamber GeV Deposited energy over R and f contains information about beam parameters

  9. Schematic views Heavy crystals W-Diamond sandwich sensor Space for electronics

  10. 1st Results: Single Parameter Analysis

  11. Detection of Electrons and Photons at very low angle • Tag of two photon events

  12. Detection of Electrons and Photons at very low angle • essential parameters: Small Molière radius High granularity Longitudinal segmentation • Two photon event rejection e+e- e+e-m+m- (Severe background for particle searches) 500 BX • Electromagnetic fakes 1% from physics 2% from fluctuations

  13. Real Beam Simulations Includes seismic motions, Delay of Beam Feedback System, Lumi Optimisation etc.

  14. Sensor prototyping, Diamonds • Different surface treatments : • #1 – substrate side polished; 300 um • #2 – cut substrate; 200 um • #3 – growth side polished; 300 um • #4 – both sides polished; 300 um Diamond; Size: 12x12 mm 2 Metallisation: 10 nm Ti + 400nm Au Current (I) dependence on the voltage (V) Ohmic behavior for ‘ramping up/down’, hysteresis Charge collection distance is saturated to 60 mm at ~300V

  15. Sensor prototyping, Crystals Light Yield from direct coupling Plastic scintilator and using a fibre Study with heavy crystals (Cerenkov light) is going on ~ 25 %

  16. Sensor prototyping, C3F8 Gas Ionisation Chamber Pads for charge collection Beam Test 26 GeV e- beam, 103s-1 Current vs Voltage Pressure vessel

  17. Summary • The Instrumentation of the Very Forward Region of a • LC is a challenging Topic • MC Simulations to optimise the Design are progressing • Different Detector Technologies will be compared • Tests with Sensor Prototypes have been started • After about two Years we will present a TDR • The Goal is to start with the construction and test of a prototype

  18. Charge collection distance measurements Qmeas. = Qcreated x ccd / L ADC Sr90 PA delay diamond Scint. discr & PM1 Gate discr PM2 Using electrons from a Sr90 source (mips)

  19. Sensor prototyping and lab tests • Current (I) dependence on the voltage (V) • Ohmic behavior for ‘ramping up/down’, hysteresis • Resistance in the order of 100 TOhm • Current decays with time • After 24 h nearly 1/2

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