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A new doublet LSS for PS2. Brennan and Wolfgang PS2 Meeting, 30 th July 2009. What did we have until now?. LSS with 145 m length 4x90 deg FODO cells Central doublets for H - Smaller b xy than arc. 145 m. MTEBKT. Extraction. H - Inj. Extraction. Fast Inj. InjK. InjS. MTEBK. MS2.
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A new doublet LSS for PS2 Brennan and Wolfgang PS2 Meeting, 30th July 2009 Doublet LSS for PS2
What did we have until now? • LSS with 145 m length • 4x90 deg FODO cells • Central doublets for H- • Smaller bxy than arc 145 m MTEBKT Extraction H- Inj Extraction Fast Inj InjK InjS MTEBK MS2 MS1 ES ExtK Doublet LSS for PS2
Motivation for Doublet LSS • Avoid physical intersections of transfer lines • see pres. by Christoph last meeting • Gain in drift lengths to avoid coil window/yoke passage in doublet quads • Looked problematic for FODO/doublet LSS • Save in total length to increase arc length • Makes 3-fold geometry easier • Improve change-over between dispersion suppressor and LSS • smooth optics from arc to LSS, easier matching? Doublet LSS for PS2
Constraints • Minimum drift for H-: 24 m • mx between MTE extr. bumpers: k*180 • mx between ES and MS: 90 + k*180 • mx between MTE extr. kicker and MS: 90 + k*180 • 17 T/m maximum quadrupole gradient (K < 0.1) • bxy ‘reasonable’ - below ~60 m • Two injection optics versions: • Foil inj. with bxy ca. 25 m and axy ~0 at foil • Laser inj. with by as low as possible and axy ~0 at IR • Path from Laser inj. to extr. optics with LSS mx constant Doublet LSS for PS2
New doublet concept of LSS • 2 pairs of doublets arranged symmetrically around the LSS centre • Doublet spacing arranged to give similar bxy to arc • Generous quad lengths (2.4 m) with low gradients (maximum ~0.06 m-2) • Assume quads are ~1.3m wide • No intersection of beamlines near PS2 (TTL1 and new TT10 will have to cross somewhere) Doublet LSS for PS2
Optics – Foil inj. and extraction • Using last arc QF between DS and LSS for matching • Change over values: bx=54 m, by=15 m IS IK EK ES D1-D4 EK MS EK Doublet LSS for PS2
Optics - Laser 15m by in the centre 62m bmax • Can go to 9 m by in the centre • Steady path for quadrupole tuning is not sure Doublet LSS for PS2
LSS schematically 108 m 40 75 EK2 ES IS IK EK1 MS EK3 88 180 Doublet LSS for PS2
Beam lines Doublet LSS for PS2
Optics perturbation by chicane Effect of the vertical focussing from the chicane Compensation by separate L/R powering of the quadrupoles (presently use all 10 quads) Doublet LSS for PS2
Conclusion • New concept looks significantly better • Shorter and simpler LSS • Fewer quads, types and families • No complicated coil windows or intersections • Smoother optics • More relaxed quad gradients and smaller apertures • inj/extr element strengths/lengths comparable or better • Drawbacks? • Less phase advance and less flexibility? • MTE incorporation (anyway not done for FODO/doublet)? • Propose to use as new baseline • Will optimise further in Autumn, then release sequences etc. Doublet LSS for PS2