A new doublet LSS for PS 2 Brennan

A new doublet LSS for PS 2 Brennan and Wolfgang PS 2 Meeting, 30 th July 2009 30 -July 09 Doublet LSS for PS 2 1

What did we have until now? • • LSS with 145 m length 4 x 90 deg FODO cells Central doublets for HSmaller bxy than arc 145 m MTEBKT Inj. K Inj. S Fast Inj 30 -July 09 MTEBK MS 2 Extraction H- Inj Doublet LSS for PS 2 MS 1 ES Ext. K Extraction 2

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? 30 -July 09 Doublet LSS for PS 2 3

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 30 -July 09 Doublet LSS for PS 2 4

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. 3 m wide • No intersection of beamlines near PS 2 (TTL 1 and new TT 10 will have to cross somewhere) 30 -July 09 Doublet LSS for PS 2 5

Optics – Foil inj. and extraction IS 30 -July 09 IK EK ES D 1 -D 4 EK MS EK Doublet LSS for PS 2 • Using last arc QF between DS and LSS for matching • Change over values: bx=54 m, by=15 m 6

Optics - Laser 15 m by in the centre 62 m bmax 30 -July 09 Can go to 9 m by in the centre Steady path for quadrupole tuning is not sure Doublet LSS for PS 2 7

LSS schematically Element Magnetic length [m] Strength [mrad] IS 0. 8 60 IK 0. 9 6. 8 EK 1 3. 1 1. 2 ES 3. 8 0. 8 EK 2 - - MS 7. 5 53. 1 EK 3 1. 7 0. 65 108 m 40 IS 75 IK EK 1 ES EK 2 MS EK 3 88 180 30 -July 09 Doublet LSS for PS 2 8

Beam lines 30 -July 09 Doublet LSS for PS 2 9

Optics perturbation by chicane Effect of the vertical focussing from the chicane 30 -July 09 Compensation by separate L/R powering of the quadrupoles (presently use all 10 quads) Doublet LSS for PS 2 10

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. 30 -July 09 Doublet LSS for PS 2 12