WOAD  —  Lepton Accelerators and Colliders   (18-May-05   10:40—12:25)

Chair: A. Hutton, Jefferson Lab, Newport News, Virginia

Paper Title Page
WOAD001 Super-B Factories 64
  • H. Koiso
    KEK, Ibaraki
  Energy-asymmetric electron-positron B factories, KEKB and PEP-II, have been operated at the luminosity frontiers and have delivered the integrated luminosities of a few hundreds of /fb to experiments. For further progress in particle physics, a luminosity of higher than 100/nb/s is strongly required, which means higher beam currents, smaller beta functions at the interaction point, larger beam-beam parameters, shorter bunch lengths, etc. This paper will review major upgrade plans of both machines toward SuperKEKB and Super PEP-II.  
WOAD002 Lepton Collider Operation with Constant Currents 149
  • U. Wienands
    SLAC, Menlo Park, California
  Funding: Work supported by US DOE under contract DE-AC03-76SF00515

Traditionally, electron-positron colliders have been operating in a top-off-and-coast fashion with a cycle time depending on the beam life time, typically on the order of an hour. Each top-off involves ramping detector systems in addition to the actual filling time. The loss in accumulated luminosity is typically 20-50%. During the last year, both B-Factories have commissioned a continuous-injection mode of operation in which beam is injected without ramping the detector, thus raising luminosity integration by constant operation at peak luminosity. Constant beam currents reduce thermal drift and trips caused by change in beam loading. To achieve this level of operation, special efforts were made to reduce the injection losses and also to implement special gating procedures in the detectors, minimizing dead time. Bunch-injection control decides which bunch to inject into next while maintaining small charge variation between bunches. Beam collimation can reduce injection noise but also cause an increase in background rates. A challenge can be determining beam lifetime, important to maintain tuning of the beams. The paper will discuss the special features of continuous injection in both KEKB and PEP-II.

WOAD003 JLab 12-GeV Upgrade
  • A. Lung, L. Harwood
    Jefferson Lab, Newport News, Virginia
  Jefferson Lab is preparing to upgrade its 6 GeV Continuous Electron Beam Accelerator Facility (CEBAF) to 12 GeV reach in energy. The energy doubling will significantly extend the scientific reach in the three existing experimental Halls A, B and C, and the upgrade will add the capability of a newly constructed hall, Hall D, to study the ‘confinement of quarks’. The energy upgrade will be achieved by the addition of ten high performance high gradient SRF cryomodules into existing space in the north and south recirculating linacs that will enhance the energy per pass to the level of 2 GeV. The SRF modules will be constructed at JLab with achieved gradients in excess of 20 MV/m and associated power RF and controls. The cryogenics will be upgraded by 50%, the transport magnets enhanced to deal with the increased beam energy, and a special radiator placed in the path of the electron beam to produce up to 9 GeV photons for Hall D physics. The present status of the 12 GeV Upgrade project will be described along with a hint of the science to be achieved.  
WOAD004 A High Luminosity Electron-Ion Collider To Study the Fundamental Structure of Matter
  • R. Milner
    MIT, Middleton, Massachusetts
  Physicists seeking to understand the fundamental structure of matter in terms of Quantum Chromodynamics have identified a high luminosity (~1033 nucleon cm-2 s-1) electron-ion collider (EIC) with a center-of-mass energy range of approximately 10 to 100 GeV as the most promising next-generation accelerator configuration. The talk will briefly summarize the scientific motivation for EIC and describe a number of accelerator design configurations under consideration. Important areas requiring R&D for EIC realization will be identified.  
WOAD005 BEPCII Interaction Region Design and Construction Status 478
  • Y. Wu, F.S. Chen, X.W. Dai, J.B. Pang, Q.L. Peng, Y. Yang, Z. Yin, C.H. Yu, J.F. Zhang
    IHEP Beijing, Beijing
  • M. Wang
    CAEP/IFP, Mainyang, Sichuan
  BEPC (Beijing Electron Positron Collider) is now upgrading to a double-ring collider with a new and compact interaction region. The multi-purpose superconducting magnets and conventional dual aperture quadrupole magnets are used as final focusing quadrupole in the interaction region .The two beams collide at the interaction point with a cross angle of ±11 mrad and further beams separation is enhanced with the help of a septum bending magnet which locates just beyond the vertically focusing quadrupole and acts on the outgoing beam lines only. This paper will describe the IR design and its construction status.