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SuperB Overview

SuperB Overview. P. Raimondi for the SuperB Team. SuperB IRC Meeting Frascati, Nov. 13 th 2007. Basic concepts.

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SuperB Overview

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  1. SuperB Overview P. Raimondi for the SuperB Team SuperB IRC Meeting Frascati, Nov. 13th 2007

  2. Basic concepts • B-Factories (PEP-II and KEKB) reach already very high luminosity (~1034 s-1 cm-2 ). To increase of ~ two orders of magnitude (ex. SuperKeKB) it is possible to extrapolate the requirements from the current machines: Parameters : • Higher currents • Smaller damping time (f(exp1/3)) • Shorter bunches • Crab collision • Higher Disruption • Higher power • SuperKeKB Proposal is based • on these concepts Increase of plug power ($$$$$..) and hard to operate (high current, short bunches) look for alternatives keeping constant the luminosity => new IP scheme: Small beams, ILC-like Large Piwinsky Angle and CRAB WAIST

  3. Crossing angle concepts All colliders do need short bunches to decrease the hourglass effect and the beams disruption Overlapping region With large crossing angle X and Z quantities are swapped: Very important!!! Sx Both cases have the same luminosity, (2) has longer bunch and smaller sx Sz 1) Standard short bunches Overlapping region Sz Sx 2) Crossing angle

  4. 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 • Vertical emittance goes down with the horizontal • 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

  5. 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) Crab waist realized with 2 sextupoles in phase with the IP in X and at p/2 in Y q 2Sz*q z 2Sz 2Sx Crab waist removes bb betratron coupling Introduced by the crossing angle

  6. Crab Waist Advantages • Geometric luminosity gain • Very low horizontal tune shift • Large Piwinski’s angle • F = tg(q)sz/sx • 2. Vertical beta comparable • with overlap area • bysx/q 3. Crabbed waist transformation • y = xy’/(2q) • Geometric luminosity gain • Lower vertical tune shift • Vertical tune shift decreases with oscillation amplitude • Suppression of vertical synchro-betatron resonances • Geometric luminosity gain • Suppression of X-Y betatron and synchro-betatron resonances

  7. Horizontal Plane Vertical Plane Collisions with uncompressed beams Crossing angle = 2*25mrad Relative Emittance growth per collision about 1.5*10-3 eyout/eyin=1.0015

  8. Beams are focused in the vertical plane 100 times more than in the present factories, thanks to: - small emittances - small beta functions - large crossing angle - Crab waist Tune shifts and longitudinal overlap greatly reduced KEKB Beams distributions at the IP SuperB Beams distributions at the IP

  9. Parameters Optimization: Transparency condition • Due to the large crossing angle, new conditions, instead of unbalanced currents, for having equal tune shifts with asymmetric energies are possible • LER and HER beams can have different emittances and b* and equal currents 

  10. e+ sees a shorter interaction region, (4/7 of the e- one) e+ has a smaller by*, natural to acheive in the FF e+ has larger emittance, 2.8nm better for the lower energy beam, less toushek, better tolerance for instabilities e- e+ LER sz HER sz

  11. Crab=0.8Geom_Crab Crab=0.9Geom_Crab HER LER Beam-beam blow up weak-strong simulations 1/e Density Contour lines L=1036 cm-2 s-1 D. Shatilov

  12. Beam lifetimes increased, injection rates reduced • Beam Beam simulations shows very good results, no blow up is seen for HER, 1-3% for LER, but some more optimization is possible: tunes, crabbing etc • L=10^36 is predicted • Upgrade parameters can be implemented in any order: - decrease the emittances first or - increase the bunch charge or - increase the number of bunches or - decrease the bunch length • Less RF Voltage is needed

  13. SuperB Parameters (Nov. 2007) (In red the CDR values)

  14. Possible site in the Tor Vergata University close to the Frascati Lab M. Sullivan

  15. SuperB Luminosity Tune Scan (crab=0.8/q, sz = 7 mm; 3x1010 particles) Lmax = 2.2x1036 cm-2 s-1

  16. Luminosity Tune Scan 1 IP 2 IPs Qy Qy Qx Qx Lmin = 3.95 x 1034 cm-2s-1 Lmax = 1.02 x 1036 cm-2s-1 Lmin = 3.37 x 1034 cm-2s-1 Lmax = 1.00 x 1036 cm-2s-1 M.Zobov, D.Shatilov

  17. The small emittance rings can be built by using all the PEP-II magnets, starting from the ILC DR design • The rings have circumference flexibility • The FF design complies all the requirements in term of high order aberrations correction, needs to be slightly modified for LER to take care of energy asymmetry • All PEP-II magnets are used, dimensions and fields are in range • RF requirements are met by the present PEP-II RF system

  18. Dipoles Summary Available • 130(112 in Arcs+18 in FF) “PEP-II HER” dipoles are used in SuperB HER • 18 “PEP-II HER” dipoles are used in FF for SuperB LER • 224 “PEP-II LER” dipoles are used in SuperB LER  need to build 30 new ones SuperB MagnetsShopping list

  19. Quadrupoles Summary Available * Spare 0.43 m long quadrupoles can be used (23)

  20. All and just the Pep RF system fits the SuperB needs

  21. Dafne Run with Crab Waist • Machine upgrade almost completed • Cold checkouts will start ‘round Nov.20 • Commissioning should last until Dec.20 • Physics run will begin in January until june-15 (goal Lint=1fb-1) • Luminosity goal is >5e32 (present record is 1.6e32) with crab sextupoles and >2e32 without

  22. Conclusions • SuperB studies are already proving useful to the accelerators and particle physics community • We have a preliminary “Conceptual Design Report”, based on the reuse of all the Pep hardware, that might fit in one of the existing facilities, or in a new (and avalaible) site near Frascati • We hope to gather in the enterprise as many labs and institutions as possible (see the CDR for the ones already involved)

  23. LHC Upgrade Possible fall back on the existing factories The crab waist seems to be beneficial also for the current factories Potential to simultaneously boost the performances of the existing machines and do SuperB R&D

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