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IR Beamline and Sync Radiation

IR Beamline and Sync Radiation. Takashi Maruyama. Collimation. No beam loss within 400 m of IP Muon background can be acceptable. No sync radiations directly hitting the detector Spoilers SP2 and SP4 are set at the collimation depth. Final Focus collimation. Energy collimation.

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IR Beamline and Sync Radiation

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  1. IR Beamline and Sync Radiation Takashi Maruyama

  2. Collimation • No beam loss within 400 m of IP • Muon background can be acceptable. • No sync radiations directly hitting the detector • Spoilers SP2 and SP4 are set at the collimation depth. Final Focus collimation Energy collimation Betatron collimation SP2 SP4

  3. Collimation studies IP GEANT3 • Particle tracking and interaction simulation • Decay TURTLE • STRUCT • GEANT3 • GEANT4 • MuCarlo • MARS FF Collimators 295 cm E-slit sp4 sp2 a4 a2 sp3 sp1 a3 1480 m

  4. SiD Forward Region Support Tube LumiCal BeamCal Borated Poly W Mask Beampipe

  5. Pair background • Beam-beam interaction generates ~75 K e+/e-/BX • No material can be placed inside the pairs. • Mask M1 contains the pairs and protects the detector from back splash. • Want to place the vertex detector at R=1.4 cm. • Want a hermetic detector to small polar angles. Conventional sync radiation masks are not compatible with these requirements. Collimate the beam so that no sync radiations directly hit the detector .

  6. 14 mrad crossing geometry Apertures: Low Z QD1S QD0 Beampipe@IP R=1.0 cm@z=-3.51 m 1.2cm@0.0m 1.5 cm @5.5-6.56m 1.5 cm @2.85-2.95m

  7. Sync radiation from Soft Bend Drozhdin 90 m

  8. Soft Bend Sync Radiation Mask 1 Mask 2 ±7.8 mm ±7.4 mm IP Mask Pass IP N = 3108 / BX k= 32 keV  (rad) The edge scattering from Mask 2 is a potential source of detector background, which is not estimated yet. R (cm)

  9. Quadrupole sync radiation and Collimation depth • Find collimation settings at SP2 and SP4. • Collimation depth – (nxsx, nysy) • Back track particles from IP to QF1.  Track particles from QF1 to IP, while generating SR. Find Nx and Ny that generate SR hitting the detector. x y  = n  IP x = 31 rad y = 14 rad

  10. Collimation Depth from Exit aperture Ny = 100 QF1 aperture limit Nx = 17 Ny Nx

  11. No. photons per e- - Exit aperture Ny Collimation depth: (nx,ny)=(12, 71) Nx

  12. Other apertures BeamCal 1.5 cm IP 1.2 cm Ny Nx Nx

  13. Collimation performance • Set the collimators at (nx,ny) = (12, 71) • Find # particles outside the collimation window. Jackson (PAC07) Drozhdin 1/x halo model Halo: uniform over 1.5x collimation depth. Nx=10 Collimation performance depends on the halo model.

  14. Beam Halo Jlab beam halo is small. • Simulation finds 3×10-5 halo. Burkhardt (PAC07)

  15. Possible SR studies • Assume a halo uniformly distributed over 1.5x collimation depth. • Assume 10-3 halo (2107/BX) • Find SR rate

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