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Dafne Upgrade with large Piwinsky angle and crab waist

Dafne Upgrade with large Piwinsky angle and crab waist. P. Raimondi SLAC-Mac Oct.2006. Outline. Dafne luminosity History Goals for the Finuda run Goals for the Siddarta run Mid-Long term plans. Luminosity history. DA F NE DELIVERED L IN YEAR 2004-5 for KLOE. 109-111 bunches

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Dafne Upgrade with large Piwinsky angle and crab waist

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  1. Dafne Upgrade with large Piwinsky angle and crab waist P. Raimondi SLAC-Mac Oct.2006

  2. Outline • Dafne luminosity History • Goals for the Finuda run • Goals for the Siddarta run • Mid-Long term plans

  3. Luminosity history

  4. DAFNE DELIVERED LIN YEAR 2004-5 for KLOE 109-111 bunches I-peak =2.05 A I+peak = 1.39 A Lpeak = 1.53e32 cm-2s-1 Lday peak = 9.9 pb-1 Lmonth > 215 pb-1 L2004-5 > 2200 pb-1

  5. Finuda Run: Goal 1ft-1 by April 30, 2007 • - Start Oct-02 with cold check-outs • - 1 month commissioning • - 6 months data taking • Siddartha Run: Goal 1ft-1 by Dec 31, 2007 • - Install the new IR with cross-angle/crab-waist and Siddartha detector (2-3 months) • - start July-1st or Sept 1st • - 1 month commissioning • - 3 months data taking • Dafne Goal: 1033 By Dec 31, 2007 2006-7 goals LNF September 2006

  6. Started on Oct-02 • Reestablished collisions, stored >700mAmps e+/e- • Vacuum conditioning ‘til Oct-31 • Better coupling correction wrt Kloe (just 2 rotating quads instead of 4): 10% • Better e-ring impedance 20% (from shorter bunch and vertical emittance blowup) • Better feedbacks >10% (more current and more stable beams) • Reduced wiggler field (-10%) • Reduced run duration • 1.5*10^32 by the end of the run, 0.2ft-1/month duable Finuda Run

  7. New IR needed for Siddarta around mid-2007 • Very straightforward its design to overcome some of the present limitations and test the large crossing angle scheme • No more parasitic crossing • Very small vertical beta function • Large Piwinsky angle • Crab waist • Fast kickers installed Better injection efficiency: 50%=>100% • No background=> topping up • Higher currents => more luminosity (10%) • Wigglers pole modified to improve acceptance • Longer lifetimes • Less backgroung • Higher integrated luminosity (10%) • Ti Coating in the e+ wigglers chambers • Decreased e-cloud => Higher e+ current, more luminosity (20%) Siddarta Luminosity

  8. High luminosity requires: - short bunches - small vertical emittance - large horizontal size and emittance to mimimize beam-beam For a ring: • easy to achieve small horizontal emittance and horizontal size • Hard to make short bunches Crossing angle swaps X with Z, so the high luminosity requirements are naturally met Luminosity goes with 1/ex and is weakly dependent by sz

  9. x bY e- e+ 2Sx/q Vertical waist has to be a function of x: Z=0 for particles at –sx(- sx/2q at low current) Z= sx/q for particles at + sx(sx/2q at low current) Crabbed waist realized with a sextupole in phase with the IP in X and at p/2 in Y q 2Sz*q z 2Sz 2Sx Crabbed waist removes bb betratron coupling Introduced by the crossing angle

  10. Horizontal Plane Vertical Plane SuperB parameters Collisions with uncompressed beams Crossing angle = 2*25mrad Negligible Emittance growth

  11. Luminosity considerations Ineffectiveness of collisions with large crossing angle is illusive!!! Loss due to short collision zone (say l=σz/40) is fully compensated by denser target beam (due to much smaller vertical beam size!). Number of particles in collision zone: No dependence on crossing angle! Universal expression: valid for both - head-on and crossing angle collisions! I. Koop, Novosibirsk

  12. Tune shifts Raimondi-Shatilov-Zobov formulae: (Beam Dynamics Newsletter, 37, August 2005) Super-B: One dimensional case for βy >>σx/θ. For βy <σx/θ also, but with crabbed waist! I. Koop, Novosibirsk

  13. “Crabbed” waist optics Sextupole lens Anti-sextupole lens +g -g IP Δμx=π Δμy=π/2 Δμx=π Δμy=π/2 Appropriate transformations from first sextupole to IP and from IP to anti-sextupole: I. Koop, Novosibirsk

  14. Normalised Luminosity vs x and y tunes M. Zobov Vertical Size Blow Up (rms) vs x and y tunes With Crab Focus Without Crab Focus

  15. Beam size and tails vs Crab-waistSimulations with beam-beam code LIFETRAC Beam parameters for DAFNE2. An effective “crabbed” waist map at IP: Optimum is shifted from the “theoretical” value V=1 to V=0.8, since it scales like szq/sqrt((szq)2+sx2) D.N. Shatilov, Novosibirsk

  16. Synchrotron modulation of ξy(Qualitative picture) Head-on collision. Flat beams. Tune shift increases for halo particles. ξy(z-z0) Head-on collision. Round beams. ξy=const. Crossing angle collision.Tune shift decreases for halo particles. z-z0 Relative displacement from a bunch center Conclusion:one can expect improvement for lifetime of halo-particles! I. Koop, Novosibirsk

  17. M. Zobov Present achieved currents L=1.5e32 With the present achieved beam parameters (currents, emittances, bunchlenghts etc) a luminosity in excess of 1033 is predicted. With 2Amps/2Amps more than 2*1033 is possible Beam-Beam limit is way above the reachable currents

  18. SC Wigglers Wigglers off SC Wigglers Wigglers off Dafne Wigglers Dafne Wigglers Very weak luminosity dependence from damping time given the very small bb-blowup M. Zobov

  19. IR Layout • No splitters (on both sides) • Common beam pipe in QD0 • Separated beam pipes since QF1 • No dispersion in sextupoles due to splitters • Needs new extremely simplified vacuum pipe (round everywhere, apart the y-one) • Dipole fields need to be ajusted (Blong lower, Bshort higher)  use splitters power supplies • Doublets will be PM • All the other elements (quads, sexts etc) are in place, need just to be moved nearby

  20. New beam line IR layout IP QF1s QD0s M.Biagini

  21. Siddarta View of the modified IR1 region Similar modifications will be made in the IR2, without the low-beta insertion In addition in IR2 the two lines will be Vertically Separate

  22. Qf1s QD0 Permanent SmCo quads already ordered (about 380K$ for 6 quads) All other IR magnets and power supplies reused Most of the Vacuum Pipes and pumps reused New Vacuum pipes and pumps around 50K$

  23. Np=2.65*10^10 I=13mAmp*110bunches Emix=200nm Emiy=1nm Coupling= 0.5% sigx=200um betx=0.2m sigy=2.4um bety=6.0mm sigz=20mm crossing_angle=2*25mrad L(110bunches,1.43A)=10^33 y=y+0.8/q*x*y’ crabbed waist shift Dafne parameters for the Siddarta run

  24. Optical functions and dynamic apertures > 20 sigma_x > 12 sigma_y full coupled

  25. IR optics bx=1.4m by=18.0mm Old betas bx=0.2m by=6.0mm New betas M.Biagini

  26. If 10^33 is achieved (or some above 5*10^32) KLOE will start a new run with an upgraded detector. • the only significant (in money) modifications on Dafne could be: • - Transfer lines mods to allow trickle injection • - High Energy mods for NNbar experiment: • New Dipoles • Possibly X-Band Linac in the transfer lines to allow on energy injection • If the luminosity does not seems satisfactory, the only other possibility left (at the present) is the new machine DANAE, already at an advanced project state. Dafne 2008 and beyond

  27. Dafne Goals Conclusions • A new IR for Siddarta compatible with large-crossing angle option seems feasible • Same IR can fit in KLOE(1 or 2) • Predicted large luminosity boost based exclusively on pure “back of the envelope” geometric considerations, fully supported by extensive simulations • 10 times more luminosity for a given current leads to a 10 times better luminosity/background ratio. Additional gain comes from the increased (about a factor 1.2) beam stay clear in the IR • Possible to do top-of-the-line Accelerator Physics and R&D for future factories (e.g: SuperB) • Simply rematching the IP betas, it will be possible to run like with KLOE 2004-5, with even larger beam stay clear across the doublet: bx: 0.2m => 1.4m by: 6.0mm => 18mm

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