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IR Design Status

IR Design Status. M. Sullivan For M. Boscolo, K. Bertsche, E. Paoloni, S. Bettoni, P. Raimondi, et al. Mini-MAC INFN Frascati, Italy Apr 23-24, 2009. Outline. Getting to the Present Design Improvements over July 2008 Layout Parameters SR summary Detector Solenoid More to do

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IR Design Status

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  1. IR Design Status M. Sullivan For M. Boscolo, K. Bertsche, E. Paoloni, S. Bettoni, P. Raimondi, et al. Mini-MAC INFN Frascati, Italy Apr 23-24, 2009

  2. Outline • Getting to the Present Design • Improvements over July 2008 • Layout • Parameters • SR summary • Detector Solenoid • More to do • Summary

  3. Latest design from last mini-MAC

  4. Some features of this design • First part of QD0 is PM just in front of the cryostat • Cold bore length is minimized (just under SC QD0) • QD0 design simplified (No QD0H – extra quad for the HEB) • QF1 design also simplified (side by side in the cryostat) • Warm bore under PM slices is smallest aperture and hence can intercept SR power (shields cold bore)

  5. Latest Design Improvements • After some iterating we have…. • Increased the crossing angle to +/- 30 mrads • Cryostat now has a complete warm bore • Both QD0 and QF1 are super-conducting • PM in front of QD0 for the LER only • LER has the lowest beta Y* • Soft upstream bend magnets • Further reduces SR power in IP area • Increased BSC to 30 sigmas in X and 140 sigmas in Y (10 sigma fully coupled) • Using the highest luminosity design parameters • Lowest beta* values and highest emittances Do NOT want to design out upgrades

  6. Nearly the Present Design

  7. Comparison to PEP-II Same scale as previous slide

  8. Inside the detector

  9. Some more details • Longer QD0 – increases the magnet aperture • QD0 strength was getting too high • Maintaining the gradient below 1.2 T/cm • Increased the space for the QF1 cold mass (from 4 mm to 6 mm) • Added a shared quad as part of QD0 • Starting design parameter for a warm bore design is that 5 mm is enough radial space between the cold mass and room temperature (recently got engineering confirmation that this is not crazy) • BSC in X is 30  uncoupled (all of the emittance in the X plane) and in Y we use 10  (fully coupled-50% of the total emittance) which is about 140 s E. Paoloni

  10. Parallel axis QD0 and QF1 • Presently the axes of the QD0 twin quads are parallel as are the axes of the twin quads of QF1 • The beams are bent through a small “s” bend by these quads because the beam goes through at a 30 mrad angle • Depends on where the quad axis is w.r.t. the beam trajectory • Have studied a case for tilted axis QD0 and QF1 magnets for SR backgrounds. About as good as this design. Magnet apertures can be smaller if we can align the magnets along the beam axis. • For now we will stay with the parallel axes design

  11. Close up of beam orbits in QD0 We have a double or “S” bend HER coming into the magnet QD0 axis The SR bending power from QD0 is 2x8793 W for a 2A beam The net bending angle is 1.85-4.25=-2.40 mrads HER outgoing

  12. Close up of QD0 beam orbits The net bending angle is 5.84-0.43=5.40 mrads LER coming into QD0 The SR bending power from QD0 is 2x1084 W for a 2A beam QD0 axis LER outgoing

  13. Permanent Magnets K. Bertsche designed the PM slices • The permanent magnets start the vertical plane focusing for the LER • With the larger crossing angle the beams are far enough apart at 0.35 m from the IP to have enough space to install a PM that can work on the LER • The PM quadrupole slices have an elliptical aperture to give us more vertical space • Dimensionally the slices are small • The chosen remnant field is high but not the highest (NeB is the material)

  14. Vertical View

  15. Beam parameters used Parameter HER LER Energy (GeV) 7 4 Current (A) 2.00 2.00 Beta X (mm) 20 35 Beta Y (mm) 0.27 0.16 Emittance X (nm-rad) 1.6 2.8 Emittance Y (pm-rad) 4.0 7.0 Sigma X (m) 5.7 9.9 Sigma Y (nm) 33 33 Crossing angle (mrad) +/- 30

  16. Magnet parameters • Quad G (kG/m) L(m) to IP (m) Bmax (T) • QD0L -522 0.40 0.58 1.23 (1.61) • QD0H -1192 0.40 0.58 2.80 • QF1L 399 0.30 1.60 1.92 • QF1H 726 0.30 1.60 3.48 • Dipole B (kG) L(m) from IP (m) • B0L -0.77 2.0 6.346 • B0H -1.35 2.0 6.346

  17. Vertical BSC • We discovered that the BSC envelope is higher than it is wide. This means the beam pipe gets too close to the cold mass in the beginning of QD0 • The inside diameter of QD0 is 47 mm • We ended up having to increase the size of the LER QD0. The inside diameter is now 62 mm.

  18. Too close 47 mm dia.

  19. 62 mm dia.

  20. SR backgrounds • No photons strike the physics window • Trace the beam out to 20 X and 45 Y • +/-4 cm for a 1 cm radius beam pipe • Unlike in PEP-II, we are sensitive to the transverse beam tail distributions • Photons presently strike 10 cm upstream and downstream of the IP

  21. SR from the upstream bends

  22. SR power (Watts) 854 425 732 73 2226 141 446 919

  23. Photons/beam bunch 194 6e8 6e6 4e5 7e7 1e8

  24. List of surfaces and how many photons strike each surface

  25. SR to do list • More thorough study of surfaces and photon rates • Backscatter and forward scatter calculations from nearby surfaces and from the septum • Photon rate for beam pipe penetration • Orbit deviation study • Beam tail distribution study • Working on acquiring some help for this work

  26. Detector solenoid compensation • We have taken a first look at detector solenoid effects on the beam orbit • The large crossing angle means the detector field strongly affects the beams • From a coupling point of view we probably need to cancel as much of the integral B.dl as we can • Most other IRs (KEKB and BEPCII) try to fully compensate the detector field

  27. BaBar detector field Bz along the Z axis The dotted lines are where QD0 and QF1 are located The asymmetric magnetic field complicates any compensation scheme

  28. Detector field only – Right side Incoming LER This study starts the beams at the IP. The no detector field orbit is a straight line along y=0. Outgoing HER

  29. Detector field only– Left side A little better because the total B.dl on the left side is lower. Outgoing LER Incoming HER

  30. Solenoid compensation from the P4 version of the IR design There is some B.dl left over

  31. 2L 2R 1L 1R

  32. Left side HER and LER orbits corrected with compensation solenoids and added VCOR Left side of IR LER Maximum orbit deviation is about 2 mm. HER

  33. Right side HER and LER orbits corrected with compensation solenoids and added VCOR Right side of IR LER Maximum orbit deviation is about 3 mm. HER

  34. Can we cancel the entire B.dl? • Version P5 • Increased the overlap between the two solenoids over QD0 and QF1 • Increased the length of solenoid over QF1 to include more detector field • Put in a small short solenoid in front of QD0 to cancel more of the field between the QD0 magnets closer to the IP (similar to KEKB and BEPCII) • Takes up most of the space out to the 300 mrad line for the physics window

  35. P5 layout 3L 2R 2L 3R 1L 1R 0L 0R

  36. P5 compensation

  37. Version P5 orbits – Left side Left side of IR Maximum orbit deviation is about 2 mm.

  38. P5 orbits – Right side Right side of IR Maximum orbit deviation is about 3 mm.

  39. P5A compensation (no small solenoids in front of QD0) There is some B.dl left over

  40. P5A Orbits – Left side

  41. P5A orbits – Right side The orbit deviation is actually better.

  42. Solenoid values for P4, P5 and P5A compensation schemes Values are in Tesla Sol. 3L 2L 1L 0L 0R 1R 2R 3R ----------------------------------------------------------------------------------------------------- P4 1.2 2.0 2.5 2.5 P5 0.45 1.0 1.3 2.5 2.5 1.58 1.6 1.6 P5A 0.45 1.2 1.7 0.0 0.0 1.8 1.8 1.8 More work to do here. Need to see what the lattice wants.

  43. Engineering to do list Being studied at INFN Pisa and at CERN • How do we build QD0? • How do we build QF1? • Transition space from warm bore to cold magnet wires • Magic flange locations (CESR, KEK and BEPCII have done it) • Bellows location to relieve stress on detector Be beam pipe • Cryostat supports • Vacuum supports • Where can we put pumping? • Vibration compensated magnet supports • …… First look at this from SLAC

  44. People • We have one cryo engineer looking at the small transistion space between the cold magnet and the warm bore. His preliminary report looks quite encouraging. Heat leak rates of 2-3 W/m2 which in his words is “reasonable”. • We will have another cryogenics engineer coming on board in July to study the overall cryostat construction including forces etc. • We have some time from a cryo designer

  45. Some Designer Drawings First crucial step will be getting a color scheme he and I agree on

  46. Summary • The present IR design has greatly improved since the last July machine advisory review • All the magnets inside the detector are now either PM or SC • The beam pipes inside the cryostats are now warm • We now have a 30 BSC in X and 140 BSC in Y (10 fully coupled) • Synchrotron radiation backgrounds look ok, but need more study • Radiative bhabha backgrounds should be close to minimal • Designing to the most aggressive machine parameters in order to NOT design them out

  47. Conclusions • Good progress has been made • Much more to do but the design is firming up • SR backgrounds need more study • Solenoid compensation is ready for lattice input • We are starting a first order engineering design of the cryostat

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