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Sullivan, M. K.

Paper Title Page
MOYKI01 e+e- Factories 12
 
  • M. K. Sullivan
    SLAC, Menlo Park, California
 
  Funding: Work supported by USDOE contract DE-AC02-76SF00515

The achievements of the e+e- Factories have been impressive. The KEK B- Factory has achieved a peak luminosity of 1.7x1034 cm2/s and the PEP-II B-Factory has reached 1.2x1034 cm2/s while the Dafne Phi-Factory has obtained 1.5x1032 cm2/s. Early in the B-Factory running, CP violation in the B meson system was found to be consistent with the prediction of the Standard Model. Now all three factories are integrating as much luminosity as they can in order to look for rare decay channels that may have a rate that differs from the value predicted by the Standard Model and therefore hint at New Physics. I will give a status report on the most recent accomplishments of all three factories PEP-II, KEKB and Dafne and will show what the three facilities have for plans to further improve performance.

 
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MOZAKI03 PEP-II at 1.2·1034/cm2/s Luminosity 37
 
  • J. Seeman, Y. Cai, M. K. Sullivan, U. Wienands
    SLAC, Menlo Park, California
 
  Funding: Work supported by US DOE contract DE-AC02-76SF00515.

For the PEP-II Operation Staff: PEP-II is an asymmetric e+e- collider operating at the Upsilon 4S and has recently set several performance records. The luminosity has reached 1.2x1034/cm2/s and has delivered an integrated luminosity of 910/pb in one day. PEP-II operates in continuous injection mode for both beams boosting the integrated luminosity. The peak positron current has reached 3.0 A of positrons and 1.9 A of electrons in 1732 bunches. The total integrated luminosity since turn on in 1999 has reached over 410/fb. This paper reviews the present performance issues of PEP-II and also the planned increase of luminosity in the near future to over 2 x 1034/cm2/s.

 
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TUPAN034 Super-B Factory using Low Emittance Storage Rings and Large Crossing Angle 1460
 
  • J. Seeman, Y. Cai, M. K. Sullivan, U. Wienands
    SLAC, Menlo Park, California
  • M. E. Biagini, P. Raimondi
    INFN/LNF, Frascati (Roma)
 
  Funding: Work supported by US DOE contract DE-AC02-76SF00515.

Submitted for the High Luminosity Study Group for an Asymmetric Super-B-Factory: Parameters are being studied for a high luminosity e+e- collider operating at the Upsilon 4S that would deliver a luminosity of over 1036/cm2/s. This collider would use a novel combination of linear collider and storage ring techniques. In this scheme an electron beam and a positron beam at 4 GeV x 7 GeV are stored in low-emittance damping rings similar to those designed for a Linear Collider (LC). A LC style interaction region is included in the ring to produce sub-millimeter vertical beta functions at the collision point. A large crossing angle (±30 mrad) is used at the collision point to allow beam separation and reduce the hourglass effect. Beam currents of about 3 A x 2 A in 1700 bunches can produce a luminosity of 1036/cm2/s. Design parameters and beam dynamics effects are discussed.

 
TUPAN049 Low Emittance Lattices and Final Focus Design for the SuperB Project 1499
 
  • Y. Ohnishi
    KEK, Ibaraki
  • M. E. Biagini, P. Raimondi
    INFN/LNF, Frascati (Roma)
  • Y. Cai, J. Seeman, M. K. Sullivan, U. Wienands
    SLAC, Menlo Park, California
  • A. Wolski
    Liverpool University, Science Faculty, Liverpool
 
  For the SuperB project* very low emittances (horizontal < 1 nm) and small beta functions at the Interaction Points are required to achieve the design luminosity of 1036/cm2/s. Low emittance lattice have been designed, using the PEP-II magnets, for the two rings of 4 and 7 GeV, which will have the same emittances and damping times. A new Final Focus section has also been designed to get the strong focusing at the Interaction Point, at the same time providing local correction of the high chromaticity and exploiting the large crossing angle and crabbed waist concepts. Lattice features and chromaticity correction schemes will be discussed. Dynamic apertures, with damping wigglers similar to the ILC ones, will also be presented.

* P. Raimondi, "New Developments for SuperB Factories", Invited talk, this Conference

 
TUPAS066 Interaction Region Design for a Super-B Factory 1805
 
  • M. K. Sullivan, J. Seeman, U. Wienands
    SLAC, Menlo Park, California
  • M. E. Biagini, P. Raimondi
    INFN/LNF, Frascati (Roma)
 
  Funding: Work supported by US DOE contract DE-AC02-76SF00515

We present a preliminary design of an interaction region for a Super-B Factory with luminosity of 1x1036 cm2/s. The collision has a ± 17 mrad crossing angle and the first magnetic element starts 30 cm from the collision point. We show that synchrotron radiation backgrounds are controlled and are at least as good as the backgrounds calculated for the PEP-II accelerator. How the beams get into and out of a shared beam pipe is illustrated along with the control of relatively high synchrotron radiation power from the outgoing beams. The high luminosity makes radiative bhabha backgrounds significantly higher than that of the present B-Factories and this must be addresed in the initial design.

 
TUPAS068 A Transverse Beam Instability in the PEP-II HER Induced by Discharges in the Vacuum System 1811
 
  • U. Wienands, W. S. Colocho, S. DeBarger, F.-J. Decker, S. Ecklund, A. S. Fisher, J. D. Fox, A. Kulikov, A. Novokhatski, M. Stanek, M. K. Sullivan, W. Wittmer, D. Wright, G. Yocky
    SLAC, Menlo Park, California
 
  Funding: Work supported by US Dept. of Energy

During Run 5, PEP-II has been plagued by beam instabilities causing beam aborts due to radiation in the BaBar detector or due to fast beam loss triggering the dI/dt interlock. The latest of such instabilities occurred in the High Energy Ring (HER), severely curtailing the maximum beam current achievable during physics running. Techniques used in tracking down this instability included fast monitoring of background radiation, temperatures and vacuum pressure. In this way, the origin of the instability was localized and inspection of the vacuum system revealed several damaged bellows shields. Replacing these units significantly reduced the incident rate but did not eliminate it fully. After the end of the run, a number of damaged rf seals were found, possibly having caused the remaining incidents of instability. In this paper we will outline the steps taken to diagnose and remedy the issue and also compare the different signatures of vacuum-induced instabilities we have seen in both rings of PEP-II during the run.

 
THPAS057 Significant Lifetime and Background Improvements in PEP-II by Reducing the 3rd Order Chromaticity in LER with Orbit Bumps 3618
 
  • F.-J. Decker, Y. Nosochkov, M. K. Sullivan, G. Yocky
    SLAC, Menlo Park, California
 
  Funding: *Work supported by Department of Energy contract DE-AC03-76SF00515.

Orbit bumps in sextupoles are routinely used for tuning the luminosity in the PEP-II B-Factory. Anti-symmetric bumps in a sextupole pair generate dispersion, while symmetric bumps induce a tune shift and beta beat. By coming two of these symmetric bumps with opposite signs where the second pair is 90 degree away, the tune shift cancels and the beta beat doubles. In the low energy ring (LER) we have four sextupole pairs per arc, where pair 1 and 3 are at the same betatron phase and pair 2 and 4are 90 degree away. By making two symmetric bumps with opposite sign in pair 1 and 3 the tune shift and the beta beat outside this region cancel, BUT the LER lifetime improved by a factor of three, losses by a factor of five, and the beam-beam background in the drift chamber of the BaBar detector by 20%. Simulations showed that the phase change at the second sextupole pair introduced by the beta beat can completely cancel the third order chromaticity.

 
FRPMS075 Modeling of the Sparks in Q2-bellows of the PEP-II SLAC B-factory 4213
 
  • A. Novokhatski, J. Seeman, M. K. Sullivan
    SLAC, Menlo Park, California
 
  Funding: Work supported by USDOE contract DE-AC02-76SF00515

The PEP-II B-factory at SLAC has recently experienced unexpected aborts due to anomalously high radiation levels at the BaBar detector. Before the problem was finally traced we performed the wake field analysis of the Q-2 bellows, which is situated at a distance of 2.2 m from the interaction point. Analysis showed that electric field in a small gap between a ceramic tile and metal flange can be high enough to produce sparks or even breakdowns. Later the traces of sparks were found in this bellows.

 
FRPMS076 A New Q2-Bellows Absorber for the PEP-II SLAC B-Factory 4219
 
  • A. Novokhatski, S. DeBarger, S. Ecklund, N. Kurita, J. Seeman, M. K. Sullivan, S. P. Weathersby, U. Wienands
    SLAC, Menlo Park, California
 
  Funding: Work supported by US DOE contract DE-AC02-76SF00515

A new Q2-bellows absorber will damp only transverse wake fields and will not produce additional beam losses due to Cherenkov radiation. The design is based on the results of the HOM analysis. Geometry of the slots and absorbing tiles was optimized to get maximum absorbing effect.

 
FRPMS066 Commissioning the Fast Luminosity Dither for PEP-II 4165
 
  • A. S. Fisher, S. Ecklund, R. C. Field, S. M. Gierman, P. Grossberg, K. E. Krauter, E. S. Miller, M. Petree, N. Spencer, M. K. Sullivan, K. K. Underwood, U. Wienands
    SLAC, Menlo Park, California
  • K. G. Sonnad
    LBNL, Berkeley, California
 
  Funding: Supported by US DOE under contract DE-AC03-76SF00515.

To maximize luminosity, a feedback system adjusts the relative transverse (x,y) position and vertical angle (y') of the electron and positron beams at the interaction point (IP) of PEP-II. The original system sequentially moved ("dithered") the electrons in four steps per coordinate. Communication with DC corrector magnets and field penetration through copper vacuum chambers led to a full-cycle time of 10 s. Machine tuning can move the beams at the IP and so had to be slowed to wait for the feedback. A new system installed in 2006 simultaneously applies a small sinusoidal dither to all three coordinates at 73, 87 and 103 Hz. Air-core coils around stainless-steel chambers give rapid field penetration. A lock-in amplifier at each frequency detects the magnitude and phase of the luminosity's response. Then corrections for all coordinates are determined using Newton's method, based on convergence from prior steps, and are applied by the same DC correctors used previously but with only one adjustment per cycle for an expected ten-fold increase in speed. We report on the commissioning of this system and on its performance in maintaining peak luminosity and aiding machine tuning.