1. Status of ongoing studies for comparing 2-mrad and 20-mrad IRs T. Maruyama SLAC

2. Beam parameters 500 GeV TESLA TDR –3.4  10 34 cm -2 s -1 (6.8  10 -3 pb -1 / train) –2  10 10 e- –2820 bunches per train @ 5 Hz –337 ns bunch spacing Physics rates  (pb)events/train e+e-  qq2.70.02 e+e-  WW7.60.05

3. IP Backgrounds:# particles/BX R max > 1 cm, |z|<200 cm e+/e- pairs120K270   hadrons0.8 events*   muons2.3 events* Radiative Bhabha466K 0 Disrupted primary beam Beamstrahlung photons Background Sources Machine Backgrounds: Synchrotron Radiation Muons Production at collimators Direct Beam Loss Beam-Gas Collimator edge scattering Neutron back-shine from Dump * Tim’s updates for COLD

4. Two Crossing Angle Schemes with SiD Detector 20 mrad2 mrad L* = 3.51 m L* = 4.05 m R =2.5 cm R = 1 cm

5. Two crossing angle schemes Beam steering Spin precession ~60 mrad ~0.2% depolarization Compensation: Detector integrated dipole (DID) Z-dependent Bx (~800 Gauss max.) Larger background Beam steering in the extraction line. 20 mrad crossing QD0 QF1 Beam extraction through QF1 coil pocket 2 mrad crossing Solenoid compensation is necessary. Extraction line beam diagnostics may not work.

6. Disrupted beam in 2 mrad crossing 2.1  10 7 Seryi QD0QF1 Particle loss in QF1 3.2% of E<0.65E0 400 Watts

7. Radiative Bhabhas in 2 mrad QD0QF1 Particle loss: E (GeV)Power (W) QD0 1.6  10 5 0.36 QF1 2.8  10 6 6.3

8. Sync radiations in 2 mr Sync radiations hit the face of QF1 RED: halo, upstream quads GREEN: halo, QD0 BLUE: disrupted beam, QD0 Disrupted beam with sync photons Beam can be extracted through QF1 coil pocket. QF1 fringe field ~3 kGauss.

9. Pairs at Z = 315 cm r 2 cm X (cm) 20 mrad w/o compensation 20 mrad w compensation 2 mrad

10. Pairs 272 e+/e- / BX 1.2 e+/e- /BX VXD Forward tracker Barrel Tracker ECAL R max distribution VXD hits  hadrons 1 evt/BX ~2 VXD hits  muons 2 evt/BX ~2 VXD hits

11. Tracker Backgrounds Barrel Forward Background in Si Tracker is small: < 5 hits Forward Layer #1 has 21 hits.

12. To do 20 mrad –Solenoid compensation –Yuri’s new extraction line 2 mrad –Yuri’s new extraction line –Different QF1 design