1 PEBS - Positron Electron Balloon Spectrometer Detector Concept CERN, January 2009 Stefan Schael I. Physikalisches Institut B RWTH Aachen

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PEBS Experiment 4 1,6 m improve the momentum resolution by a factor of 10 !

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8 RICH SRD

PEBS-ECAL TRD 1 TRD m 1.0 m 0.86 m 2.0 m Physic-Programm: Positron – Spectrum 1 GeV GeV Electron – Spectrum 1 GeV – 1000 GeV B-Field: 0.7 Tesla Superconducting magnet, 850 kg Acceptance: 3000 cm 2 sr 6 Si-Inner-Tracker Planes (red), single Point resolution mm 4 ScFi-Outer Tracker Planes (pink) single Point resolution mm momentum resolution: 1000 GeV 2 TRD‘s, each with 12 layers, Proton Rejection GeV Electron Efficiency 80% 11 X0 ECAL, Weight 650 kg Weight: 1700 kg

10 80 cm long ladders !

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13 Inner Si TrackerUpper SciFi Tracker Circle-Fit Inner Si Tracker: B=0.7 Tesla, L=1m, nLayer=6, σ x =0.010 mm

14 Inner Si TrackerUpper SciFi Tracker Angle-Point - Measurement Inner Si Tracker: B=0.7 Tesla, Lin =1.0 m, nLayer=4, σ in =0.010 mm Upper SciFi-Tracker: Lup=1.2 m, nLayer=4, σ up =0.050 mm

15 Inner Si TrackerUpper SciFi Tracker Angle-Angle - Measurement Inner Si Tracker: B=0.7 Tesla, Lin =1.0 m, nLayer=4, σ in =0.010 mm Upper SciFi-Tracker: Lup =1.2 m, nLayer=4, σ out =0.050 mm Lower SciFi-Tracker: Ldown=1.2 m, nLayer=4, σ out =0.050 mm

16 Track-Fit Performance at P=100 GeV

17 No correlation visible for Circle-Fit and Angle-Point measurement => take the weighted mean

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19 Magnet Top View, center of the coils

20 Magnet Side View, center of the coils Coil

21 Z=2.2m L=1m z [m] z1z1 z2z2 z3z3

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29 Electron-Efficiency 70%

30 Proton Rejection: Ecal 10 3, E/P=10 + TRD

PEBS - RICH Physic-Programm: Positron/Electron – Spectrum up to 200 GeV He3/He4 for 1 GeV/n <= E/n <= 100 GeV/n Be10/Be9 for 1 GeV/n <= E/n <= 100 GeV/n Weight Budget for RICH 600 kg TRD 1 TRD 2 Gas RICH Gas RICH Aerogel RICH Aerogel RICH

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TRD 1 TRD 2 U-TRD SRD PEBS - SRD Physic-Programm: Positron – Spectrum 1 GeV GeV Electron – Spectrum 1 GeV – 3000 GeV U-TRD: 12 Layer upper TRD Proton Rejection 36 Layer TRD GeV Electron Efficiency 70% Weight 50 kg Weight Budget for SRD (green) 400 kg SRD Acceptance 100,000 cm 2 sr

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