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E 166 “Polarized Positrons for Future Linear Colliders”

E 166 “Polarized Positrons for Future Linear Colliders”. John C. Sheppard E166 Co-spokesman SLAC: August 31, 2004. Introduction. Overview and purpose of E166 Experimental Setup Status & Milestones. Collaboration.

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E 166 “Polarized Positrons for Future Linear Colliders”

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  1. E166 “Polarized Positrons for Future Linear Colliders” John C. Sheppard E166 Co-spokesman SLAC: August 31, 2004

  2. Introduction • Overview and purpose of E166 • Experimental Setup • Status & Milestones

  3. Collaboration • About 45+2 members from 16+1 institutions from all three regions(Asia, Europe, the Americas, and Daresbury) • John Sheppard, Kirk McDonald (co-spokesmen)

  4. Overview of E166 • Demonstration experiment for production of polarized e+ • FFTB at SLAC with 50 GeV, 1010 e-/pulse , 30 Hz • 1 m long helical undulator produces circular polarized radiation 0-10 MeV • Conversion of photons to positrons in 0.5 rad Ti-target • Measurement of polarization of positrons by Compton transmission method Idea from Alexander Michailichenko

  5. Polarized positrons at linear colliders • The >150 GeV electron beam itself is used for the production of polarized positrons • Electron beam passes a 200m helical undulator (50% surplus) • After conversion, the positrons are captured and accelerated • They collide with a subsequent bunch train

  6. E-166 Experiment E-166 is a demonstration of undulator-based production of polarized positrons for linear colliders: - Photons are produced in the same energy range and polarization characteristics as for a linear collider; -The same target thickness and material are used as in the linear collider; -The polarization of the produced positrons is expected to be in the same range as in a linear collider. -The simulation tools are the same as those being used to design the polarized positron system for a linear collider. - However, the intensity per pulse is low by a factor of 2000.

  7. TESLA, NLC/USLCSG, and E-166 Positron Production ILC/ ILC

  8. E166 Equipment

  9. E166 Undulator Area

  10. Spectrometer Area

  11. Beam Intensities & Energies • 1010 electrons/bunch @ 50GeV into the undulator 5x106 phE 5 x 104 phE 4 x 109 photons @ < 10 MeV 4 x 109 photons 2 x 107 e+ 4 x 107 photons ~ 500 TeV 4 x 105 e+ 1 x 103 photons of total ~ 5 GeV (~ 5 MeV)

  12. The helical undulator • Rotating magnetic field • Wire winded helically • Inner diameter 0.89 mm • Magnetic field: 0.76 T • Pulsed current: 2300 A • Rate 30 Hz • 1010 e-/pulse incident

  13. Undulator radiation • Produced photons, cutoff and polarization Energy spectrum Polarization +1 5 MeV 5 MeV -1

  14. With Photons from Undulator Polarization / dN/dE Positron energy (MeV) 5 MeV Extraction Counts Pos. energy (MeV) Target and spectrometer • Target: Ti or W-Re, yield 0.5 % • Energy spectrometer: spread 20%

  15. CsI Calorimeter • „DESY Zeuthen and Humboldt University Berlin“ • Pack 3 x 3 crystals in a stack • CsI crystals: ~ 6 cm X 6 cm X 28 cm from DESY • ~1000 Re-converted photons -> Max 5 GeV • Readout by PIN diodes (large linear dynamic range) • 14 degrees aparture Magnet e+  W-Target

  16. Aerogel flux countersand Si-W calorimeter • Aerogel energy threshold: 4.3 MeV • Photon flux measurement • Si-W calorimeter • 4 x 4 Stack of 20 plates of W(1 rad. length thickness) • Up to 500 TeV signal • Total energy of undulator photons

  17. Status of Subcomponents

  18. E166 Milestones

  19. E166 Schedule • Now thru October 1, 2004: • Develop DAQ (T467) • Develop/build equipment • Install Equipment • PreBeam Equipment Check • October 1st thru November 1st : • Checkout, Backgrounds, Initial Data Run • January 1st thru February 1st, 2005 : • Checkout, Backgrounds, Initial Data Run

  20. E-166 Beamline Schematic 50 GeV, low emittance electron beam 2.4 mm period, K=0.17, helical undulator 10 MeV, polarized photons 0.5 r.l. converter target 51%-54% positron polarization Moffeit/Woods

  21. E-166 Beam Request • The SLAC FFTB: • Built to Demonstrate LC FFS: 60-70 nm rms spot • 28- 50 GeV Beam Energy • ge = 1.5x10-5/ 1.5x10-6 m-rad (x/y) • sz = 50-500 mm • Nb = 0.1-4x1010 e-/bunch • 2.5 kW Power Limit (1x1010 @ 30 Hz and 50 GeV) • 1 W Continuous Beam Loss Limit

  22. SLAC FFTB

  23. SLAC FFTB

  24. E166 FFTB Tunnel 1

  25. E166 FFTB Tunnel 2

  26. E166 FFTB Optics, RHI

  27. E166 PS: B406

  28. E166 DAQ: B407

  29. E166 CsI and Electronics,B407

  30. E166 CsI and Electronics,B407

  31. SLAC FFTB, IP1

  32. SLAC FFTB:B06G, PC7.5

  33. SLAC FFTB: Det. Tables

  34. SLAC FFTB g Table

  35. Cornell: Undulators

  36. DESY-HH: Analyzer Magnets

  37. E-166 Beam Measurements • Photon flux and polarization as a function of K. • Positron flux and polarization for K=0.17, 0.5 r.l. of Ti vs. energy. • Positron flux and polarization for 0.1 r.l. and 0.25 r.l. Ti and 0.1, 0.25, and 0.5 r.l. W targets. • Each measurement is expected to take about 20 minutes. • A relative polarization measurement of 10% is sufficient to validate the polarized positron production processes

  38. Conclusions • E166 is a demonstration of production ofpolarized positrons for future linear colliders • Uses the 50 GeV FFTB at SLAC • Approved by SLAC in June 2003 • Installation of total experiment in FFTB tunnel in August, September, October(?) 2004 • First data taking run in October 2004 • Second data taking run in January 2005

  39. The end …

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