1. Evolution of Beam-Beam-Background Simulation at CLIC André Sailer(PH-LCD) May 12,2010

2. Content • Beam-Beam Simulation with GuineaPig • Simulation and Background in the Full Detector

3. Simulation with GuineaPig(GP) • Initial distribution of Particles (bunch shape, charge density) • Largest impact on number of pairs • Provided by Beam Physics Group (B.Dalena, D.Schulte) • Two data sets, different horizontal emmitance

4. Incoherent Pairs from GP • Wider beam, less particles (350k  310k) • But energy distribution per angle very similar

5. Detector Simulation • Using Geant4 based Mokka • Based on ILD concept • Different • Crossing angle • Magnetic field (4 Tesla) • Beam pipes • Calorimeters

6. Vertex Detector • CLIC01_ILD • Vertex Detector • 3 double Layers at R=31/46/60mm • All layers 25cm long • 50 µm Active Silicon • Threshold: 3.4 keV • 4 Tesla Magnetic Field • Hadronic Calorimeter • 8.5λ • Absorber: Tungsten, 1cm thick, 77 layers Vertex Detector André Sailer, LC Physics/Detector Meeting

7. Forward Region • First Simulations done with geometry right bottom • Different magnetic Field options • AntiDID, Solenoid, DID only • Hits in VXD (all Layers) (10BX) • 19000 71000 33000

8. Changes I • AntiDID not an option, because it costs to much Luminosity, from now on only Solenoid field • Using “real” CLIC QD0 • Hits in the Vertex Detector (all layers, 10BX) • 70k down to 60k

9. Changes II • Larger inner radius for BeamCal • 20 to 25 mm • Beam pipe with a single radius • Hits in the VXD increases (all Layers, 10BX) • From 60k to 93k

10. Changes III • Using Racetrack profile • Not an option, because of QD0 design • Reduces number of backscatters from beam pipes • Hits in VXD (all Layers, 10BX) • From 93k to 41k

11. Changes IV • Conical beam pipe that fits with QD0 design • Hits reduced again • 41k to 21k

12. Changes V • Moved BeamCal forward, decreased inner radius • Space for Intra-Train-Feedback • Hits: • 21k to 27k • Same geometry new Beam Profiles • Hits 24k