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
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
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.
Disrupted beam in 2 mrad crossing 2.1 10 7 Seryi QD0QF1 Particle loss in QF1 3.2% of E<0.65E0 400 Watts
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.
Pairs at Z = 315 cm r 2 cm X (cm) 20 mrad w/o compensation 20 mrad w compensation 2 mrad