SuperB Accelerator Physics Activities: Beam Beam Interaction and Intrabeam Scattering

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SuperB Accelerator Physics Activities Beam Beam
Interaction and Intrabeam Scattering

• Gabriele Bassi
• for the University of Liverpool Accelerator Group
  and Cockcroft Institute
• SuperB QMUL Meeting
  London, July 11, 2008

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Outline

• SuperB project
• Luminosity and Beam-Beam Interaction
• Intrabeam Scattering
• Outlook and Future Work

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SuperB Project

• SuperB aims at the construction of a very high
  luminosity (1-4 x 1036 cm-2 s-1 ) asymmetric ee-
  Flavour Factory, with possible location at the
  campus of the University of Rome Tor Vergata,
  near the INFN Frascati National Laboratory.

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SuperB Accelerator Contributors

• M. E. Biagini, M. Boscolo, T. Demma, A. Drago, S.
  Guiducci, M. Preger, P. Raimondi, S. Tomassini,
  C. Vaccarezza, M. Zobov (INFN/LNF, Italy)?
• Y. Cai, A. Fisher, S. Heifets, A. Novokhatski,
  M.T. Pivi, J. Seeman, M. Sullivan, U. Wienands,
  W. Wittmer (SLAC, US)?
• T. Agoh, K. Ohmi, Y. Ohnishi (KEK, Japan)?
• I. Koop, S. Nikitin, E. Levichev, P. Piminov, D.
  Shatilov (BINP, Russia)
• Wolski (Liverpool University/Cockcroft Institute,
  UK)?
• M. Venturini (LBNL, US)?
• S. Bettoni (CERN, Switzerland)?
• A. Variola (LAL/Orsay, France)?
• E. Paoloni, G. Marchiori (Pisa University,
  Italy)?

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SuperB footprint on Tor Vergata site
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Super-B New Parameters
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Comparison of SuperB to SuperKEKB
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Basic concepts

• B-Factories (PEP-II and KEKB) reached very high
  luminosity (gt1034 s-1 cm-2 ), but to increase L
  of two orders of magnitude bordeline parameters
  are needed, such as
• Very high currents
• Smaller damping time Difficult and costly
• Shorter bunches operation
• Crab cavities for head-on collision
• Higher power
• SuperB exploits an alternative approach, with a
  new IP scheme
• Small beams (ILC-DR like)?
• Large Piwinski angle and crab waist
• Currents comparable to present Factories

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Beam-Beam Interaction (BBI)?

• BBI most important limitation to luminosity
  performance
• BBI is a complicated effect, it can be calculated
  only with computer simulations
• Simulations for SuperB carried out with
  Weak-Strong BBI code LIFETRACK
• Simulations for DA?NE carried out with 3D
  Strong-Strong BBI code BBSS
• LIFETRACK not self-consistent, BBSS very time
  consuming
• Improvements of existing codes/models is in our
  agenda

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Crab-waist Studies at DAFNE at INFN Frascati

• P. Raimondi et al DA?NE upgrade with improved
  interaction region to focus tighter the beams at
  IP and have a large crossing angle ? large
  Piwinski angle
• Features
• Smaller collision area
• Lower???y
• No parasitic crossings
• No synchro-betatron resonances due to the
  crossing angle
• Crab Waist sextupoles
• Results very encouraging so far with improved
  tunes shifts and higher luminosity with smaller
  currents.

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DA?NE tests showing Enhanced beam-beam Tune
shifts at lower Currents (Raimondi et
al)? (March 2008)?
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• SuperB beams are focused in the y-plane 100 times
  more than in the present factories, thanks to
• - small emittances
• - small beta functions
• larger crossing angle
• Tune shifts and longitudinal overlap are
  greatly reduced

y(?m)?
x(?m)?
z(mm)?
y(?m)?
x(?m)?
z(mm)?
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Beams distribution at IP
Without Crab-sextupoles
waist line is orthogonal to the axis of one bunch
With Crab-sextupoles
waist moves to the axis of other beam
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(M. Sullivan)?
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Intrabeam Scattering (IBS)?

• IBS multiple small-angle scattering events
• IBS leads to emittance growth
• Formalisms for IBS growth rates Piwinski,
  Bjorken-Mitingwa
• For calculation of SuperB IBS emittance growth
  Kubo-Mitingwa-Wolski formulae based on
  approximations of Bjorken-Mitingwa formalism
• Simulations of IBS for SuperB done by Wolski for
  old set of parameters (see CDR)?
• Simulations for the new set of parameters is on
  our agenda

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Outlook and Future work

• The initial SuperB design meets the goals
  requested by the experimenters
• Beam dynamics issues are receiving fresh look
• Liverpool Accelerator Group/Cockcroft Institute
  BBI, IBS...
• The next phase for the accelerator group is to
  form a team to complete the Technical Design
  Report