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S2E optics design and particles tracking for the ILC undulator based e+ source

S2E optics design and particles tracking for the ILC undulator based e+ source. Feng Zhou SLAC ILC e+ source meeting, Beijing, Jan. 31 – Feb. 2, 2007. Main parameters. Layout of the ILC e+ source. Target to capture system (125 MeV)

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S2E optics design and particles tracking for the ILC undulator based e+ source

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  1. S2E optics design and particles tracking for the ILC undulator based e+ source Feng Zhou SLAC ILC e+ source meeting, Beijing, Jan. 31 – Feb. 2, 2007

  2. Main parameters

  3. Layout of the ILC e+ source • Target to capture system (125 MeV) • Target hall: 125 MeV dogleg,125-400 MeV NC pre-acceleration, and 400 MeV dogleg • 5.03 km 400 MeV transport • SC boost linac to 5 GeV • Linac-to-Ring: spin rotations, energy compression, and beam collimation. • 5-GeV beam dump

  4. Transport in Target hall • OMD (6T-0.5T): to transform e+ with small spot size and large divergence at the target into large size and small divergence at the capture cavities. • N.C. RF capture cavities system embedded in a 0.5 T of solenoid to accelerate e+ beam to 125 MeV. • PCAP - 125 MeV e+ beam dogleg: to separate e+ from e- and photons using a dogleg with 2.5 m of horiz. offset (by Nosochkov). • PPA - NC pre-accelerator consisting of L-band structures embedded in a 0.5 T of solenoid to accelerate e+ from 125 MeV to 400 MeV. • PPATEL - a 400-MeV horiz. and vert. dogleg to deflect the beam by 5 m and 2 m in the horiz. and vert. planes, respectively (by Nosochkov).

  5. PPATEL PCAP PPA PPATEL X (m) Y (m) PCAP PPA Z (m)

  6. 400 MeV 5-km Transport • PTRANa – to follow e- main linac tunnel for 4 km. • PTRANb – to bring e+ from e- main linac tunnel to e+ booster linac tunnel. • PTRANc – 479 m of transport to connect with booster linac. PTRANc PTRANb X (m) Y (m) PTRANa Z (m)

  7. 5-GeV e+ booster linac • Accelerate e+ beam from 400 MeV to 5 GeV. • Have 3 sections: - 400 MeV to 1.083 GeV (4 non-standard ILC CM, each CM has 6 9-cell cavities and 6 quads) - 1.083 GeV to 2.626 GeV (6 ILC CM, each has 2 quads) - 2.626 GeV to 5 GeV (12 standard ILC CM, each has 1 quad )

  8. LTR – Linac to Ring • Spin rotations to preserve polarization in DR: - Bending magnets: from longitudinal to horizontal plane =n7.929 at 5 GeV; here n=7 to get reasonable R56. - Solenoid: from horizontal to vertical, parallel or anti-parallel to the magnetic field in the DR: = 26.23 T.m at 5 GeV. • Energy compression: R56 and RF section • Collimations: to reduce beam loss in the DR • Emittance measurement, and 3 PPS stoppers • Matching section

  9. Emitt. station collimation solenoid RF 7X7.929 collimation solenoid Emitt. station 7X7.929 RF section

  10. 5-GeV e+ beam dump • As a beam dump: for 0.1% and 10% of energy spread, the half edge beam sizes x/y are 3.9cm/8.3cm and 14.3cm/8.3cm, respectively, which meet the dump window specifications (see D. Walz, Snowmass, 2005). • As an energy spectrometer: 0.1% of resolution. 1st Bend of PLTR arc, its power off for dump Dump bend Monitor for energy spectrometer Dump window

  11. Overall e+ source optics

  12. Overall e+ source geometry X (m) LTR Y (m) PCAP, PPA, and PPATEL PBSTR PTRAN Z (m)

  13. Multi-particle Tracking from the Target to the DR injection line • Multi-particle tracking from the Target to the capture system (125 MeV) (by Y. Batygin). • Elegant code is used to track the e+ beam through the rest of the beamline including the PCAP, PPA, PPATEL, PTRAN, PBSTR, and LTR. • Energy compression is optimized to accommodate more e+ within the DR 6-D acceptance: m, and (25MeV)(3.46cm)

  14. ILC e+ source physical apertures

  15. Target Target 125 MeV 125 MeV y’ (rad)  Time (s) y (m) • Undulator parameter: K=1, =1cm. • Target: 0.4 r.l., immersed B0=6T. • OMD: B=B0/(1+g.z), g=0.6/cm, z=18.3cm. Y. Batygin, www.slac.stanford.edu/~batygin/

  16. ILC e+ loss distribution along the beamline

  17. 50 MeV 2X3.46cm   With LTR, but w/o collimation W/o LTR Time (s) Time (s) 50 MeV 2X3.46cm  With LTR and collimation Time (s)

  18. RMS values of magnet errors for tracking

  19. No error No error x (rad) y (rad) y (m) x (m) with errors but no correction with errors but no correction y (rad) x (rad) x (m) y (m) With errors and correction With errors and correction y (rad) x (rad) x (m) y (m)

  20. Comparisons of capture efficiency

  21. Summary and outlook • S2E optics for e+ source is developed. • S2E tracking w/o and w/ errors is performed: 49.8% of e+ from the target are captured within the DR 6-D acceptance after energy compression. • e+ loss into DR is ~1% after LTR collimation; additional betatron collimators are needed to collimate 0.8% of e+. • Field and alignment errors and orbit correction are analyzed. • Toward EDR: optics and physical aperture optimizations; reducing e+ loss in the DR; modeling activation of the 5-GeV collimations; tolerances definition; and tuning requirements. F. Zhou, Y. Batygin, Y. Nosochkov, J, C.Sheppard, and M. D. Woodley, “Start-to-end optics development and multi-particle tracking for the ILC undulator-based positron source”, SLAC-PUB-12239, Jan. 2007.

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