1. Background studies for the ILD vertex detector Rita De Masi IPHC-Strasbourg

2. Characteristics of the study GuineaPig 0.7.4-b e + e - pairs bremsstrahlung photons spent beam Mokka-06-06 detector model LDCPrime_02Sc_p01 VXD_side_band_electronic option 0 rangeCut 1mm LorentzTransformationAngle 7 mrad

3. e + e - pairs background in z … z (mm) hits/mm 2 /BX layer1 layer2 layer3 layer4 layer5 ~ 0.07

4. …and   (  ) hits/mm 2 /BX layer1 layer2 layer3 layer4 layer5 ~ 0.1 ~ 0.05

5. vtx-z of particles hitting the VTX

6. Cut on |vtx z| distribution in z… |vtxz|<3000 mm z (mm) hits/mm 2 /BX |vtxz|>3000 mm layer1 layer2 layer3 layer4 layer5

7. …and   (  ) hits/mm 2 /BX |vtxz|<3000 mm |vtxz|>3000 mm layer1 layer2 layer3 layer4 layer5

8. beamstrahlung photons (preliminary) out of 50 BX (~2x10 7 generated particles) no hits in the VTX neither direct nor indirect

9. spent beam (very very preliminary) ~ 0.04 hits/mm 2 /BX on layer1 (~50% of pairs contribution) BUT study out of only 1/20th of BX (due to extremely long simulation time)

10. Conclusion Pairs: - all elements along the beam line Beamstrahlung  further study  Spent beam: “ Bhabbha, …